8 Geology Packets
Topics involving traditional geology (minerals, rocks, & plate tectonics), geologic hazards (volcanoes & floods), and environmental geology (mining, coastal erosion, & climate change).
Name: _______________________________
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Lab #1: Geologic Time Packet
Introduction:
Geologists have divided Earth’s history into a series of time intervals using a combination of
absolute and relative dating methods. These time intervals are not equal in length like the hours in
a day. Instead the time intervals are variable in length. This is because geologic time is divided
using significant events in the history of the Earth. During this laboratory, you will the basic
science behind the organization of the geologic time scale.
Driving Questions:
1. What is the geologic time scale and how is it organized?
2. How do geoscientists identify, describe, and interpret the geologic
history of an area?
Learning Objectives: Upon the successful completion of this laboratory, you should be able to:
•
•
•
Be able to determine relative ages of rocks and geologic processes, and use this information to
interpret & construct geological histories.
Be able to define what an index fossil is and explain their significance in the organization of the
geologic time scale.
Understand how numerical age dating works and be able to apply absolute ages to geologic
materials and events.
Part I: Geologic Time, Dating, & Histories
A. Geologic Time
If you could dig a hole deep into Earth’s crust, you would encounter the geologic record, layers of rock stacked
one atop the other like pages in a book. As each new layer of sediment or rock forms today, it covers the older
layers of the geologic record. Thus, rock layers form a sequence from oldest at the bottom to youngest at the top.
They also have different colors, textures, chemical compositions, and fossils (any evidence of ancient life)
depending on the environmental conditions under which they were formed. Geologists have studied sequences of
rock layers wherever they are exposed in mines, quarries, river beds, road cuts, wells, and mountain sides
throughout the world. They have also correlated the layers (traced them from one place to another) across
regions and continents. Thus, the geologic record of rock layers is essentially a stack of stone pages in a giant
natural book of Earth history! And like the pages in any old book, the rock layers have been folded, fractured
(cracked), torn (faulted), and even removed by geologic events.
Geologists tell time based on relative and absolute dating techniques. Relative age dating is the process of
determining when something formed or happened in relation to other events. For example, if you have a
younger brother and an older sister, then you could describe your relative age by saying you are younger than
your sister and older than your brother. Absolute age dating is the process of determining when something
formed or happened in exact units of time such as days, months, or years. Using the example of above, you
could describe your absolute age just by saying how old you are in years.
Geologists “read” and infer Earth history from rocky outcrops and geologic cross sections by observing rock
layers, recognizing geologic structures, and evaluating age relationships among the layers and structures. The
Geologic Time Scale is a chart of the named intervals of the geologic record and their ages in both
relative and absolute time. It has taken geoscientists from around the world more than a century to construct
the present form of the geologic time scale.
Example of a Geologic Stratigraphic
Column from the Grand Canyon
Just as authors organize books into sections, chapters, and
pages, geologists have subdivided the rock layers of the
geologic record into named eonothems (largest units),
erathems, systems, series, stages, and zones of rock on the
basis of fossils, minerals, and other historical features they
contained. These physical divisions of rock also represent
specific intervals of geologic time. An eonothem of rock
represents an eon of time, an erathem of rock represents
and era of time, a system of rock represents a period of
time, and so on in the table.
B. Relative Dating
A geologist’s initial challenge in the field
is to subdivide the local sequence of
sediments and bodies of rock into
mappable units that can be correlated from
one site to the next. Subdivision is based
on color, texture, rock type, or other
physical features of the rocks, and the
mappable units are called formations.
Formations can be subdivided into
members, or even individual strata.
Surfaces between any of these kinds of
units are contacts.
Geologists use six basic laws/principles
for determining relative age
relationships among bodies of rock
based on their physical relationships.
Principles of Relative Dating
An unconformity is a contact between two rock units in which the upper unit is usually much younger
than the lower unit. Unconformities are typically buried erosional surfaces that can represent a break
in the geologic record of hundreds of millions of years or more. There are three kinds of
unconformities: disconformities, nonconformities, and angular unconformities.
Angular Unconformity: A contact that separates a younger, gently dipping rock unit from older
underlying rocks that are tilted or deformed layered rock. Angular unconformities generally represent a
longer time hiatus than do disconformities because the underlying rock had usually been
metamorphosed, uplifted, and eroded before the upper rock unit was deposited.
Nonconformity: A contact that separates a younger sedimentary rock unit from an igneous intrusive rock
or metamorphic rock unit. A nonconformity suggests that a period of long-term uplift, weathering, and
erosion occurred to expose the older, deeper rock at the surface before it was finally buried by the
younger rocks above it. A nonconformity is the old erosional surface on the underlying rock.
Disconformities: Erosional contacts that are parallel to the bedding planes of the upper and lower rock
units. Since disconformities are hard to recognize in a layered sedimentary rock sequence, they are often
discovered when the fossils in the upper and lower rock units are studied. A gap in the fossil record
indicates a gap in the depositional record, and the length of time the disconformity represents can be
calculated. Disconformities are usually a result of erosion but can occasionally represent periods of
nondeposition.
Relative Dating Practice Exercises (In-Class):
C. Principle of Fossil Succession
The sequence of strata that makes up the geologic record is a graveyard filled with the fossils of millions of kinds of
organisms that are now extinct. Geologists know that they existed only because their fossilized remains or the traces of
their activities (like tracks and trails). Geologists have also determined that fossil organisms originate, co-exist, or
disappear from the geologic record in a definite sequential order recognized throughout the world, so any rock layer
containing a group of fossils can be identified and dated in relation to other layers based on its fossils. This is known as
the Principle of Fossil Succession.
The sequence of strata in which fossils of a particular organism are found is called a range zone, which represents a
chron of time. Organisms whose range zones have been used to represent named divisions of the geologic time scale are
called index fossils. An index fossil must be unique and easy to identify, have a relatively short history (limited
thickness of strata), and be found in a large number of areas.
The principle of faunal succession allows scientists to use the fossils to understand the relative age
of rocks and fossils.
Fossils occur for a distinct, limited interval of time. In the figure, that distinct age range for each fossil
species is indicated by the grey arrows underlying the picture of each fossil. The position of the lower
arrowhead indicates the first occurrence of the fossil and the upper arrowhead indicates its last
occurrence – when it went extinct. Using the overlapping age ranges of multiple fossils, it is possible to
determine the relative age of the fossil species (i.e., the relative interval of time during which that fossil
species occurred). For example, there is a specific interval of time, indicated by the red box, during
which both the blue ammonite and orange ammonite co-existed. If both the blue and orange ammonites
are found together, the rock must have been deposited during the time interval indicated by the red box,
which represents the time during which both fossil species co-existed. In this figure, the unknown
fossil, a red sponge, occurs with five other fossils in fossil assemblage B. Fossil assemblage B includes
the index fossils the orange ammonite and the blue ammonite, meaning that assemblage B must have
been deposited during the interval of time indicated by the red box. Because, the unknown fossil, the
red sponge, was found with the fossils in fossil assemblage B it also must have existed during the
interval of time indicated by the red box.
C. Fossil Correlation
The principle of fossil correlation states that the strata containing a group of fossils that are all the same age must
be of similar age to the fossils. Strata are layers of rock, and each single layer is known as a stratum. The principle
works because each species has a finite life span, and these eventually become extinct and after extinction do not
reappear. Fossil correlation relies on geologists knowing the ages of certain planets and animals.
Index fossils have specific characteristics that make them useful in fossil correlation. They must be
unique and easy to identify. Index fossils must be found in a large number of areas, but only in a
limited thickness of strata. To satisfy these criteria the organisms must have existed for only a short
time period, geologically, while also having lived in many different areas of Earth.
Practice Applying Fossil Correlation
Examine the outcrops below . Use the index fossils to correlate them and then
determine which layers are the oldest and youngest.
1.
Which layers are the same age? Draw a line correlating them.
2.
Which layers are the youngest?
3.
Which layer is the oldest?
D. Geologic Histories
A geologic history is the sequencing of geologic events to tell the history (“story”) of a location. The
geologic history identifies rock types, depositional environments, sea level changes, faults, folds,
fossils, types of unconformities present, as well as any other information that can be inferred from
the rocks.
1.
2.
3.
4.
5.
6.
7.
How to Construct a Geologic History:
Apply the principles of Relative Dating.
Identify any sedimentary structures.
Identify any geologic structures-Folds or Faults.
Identify the rock types and possible depositional environments.
Identify any unconformities.
Identify any indication of sea level change. (Sed rock type!)
Sequence (oldest to youngest) and succinctly summarize the
geologic history of the location.
Identify Primary Sedimentary Structures
Sedimentary structures, like ripple marks, mud cracks, and graded bedding can provide clues about the
depositional environment and about the orientation of the rock layers. Sedimentary features can indicate
which layer was deposited on the top or the bottom.
Here are some examples of primary structures:
A. Graded bedding: when a mass of different sized grains settle out through water to form a layer of
sediment, course grains predominate at the bottom of the layer, fine grains at the top.
B. Wave ripple marks: when waves disturb sediment on the floor of the ocean or a lake, ripples form. The
points of the ripples point upward.
C. Raindrop impressions: when rain drops plow into soft mud, craters form. The crater basins are convex
down; the crater rims point up.
D. The orientation of included fossils: when empty, disaggregated clam shells are disturbed by waves on
the ocean floor, most of the shells end up with the outer (convex) side of the shell pointing upward. The
branches of tree roots point downward.
E.Vesicles in lava flows: vesicles are concentrated near the upper surface of a lava flow.
Identify Unconformities
Angular Unconformity
3. Identify Sea Level Changes (Transgression vs Regression)
•Transgression = Flooding due to sea level rise.
Shale
Limestone
Sandstone
Conglomerate
•Regression = Exposure due to sea level fall.
Conglomerate
(Youngest)
(Oldest)
(Youngest)
Sandstone
Limestone
Shale
(Oldest)
Geologic History Practice Exercises:
Use the Rock Key that is in the lab tutorial slides and the clues in the diagram to help you construct
geologic histories for the following cross-sections. Remember to identify geologic structures, sed
structures, unconformities , and sea level changes if they are present.
1.
J
Age
Most Recent
(Youngest)
First to
Happen
(Oldest)
Letter/
Number
Event/Feature/Description
2.
J
Age
Most Recent
(Youngest)
First to
Happen
(Oldest)
Letter/
Number
Event/Feature/Description
E. Radiometric Dating
The universe is full of naturally occurring radioactive elements. Radioactive atoms are inherently
unstable; over time, radioactive “parent atoms” decay into stable “daughter atoms.” When molten
rock cools, forming what are called igneous rocks, radioactive atoms are trapped inside. Afterwards,
they decay at a predictable rate. By measuring the quantity of unstable atoms left in a rock and
comparing it to the quantity of stable daughter atoms in the rock, scientists can estimate the amount
of time that has passed since that rock formed.
Parent Atoms: The atoms originally in the sample
Daughter Atoms: The ‘new’ element that is the product of the parent element’s decay.
Half-life: The amount of time it takes for half of the parent atoms in a sample to decay.
Idealized % Parent/Daughter Assuming No Material is Lost
Steps to Solving Radiometric Decay Problems:
1. Start by determining the fraction of the Parent isotope
(Undecayed) that is remaining.
2. Complete the Radiometric Decay Chart or refer to the Decay Pair
Chart to determine the fraction of a half life or number of half
lives that have elapsed.
3. Multiply the length of the half-life of the radioactive isotope by
the # half-lives that have past to determine the age of the rock.
Radiometric Decay Practice Exercises:
Apply the steps you’ve learned to solve the following radiometric decay problems. Show your work!
paleontologist estimates that when a particular rock formed, it contained 36mg of the
1. Aradioactive
isotope potassium-40. The rock now contains 4.5mg of potassium-40. The
half-life of potassium-40 is 1.3 billion years. About how old is the rock?
The half life of Uranium-235 is ~713 million years. A rock originally contained 24mg of U-235.
2. The
rock now contains only 3mg of U-235. About how old is this rock?
3. Uranium-238 decays very slowly, with a half-life of 4.5 billion years.
What percentage of a sample of Uranium-238 would remain after 281,250,000 years passed?
Name: _______________________________
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Section: ______________________________
Lab 6: Applied Plate Tectonics Lab Packet
This is packet is due uploaded through Assignments
Introduction:
The earth’s surface is broken and moving about, making our world of mountains and planes a very
dynamic place. Plate tectonics describes the behavior of earth’s outer shell, with pieces (plates)
bumping and grinding and jostling each other about. During Lab #3 we will examine the processes
involved in plate tectonics and learn about how geoscientists quantify and track plate movement. The
concepts presented in the laboratory will be applied throughout the semester, as plate tectonics plays
an intricate role in volcanoes, earthquakes, rock & mineral formation, and climate change.
Driving Question: How do geoscientists quantify tectonic plate movement?
Learning Goals: Upon the successful completion of this laboratory, you should be able to:
▫Differentiate between ocean & continental crust, identify locations where oceanic crust is created or
destroyed/recycled.
▫ Describe how the distribution of volcanoes and earthquakes varies in relation to tectonic boundaries.
▫ Describe the relationship between age and the topography of the ocean floor relative to plate boundaries.
▫Define the Theory of Plate Tectonics, identify the different types of plate boundaries and each of their
characteristic features, and explain the tectonic cycle.
▫Calculate and explain how the rate of tectonic plate movement is determined through the interpretation of
paleomagnetic data at mid ocean ridges (sea-floor spreading rate) and through hot spot tracking.
I. Web Investigation of Earth Structure & Plate Tectonics
1. Use the information in the interactive website to answer the following questions about
Earth’s layered structure.
https://ees.as.uky.edu/sites/default/files/elearning/module06swf.swf
A. Click the “Earthquake” button. How many minutes did it take for the P-waves
to reach the opposite side of the Earth?
B. Why do geoscientists have to use seismic wave data to study the interior of the
Earth?
C. Compare and contrast oceanic and continental crust.
(Composition, age, thickness, & density)
Oceanic Crust
Similarities
Continental Crust
D. What is the Moho? How do we know where it is located?
E. Compare and contrast the lithosphere and the asthenosphere?
Lithosphere
Similarities
Asthenosphere
2. Use the information in the interactive website to answer the following questions about
the break-up of Pangaea.
https://wwnorton.com/common/mplay/6.11/?p=/college/geology/earth5/
vid/&f=geo-breakup-of-pangaea&ft=mp4&cdn=1&cc=1
A. The rocks contain evidence of several other supercontinents that pre-date Pangaea. Name
two and identify when they occurred?
B. What processes are responsible for splitting continents a part and then pulling them back
together?
C. In the break-up of Pangaea animation the widths of the color bands represent ___________,
while the color represents the __________ of the oceanic crust. This information allows
geoscientists to calculate the sea-floor spreading rate. (Rate = Distance/Time)
3.
Use the information in the interactive website to answer the following questions about
plate tectonic boundaries.
https://ees.as.uky.edu/sites/default/files/elearning/module04swf.swf
A. Click the “Maps” button. Then select the “Continents” base map. Now click the white box
under the “Boundaries” button. Then click the white box under the “Names” button. Take a
moment to observe the plate boundary locations. Now click the “Boundaries” button to learn
about the three main types of plate boundaries.
i. Based on your observations, write a definition for a plate boundary.
ii. Define the motions that occur at the three main types of boundaries.
Convergent:
Divergent:
Transform:
iii. Which boundary type is associated with deep sea trenches?
Oceanic ridges?
B. Now click the white box under the “Volcanoes” button.. Take a moment to observe the
distribution of volcanoes. How does this distribution compare to the location of plate
boundaries?
i. Now click the “Volcanoes” button. Which type of boundary is most often on or near a
volcano?
ii. Now click the white box under “Hotspots”. Compare their distribution to the plate
boundaries. Now click the “Hotspots” button to learn about them. What is a hotspot?
Why do most hotspots NOT occur on plate boundaries?
You can “uncheck” Hotspots now!
C. Now click the white box under the “Earthquakes” button. Take a moment to observe the
distribution of Earthquake epicenters. How does this distribution compare to the location of
plate boundaries?
D. Click the “DETAILS” button to learn about each of the following types of plate boundaries.
Then complete each block diagram by drawing arrows to show plate movement. Finally,
label the dominant features/processes that apply to each boundary. Dominate features
include: oceanic crust, continental crust, volcanic arc, volcanic island arc, earthquakes,
mountains, mid ocean ridge, trench, rift, subduction zone, accretionary wedge, and sea floor
spreading.
1. Ocean- Continent Subduction
2. Continent – Continent Collison
3. Ocean-Ocean Subduction
4. Continental Rift
5. Ocean-Ocean Divergent
6. Continental Transform
These diagrams will be
useful when you complete
the Google Earth portion of
this packet!
II. Mapping Plate Tectonic Boundaries
Earthquakes and volcanic eruptions show that the Earth is a dynamic plane with enough energy beneath
its surface to cause disasters for those who live on its surface. For thousands of years humans wondered
about the causes of these events, until the 1960s and 1970s when geologists developed the theory of
plate tectonics—a unifying theory that answered geologic questions that had puzzled us for many years.
Plate tectonics explains the outer layer of the Earth as a group of separate plate that move with respect
to each other and change the Earth’s surface as they move. At first it was difficult to accept the concept
that Earth’s oceans, continents, and mountains are only temporary features that move and change over
time, as the changes were slow they could not be detected. Yet according to the plate tectonics theory,
planet-wide processes break continents apart, open and close oceans, and build and shrink great
mountain chains. Earthquakes and volcanoes are simply results of energy released as these processes
occur, so it makes sense that plate boundaries were originally discovered by plotting the location of
earthquake epicenters and volcanoes.
FIGURE 1. Dominant tectonic plates and plate boundaries. The location of plate boundaries correspond
to belts of tectonic activity—volcanoes, earthquakes, and mountain building.
No one ridicules plate tectonics now because evidence proved these processes are happening today, and
geologists showed that these processes have been operating for billions of years. In the following
exercises, you will have the opportunity to analyze some of evidence/scientific data used to support the
theory of plate tectonics.
Part III: Investigating Plate Tectonics with Google Earth (GE)
Now you will explore the evidence that scientists used to develop the theory of plate tectonics. Google
earth is a virtual globe application that allows you to explore, create, and analyze geographic information.
If you do not have Google Earth installed on your computer, follow the instructions below:
1. Navigate to http://earth.google.com
2. Click “Download Google Earth” (free version)
3. Read and agree to the software application terms.
4. Click the “RUN” icon. (Congratulations, GE is now installed on your computer)..
f you have never used Google Earth before, play around a little with the program. Be sure to check out
“Navigation” and “Drawing and Measuring” beginner tutorials at http://www.google.com/earth/learn/
5. Close the Google Earth application.
Download the Plate Tectonics Tour. kmz file to your computer:
1. Sign into the GEOL 101 Laboratory Sakai site.
2. Click the Lab #6: Plate Tectonic Tab and locate the Plate Tectonic Tour KMZ file and download it and
save it to your desktop. Remember where you save it!
Open GE and complete the following:
1. To get rid of clutter, we need to turn off all irrelevant layers… In the Layers Sidebar (bottom left),
deselect the “primary database” box so that there are no labels or boundaries displayed on the virtual
globe.
2. To make terrain easier to see, we are going to increase our vertical exaggerate (makes the mountains
taller and the valleys deeper). (PC: Main menu > Tools > Options or Mac: Google Earth >
Preferences), in the Terrain Quality section (half way down the window), enter a “3” in the “Elevation
Exaggeration” blank. Push OK.
3. Open the “PlateTectonicsTour.kmz” file that you downloaded from Sakai. In the “Places” sidebar (on
the left) you should see the “PlateTectonicsTour.kmz.” Expand it by clicking on the small triangle to the
left. Double click on the first item “1AB Mid Atlantic Ocean Ridge.”
Evidence for Plate Tectonics
1.
Ocean floor mapping (Bathymetry)
In the 1950s, data gathered by oceanographic surveys led to the discovery that a great mountain range
on the ocean floor virtually encircled the Earth. Called the global mid-ocean ridge, this immense
submarine mountain chain — more than 50,000 kilometers (km) long and, in places, more than 800 km
across — zig-zags between the continents, winding its way around the globe like the seam on a
baseball. Rising an average of about 4,500 meters above the sea floor, the mid-ocean ridge
overshadows all the mountains in the United States except for Mount McKinley in Alaska (6,194 m).
Though hidden beneath the ocean surface, the global mid-ocean ridge system is the most prominent
topographic feature on the surface of our planet.
a. In GE, examine the bathymetry of the Atlantic Ocean. The bottom of the GE window gives the
latitude, longitude, and elevation of the location of your curser. Find the Mid Atlantic Ocean ridge and
describe its shape… Is it closer to any one continent or does it lie in the middle in the Atlantic Ocean?
b. How does the shape of the Mid-Atlantic Ridge compare to the coasts of the continents surrounding the
Atlantic Ocean?
c. In the Places sidebar, double click the next item in the PlateTectonicsTour, “1C Mid Atlantic Ocean
Ridge Fracture”. Notice the numerous fractures running perpendicular to the Mid Atlantic ridge. Follow
the fracture to the west to where it intersects the coast of South America and then follow the fracture to
the east where it intersects with the coast of Africa. How does the location of these two intersections
support the conclusion that South America and Africa once fit together (look at the shape of the coasts)?
2. Concentration of Earthquakes
During the 20th century, improvements in seismic instrumentation and greater use of earthquakerecording instruments (seismographs) worldwide enabled scientists to learn that earthquakes tend to be
concentrated in certain areas.
a. In the PLACES sidebar, click on the little box to the left of “2 AB Earthquakes” to view all Earthquakes
recorded in 2010 by the United State Geological Survey. Note that to see all the earthquakes, you must
zoom in (ctrl + shift + up arrow). Are there many earthquakes near mid ocean ridges? Are they deep or
shallow (look at the symbol color).
b. Do more earthquakes occur on the edge or in the middle of the Atlantic Ocean? Do more
earthquakes occur on the edge or in the middle of the Pacific Ocean?
c. Click on next item in the PlateTectonicsTour, “2C Japanese Earthquakes”. What major
bathymetric feature is present near the string of earthquakes? You can view the area obliquely by
holding “Shift + down arrow” to get a better 3D perspective. What is the approximate elevation of
the ocean floor at “2C Japanese Earthquakes”? Remember, the bottom of the GE window gives
the elevation of your curser.
3. Age of the Ocean Floor
Using a variety of geochronological methods, scientists have been able to date the ocean floor. Unlike the
continental crust which is ~3.8 billion years old in some places, the ocean crust is relatively young with
rocks no older than ~200 million years.
Questions:
a.
Deselect the “2C Japanese Earthquakes” layer and the “2AB Earthquakes” layer. Then
select the “3 Ocean Crust Age.” Displayed is the color coded age of the ocean floor.
What is the relationship between ocean crust age and mid ocean ridges?
b. What is the relationship between the ocean crust age at ocean trenches (like the one off the
coast of Japan?) and at mid ocean ridges?
c. What does this imply about the movement of oceanic crust? In other words, how does this
support the theory that oceanic crust is moving away from mid ocean ridges and towards
ocean trenches?
d. Calculate the rate at which the Mid Atlantic ridge is spreading apart. Double click on “1C
Mid Atlantic Ocean Ridge Fracture” in the Places sidebar. Use the Ruler Tool to measure the
distance from South America to Africa along the fracture path specified by the yellow
thumbtack. *Hint: select the “Path” tab which allows you to measure curved lines. Report
your answer in cm/yr.
e. Are Australia and Antarctica moving away from each other faster or slower than South
America and Africa? What is the difference in rate between the two in cm/yr?
Questions:
In the Layers Sidebar, deselect “3 Ocean Crust Age” and select “Plate Boundaries.” This
layer shows the Earth’s tectonic plate boundaries and names. Fly to each of the locations
listed below by entering the latitude and longitude coordinates listed. Determine which
type of plate boundary is located at each location. Be specific—if convergent identify the
types of crust involved. Then identify several of the characteristic features present at the
boundary (earthquakes, volcanic arc, volcanic island arc, trench, ridge, etc).
b. Did you find volcanoes present at the transform boundaries you identified?
Why or why not?
c. Visit the following location: 10° 44’ 51 S and 32° 22’ 49 E. Then answer the
following:
1. What are the tectonic plates involved?
2. Describe the plate movement?
3. Identify which tectonic process is involved?
4. Which type of plate boundary do you think this will develop into over time? WHY?
5. Active vs Passive Continental Margins
Earthquakes and volcanic eruptions are common on the west coast of North America, but
there are no active volcanoes on the east coast and large magnitude earthquakes are rare.
Geologists refer to the west coast as a (tectonically) active continental margin and the east
coast a passive continental margin. These differences can be found on several continents.
Most passive continental margins have broad continental shelves, whereas active continental
margins typically have narrow continental shelves. In addition, active continental margins
are near plate boundaries whereas passive continental margins are further away from an
active plate boundary.
Questions:
A. Compare the west coast of South America with the west coast of Africa.
i.
Which has a broad continental shelf?
A narrow continental shelf?
ii.
Which is near a trench?
iii.
Which coast would you expect to have the most earthquakes? WHY?
iv. Based on your answers above, is the west coast of South America an active or passive
continental margin?
b.
Visit 30 43′ 02”N, 77 03′ 53”W Based on the features that you see, is this location
an active or passive continental margin? WHY? (Explain what you see!)
C. Based on what you now know about plate tectonics, explain why some continental
margins are active and others are passive. Do you think that continental margins change
through time? If so, how?
IV. Evidence for Seafloor Spreading
If you drop a pen, it falls to the floor. The pen is under the influence of Earth’s gravity—an invisible force field that
pulls everything and everyone towards the center of our planet. But Earth has another force field that is not so
obvious, its magnetic field. It is as though a giant bar magnet resides inside the Earth, giving our planet both a
magnetic north pole and a magnetic south pole. Invisible lines of magnetic force field arc out through space from
the south to form a magnetic pole, travel around the outside of the Earth at its equator, then arc back into the north
magnetic pole. You can use the tiny magnetic needle of a compass to detect Earth’s magnetic field. Magnetic
compass needles are not attracted to the geographic North Pole. Instead, they are attracted to the magnetic north
pole, which is located in the Artic Islands of Northern Canada, about 700km (450 miles) from the geographic North
Pole.
In the 1950s geologists learned that tiny crystals of ironrich minerals, such as magnetite (Fe3O4), acquire and
retain the directional signature of Earth’s magnetic field
when they form. This happen when volcanic lava cools
and crystalizes below the Curie Point (~580°C). This
ancient magnetism is called paleomagnetism.
Figure 2. Earth’s magnetic field is defined by magnetic
lines of force shown by arrows.
When geologists first started detecting paleomagnetism in
layers of cooled lava (volcanic rock) stacked one atop the
other, they discovered that Earth’s magnetic field has not
always been the same. It has undergone periodic
reversals. During times of normal polarity the north-
Seeking compass needle (and tiny iron-bearing mineral crystals in volcanic rock) points in the direction of Earth’s
present magnetic north pole. But during times of reversed polarity, the north-seeking end of the compass needle
points in the opposite direction (geographic south).
Magnetic anomalies are deviations from the average strength of the magnetic field
in a given area. Areas of higher than normal strength are positive anomalies and
areas of less than average strength are negative anomalies. In the late 1950’s the US
Coast and Geodetic Survey scanned the ocean for marine magnetic anomalies and
discovered that the rocks of the sea floor contained alternating striped patterns of
high and low magnetic anomalies, called paleomagnetic stripes.
They also
discovered that the pattern of paleomagnetic stripes was symmetrical on opposite
sides of mid-ocean ridges. In 1963, a group of scientists discovered that the
symmetrical pattern of the paleomagnetic stripes on the seafloor rocks was the result
of two processes: the formation of seafloor (lava cooling) and the reversals of
Earth’s magnetic field. They proposed that as volcanoes erupted along a mid-ocean
ridge, the lava cooled below the Curie Point and recorded the reversals of Earth’s
paleomagnetic field. Rocks formed during times of normal polarity now have
magnetic signatures that add to the modern field strength and create a positive
anomaly, while rocks formed during times of reversed polarity have magnetic
signatures that oppose the modern field and create a negative anomaly. The
symmetrical pattern of paleomagnetic stripes developed as new crust was formed
and magnetized and older crust moved down and spread away from both sides of the
ridge under the influence of gravity in a process called seafloor spreading.
Figure 3. Radiometric dating of lava flows shows magnetic reversals for only the past 4Ma.
Major intervals of positive or negative polarity are called chrons and are named after scientists who contributed to
the understanding of the magnetic field. Short duration reversals were called subchrons.
Figure 4. Magnetic anomaly stripes in the Atlantic and Pacific.
(a)
(b)
Activity
A. Interpreting Ocean Ridge Magnetic Stripes
In Figure 4a, compare the orientation of the magnetic anomaly stripes for the Mid-Atlantic
Ridge with the orientation of the ridge crest (dashed line). In Figure 4b, do the same for the
Juan de Fuca Ridge and its anomalies.
1. Are the individual anomalies orientated randomly? Are they parallel to the ridge
crests? Oblique to the ridge crests? (1pt)
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
2. Explain how the process of seafloor spreading can produce these orientations and
relationships. (1pt)
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
3. Some magnetic stripes are wider than others. Knowing what you do about the
seafloor spreading and magnetic reversals, suggest an explanation. (1pt)
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
Activity
B. Comparing Seafloor Spreading Rates in Different Basins
Magnetic reversals are found worldwide, so magnetic stripe should be the same width in
every ocean if the rate of seafloor spreading is the same at all ridges. If a particular
anomaly is wider in one ocean than another, however, it must result from faster spreading.
The figure on the right shows simplified magnetic stripes from the South Atlantic and
Pacific oceans, the ages of the rocks and the distance from the spreading center (ridge
crest). For simplicity, only the most recent 80 million (Ma) years of data are shown for the
two ocean basins.
Figure 5. Map view of magnetic anomaly stripes in two ocean basins.
Black = normal polarity.
1. Measure the distance from the spreading center to the farthest magnetic anomaly stripe in each
ocean and determine the age of that anomaly. (4pts)
South Atlantic Ridge: ______________________km
Age: ____________________
East Pacific Rise: ______________________km
Age: ____________________
2. Calculate the TOTAL spreading rate (in cm/yr and in km/m.y.) for each ridge.
[Remember these data are for only one side of the ocean ridge, so , to calculate TOTAL spreading
rate, you will need to double the spreading rate.] (4pts)
South Atlantic Ridge: __________km/Ma
East Pacific Rise:
_________cm/yr
__________km/Ma
_________cm/yr
*Hint: There are 1,000,000 millimeters in a kilometer!
3. Why are the anomalies in the East Pacific wider than those in the South Atlantic? (2pts)
__________________________________________________________________________
__________________________________________________________________________
V. Plate Motion at a Continental Transform Fault
Continental transform faults can be found in New Zealand (Apline Fault), Turkey (Great Anatolian
Fault), Haiti (Enriquillo-Plantain Garden Fault), and the US (San Andreas Fault). The San Andreas
Fault system of California is an active transform boundary that has caused major damage and the loss of
life over the past 100 years. It is comprised of a network of several faults. It extends for more than
1000km, connecting segments of the Juan de Fuca Ridge and Cascade Trench at its northern end to an
unnamed ridge segment in the Gulf of California to the south.
Activity
A. Tracking the Amount and Rate of Motion Along the San Andreas Fault
The more we know about the history of a continental transform fault close to heavily
populated regions, the better we can prepare for its next pulse of activity. Geologists try to
find out hos long a continental transform fault has been active, how much it offsets the
plates it separates, and how fast it has moved in the past.
Geologists estimate that the San Andreas Fault system has been active for about 20 million
years. This exercise shows how geologists use geologic markers cut by faults to measure
the amount and rate of motion along a transform fault.
Figure 6. (A) Simplified geologic setting of San Andreas Fault system. (B) Amount of fault movement
indicated by offset bodies of identical rock. (Color diagram is available via the PDF on Sakai.
Field geologists have mapped an active continental transform fault (labeled below) for several
hundred kilometers. A 50-million year old (50Ma) body of granite and a 30Ma vertical layer of
marble have been offset by the fault as shown.
Figure 7. Geologic markers displaced by a continental transform fault.
Transform fault
1.
Draw arrows to the direction in which the pate on the northeast side of the fault has moved
relative to the plate on the southwest side. (1pt)
2.
Measure the amount of offset to the 50-Ma granite body. _______________ km (1pt)
3. The geologists have proved that faulting began almost immediately after the granite formed
and continues today. If the fault blocks moved at a constant rate for the past 50 million years,
calculate the rate of the offset. (plate movement rate) (2pts)
_________________km/million years
____________________mm/year
4. Assume the fault blocks moved at a constant rate for the past 30 million years and calculate
the offset rate. (plate movement rate) (2pts)
_________________km/million years
____________________mm/year
5. Based on your calculations, has the rate of the offset (plate movement) been constant for
the past 50 million years? Why or why not? (1pt)
VI. Analyzing Hot Spots to Track Plate Motion
Mantle plumes are areas of hot, upwelling mantle. A hot spot develops above the plume. Magma generated by the
hot spot rises through the rigid plates of the lithosphere and produces active volcanoes at the Earth’s surface. As
oceanic volcanoes move away from the hot spot, they cool and subside, producing older islands, atolls, and
seamounts. As continental volcanoes move away from the hot spot, they cool, subside, and become dormant and
eventually extinct.
Hot spots are places within the mantle where rocks melt to generate magma. The presence of a hot spot is inferred
by anomalous volcanism (i.e. not at a plate boundary), such as the Hawaiian volcanoes within the Pacific Plate. The
Hawaiian hot spot has been active at least 70 million years, producing a volcanic chain that extends 3,750 miles
(6,000 km) across the northwest Pacific Ocean. Hot spots also develop beneath continents. The Yellowstone hot
spot has been active at least 15 million years, producing a chain of calderas and volcanic features along the Snake
River Plain that extends 400 miles (650 km) westward from northwest Wyoming to the Idaho-Oregon border.
Activity
A. Tracking the Movement of the Pacific Plate via the Hawaiian Hot Spot
The Hawaiian Islands, located in the Pacific Ocean far from the nearest oceanic ridge, are an
excellent example of hot spot volcanic islands (see figure below). Volcanoes on Kauai, Oahu, and
Maui have erupted for millions of years, but the island of Hawaii hosts five huge volcanoes, one of
which (Kilauea) has been active for the past 31 years. In addition a new volcano, Loihi, is growing
on the Pacific Ocean floor just southeast of Kilauea. As the Pacific Plate moves, Kilauea will
become extinct and Loihi will be the primary active volcano.
1. Where is the Hawaiian hot-spot plume located today relative to the Hawaiian Islands?
Explain your reasoning. (1pt)
__________________________________________________________________________
__________________________________________________________________________
2. Use a ruler to draw a line connecting each volcano center (tip of arrow). Connect Maui to
Molokai, Molokai to Oahu, and Oahu to Kauai. (1pt)
3. Measure distance between the volcanic centers of the Hawaiian Islands using a ruler and
the map scale. Then calculate the rate of plate motion (distance between volcanoes divided by
the time interval between eruption ages. Record your answers in the table on the next page.
Express the rates in millimeters per year. (8pts)
Figure 8. Hawaiian Hot Spot Track.
Distance between
volcanic centers (km)
Number of years of
plate motion
(Ma)
Rate of plate motion
(mm/yr)
Hawaii to Maui
Maui to Molokai
Molokai to Oahu
Oahu to Kauai
*Hint: There are 1,000,000 millimeters in a kilometer!
GEOL 101L: Climate Change
Paleoclimatology: Reconstructing past climates
We talked about climate and how geoscientist use many
different proxies as a means of estimating paleotemperature,
or temperatures in the past.
This laboratory will give you the opportunity to try four (4)
different proxies that are common in the study of
paleoclimate. These proxies include stable isotope records
from ice cores and marine sediment cores, assemblage data
from trees (pollen) and marine fossils.
You will then use directly measured instrument data and
observation data to investigate Recent climate change. This
includes graphs of atmospheric CO2(g) and the observable
retreat of glacial ice in North America.
Part 1: Pleistocene Climate Reconstructions
On the follow page is displayed ice core data, obtained from
the Vostok ice core in Antarctica and a marine sediment core,
which was recovered from the middle of the North Atlantic
Ocean. Plot the isotope data from the ice and sediment cores.
On your graphs, label the areas of the graph that represent
hot and cold temperatures using our discussion of stable
isotope principles. A record is a pollen record from a lake in
Japan. By observing warm- and cold-weather species, you
can make a temperature record for the lake. Unlike your other
graphs, pollen data won’t show exact values, just hot, cold, or
intermediate temperatures.
1
Plot the isotope data from the ice and sediment cores.
On your graphs, label the areas of the graph that
represent hot and cold temperatures using our discussion
of stable isotope principles.
2
3
Plot the isotope data from the ice and sediment cores. On
your graph, label the areas of the graph that represent hot
and cold temperatures. Make another graph for the pollen
data.
4
1. What stands out about your temperature graphs? How do they compare to
each other?
2. Does the data tell you anything about climate on a global scale? What causes
any similarities? Differences?
3. How much the temperature has actually changed? At the place on your Ice
Core graph representing the present day, write “OoC”. Now we can go back and
see how many degrees of temperature change there have been in the past. On
the axis measuring δ18O, write “+5OC” next to the minimum isotope value (3‰).
Now write “-10oC” next to the maximum isotope value (5.5‰).
4. The Last Glacial Maximum is the name for the most recent Ice Age. Based on
your Ice Core graph, when was the Last Glacial Maximum?
5.How much has temperature changed since then?
6. What’s the total temperature change between the Last Glacial Maximum and
the Last Interglacial (the last time of high temperatures)?
5
Part 2: Anthroprogenic Climate Change
You and your friends are tired of watching TV and playing video games,
so you decide to talk about global warming instead. It just so happens that you
have these three (3) figures lying around. The third figure is the famous
“hockey stick” graph. This graph shows temperature changes over the last
1000 years. Use these figures to answer the following questions.
The first figure shows CO2 values going back over 1000 years.
The second figure shows temperature and solar radiation. Solar radiation is
the energy that comes from the sun, and is responsible for keeping the Earth
warm.
6
The third figure is the famous “hockey stick” graph. This graph shows
temperature changes over the last 1000 years.
Use the previous three figures to answer the following questions.
7. Look at the CO2 graph. When does the amount of CO2 in the atmosphere begin to rise? Why
do you think CO2 begins to rise so quickly at that time? (Hint: what was happening historically at
this time?)
8. How does the record of CO2 compare to the temperature change shown in the hockey stick
graph?
9. If recent climate change were caused by changes in solar energy, what would the second graph
look like? Does it look like that now?
7
10. Based on these three figures, explain the behavior of temperature over the past thousand
years, and discuss possible causes for this behavior.
Another way to gauge historical climate change is to look at geologic features and how they’ve
changed over time. One such method is the study of glaciers. Glaciers are currently found only in
high mountains and in extremely northern areas. However, during periods of cold climate, glaciers
can form at lower and more southern locations. By observing geologic features of glacial areas, you
can infer how far the glacier had advanced or retreated in the past, which can give you clues about
temperatures.
Following this page is a map of the Nisqually Glacier, on Mt. Rainier, Washington. Nisqually Glacier is
located on the southern side of the mountain, and flows south toward the Nisqually River Bridge.
The position of the glacier’s terminus (downhill end; the “front” of the glacier) has been recorded by
geologists since 1857. The map you will be looking at shows the position of the terminus as it has
moved over the past 150 years.
Fill in the data chart by measuring the position of the terminus with a ruler and converting the
distance to kilometers. Then plot your data on the graph to the right of the chart. Once the points
have been plotted, connect them with a line. (NOTE: start at 1994, and skip every other year)
11. How has the position of the glacier’s terminus changed over time? What does this suggest
about the temperature over this time period?
12. How does your glacial record compare to the average land surface temperature shown in the
plot below your graph?
13. Do you think that the Nisqually Glacier can be used as a global thermometer for measuring
climate change? Why or why not?
8
9
10
A way to gauge historical anthropogenic climate changes is to look at fossil assemblages (multiple proxies) from
sediment cores prior to human influences. Biscayne Bay is a large (428 square miles) subtropical estuarine
ecosystem that began forming approximately 3200 years ago as sea level rose and flooded southern Florida.
Throughout most of its history the pristine waters of the bay supported a rich and diverse marine fauna and flora
and the bay waters served as a nursery for the adjacent coral reef ecosystem. In the 20th century, urbanization of
the Miami-Dade area profoundly affected the environment of the bay. Construction of power plants, water
treatment plants, solid waste sites, and large scale development along the shoreline stressed the ecosystem.
Demands of the population for reliable freshwater supply and flood control led to the construction of extensive
canal systems throughout south Florida. The current massive effort to restore south Florida lists restoration of the
timing, quantity and quality of the natural flow of freshwater as one its primary goals. Before restoration can
occur, however, the baseline conditions of the environment prior to significant human alteration must be
established and the range of variation within the natural system must be determined.
Cores from Black Point were taken on a sand bar at the mouth of an inlet just north of Black Point (Figures on next
page). The Black Point area has undergone significant change in the 20th century. Two canals, Goulds Canal and
Black Creek Canal, enter the bay just south of Black Point and a long (>3000 m) channel leads into the canals. A
water treatment and solid waste site (known as “Trash Mountain”) are located near the mouth of the canals. The
aerial photos show that the area west of the shoreline north and south of Black Point already was cleared and
partitioned for farming by 1940. Farming currently is still going on southwest of the site, but developments are
rapidly taking over the farm land. The shoreline around Black Point, however, has actually become more forested
since 1940, due in large part to its location inside Biscayne National Park.
Following this page is a plot of the changes in salinity and environment north of Black Point as
indicated by percent abundance of key ostracode, mollusk, and foraminfera indicators and Mg/Ca of
ostracode shells plotted against depth in cm, from Black Point North core (GLW603-BPN-A).
Calendar year is indicated on right. Use this plot to investigate how this portion of the bay has
changed over the last ~3,000 years.
14. In the lower portion of the core (60 – 80 cm), what type of salinities are indicated?
15. At what depth intervals are the highest salinities indicated?
16. There were small freshwater events prior to 1900 (indicated by fresh and brackish water
species), but Hydrobiids abundance increases by an order of magnitude after 1950. Why do you
think that the abundance of other low salinity proxies (Candona, Heterocypis, Cypideis, etc.) did
not return to pre-1900 levels?
17. Can humans restore ecosystems to the way they were before massive engineering? Why or
why not?
11
12
/30
Name: _______________________________
Section: ______________________________
Lab: Rivers & Streams
Introduction:
In this lab you will apply your topographic map reading skills to learn how streams carve and shape the
surface of the Earth. All water flowing in a channel is called a stream, whether it is as large as the
Amazon River or as small as the smallest creek. Streams are highly efficient agents of erosion and may
move more material after one storm in an arid region than wind does in an entire year. During this
laboratory you will explore why not all streams behave the same way and how streams can produce very
different landscapes.
Driving Question: How does running water shape the Earth?
Learning Objectives: Upon the successful completion of this laboratory, you should be able to:
1)
2)
3)
4)
Interpret topographic contour lines to measure gradients and relief; be able to identify hills,
basins, ridges, valleys, steep slopes and gentle slopes
Determine stream flow direction, delineate a watershed, and describe the differences
between a glacial valley and a stream valley.
Determine stream gradient and sinuosity from a topographic map, interpret stream valley
profiles, and explain correlations between a stream’s characteristics and the shape of the
valley it creates.
Construct and/or interpret topographic profiles and streams profiles and accurately
calculate vertical exaggeration.
Part I: Understanding How Streams Work
All streams operate according to a few simple principles regardless of their size.
*Water in streams flows downhill because of gravity.
*Streams typically flow in a well-defined channel, except during floods when the water overflows the
channel and spills out across the surrounding land.
•The motion of water gives a stream kinetic energy, enabling it to do the geologic work of erosion and
deposition. The amount of energy depends on the amount of water and its velocity, so, big fast-flowing
streams erode more than small, slow flowing streams.
•Kinetic energy allows a stream to transport sediment, from the finest clay particles to the largest
boulders. These particles slide or roll on the bed of the stream or are carried in suspension within the
water.
•The flow of water erodes unconsolidated sediment from the wall and bed of the channel, which can
abrade solid rock.
•Streams deposit sediment when they lose kinetic energy by slowing down (or evaporating). The heaviest
particles are deposited first, then the smaller grains, as the energy wanes.
Stream Channel = the area within which the water is actually flowing.
Stream Valley = the region within which the stream has eroded the land.
In some cases the channel completely fills the bottom of the valley; in others, the channel is much
narrower than the broad valley flow. Just as some valley walls are steep and others are gentle.
Complete ALL of EXERCISE A as your pre-lab assignment!
Exercise A. Use the pictures below to compare and contrast the Yellowstone River (A) and
Cascapedia River (B) by answering questions 1-8 to the best of your ability. Use the pine trees as a
method for scaling the pictures. You might also find it helpful to review the PDF in color on Sakai.
A.
B.
1.) Which stream has the wider channel?
2.) Which stream has a broader valley?
3.) Which stream has the most developed valley walls?
4.) How are valley width and channel width related? (LOOK at the pictures!)
5.) Which stream has a straighter channel?
Sinuous?
6.) Which stream is flowing faster?
How do you know?
7.) Which stream has the highest gradient?
8.) How can you tell that B had more energy at one time in the past?
Where did this energy come from?
Exercise A
*Dental floss or string should be used to measure stream length. A ruler will be used to
measure straight-line distance.
Base level is the elevation of the mouth. It is the lowest elevation that a stream
can erode down.
Exercise B. Compare the course of the Cane River between points A & B with that Shateen
Branch between points C & D .
1. Complete the table below using the Mt. Mitchell 7.5 quadrangle. (7pts)
Cane River
Shateen Branch
Channel Length (mi)
Straight Line Length (mi)
Sinuosity
Highest Elevation (ft)
Lowest Elevation (ft)
Vertical Drop (ft)
Gradient (ft/mi)
(2) What is the apparent relationship between a stream’s gradient and whether it
has a straight or meandering channel? (2pts)
_________________________________________________________________
_________________________________________________________________
(3) Test this hypothesis by examining three topographic maps of western North
Carolina river reaches. While closely located geographically, the French Broad, North
Fork Catawba, and the Linville river reaches have remarkable different valley
characteristics. Complete the table below to compare these three rivers. When
determining lengths and elevation, be aware that each map has a different scale and
contour interval. (10pts)
*These maps were developed entirely from a digital elevation model (DEM) based on light detection and ranging
(LIDAR) elevation measurements. LIDAR DEM’s are highly accurate, with elevation errors less than 1 ft. North
Carolina is unique in having costly statewide LIDAR DEM data, which was obtained due the high death toll and
monetary damage that resulted largely from freshwater flooding during Hurricane Floyd in 1999.
(4) Did this set of maps support your hypothesis about the relationship between
meandering (sinuosity) and gradient? Explain. (2pts)
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
(5) What is the apparent relationship between stream gradient and the shape of a stream valley? (2pts)
________________________________________________________________
________________________________________________________________
________________________________________________________________
(6) Now apply what you have learned to the streams in Exercise A. Which probably has the steeper
gradient—Yellowstone River (A) or Cascapedia River (B)? Explain your reasoning. (2pts)
________________________________________________________________
________________________________________________________________
________________________________________________________________
Part III: Interpreting Stream Valley Types
The Yellowstone and Cascapedia Rivers from Exercise A illustrate the two most common types of
stream valleys: steep-walled, V-shaped valleys whose bottoms are occupied fully by the channel, and
broad, flat-bottomed valleys much wider than the channel and within which the stream meanders
widely between the valley walls.
When water is added to a stream in a V-shaped valley, the channel expands and fills more of the
valley. When more water enters a stream with a broad, flat valley and a relatively small channel, it
spills out of the channel onto the broad valley floor in flood. Sediment carried by the flood water is
deposited on the flood plain, and other depositional and erosional features can be recognized easily on
topographic maps or photographs.
Stream valley shape is highly varied as a result of the a stream’s power (erosive force controlled by the
gradient and discharge of the stream) and the resistance of the underlying bedrock. The stream
channel is the area within which the water is flowing, where as a stream’s valley refers to the region
within which the stream as eroded the land. In some locations the channel completely fills the bottom
of the valley,; in others, it is much narrower that the broad valley floor.. Some valleys are steep and “v”
shaped forming canyons, while others are gentle.
Figure 10.7 Steep, V-shaped valley:
Vertical erosion carves the channel and
valley downward vertically
(large blue arrow), producing steep
valley walls. Mass wasting (slump,
creep, landslides, and rock falls)
reduces slope steepness to the angle of
repose (curved arrows) and widens the
top of the valley (dashed arrows).
Figure 10.7b Broad, flat-bottomed valley:
As the stream meanders, it widens the
valley (arrows). Mass wasting gentles the
slopes of the valley walls as in (a).
Oxbows mark the position of former
meanders.
Geologists compare stream valley profiles is by calculating the valley width to depth ratio. This
ratio is calculated by dividing the width of the river valley by the change in valley depth (high
point-low point) . The ratio is a unitless number, so, you will be able to directly compare the three
streams.
Exercise C.
1. Now you will apply the information you have just learned to the stream valley profiles
of the three western North Carolina rivers you examined earlier by completing the River
Valley Profile Comparison Chart. You will need to reference the set of stream valley
profiles that your TA has provided. (10pts)
Please Note: Different scales were used to construct the valley profiles, so you will need to begin by
determining how much each of the stream valley profiles has been vertically exaggerated.
NC River Valley Profile Comparison Chart
Parameter/
Name
French Broad
River
North Fork
Catawba River
Linville River
Vertical Exaggeration of Profile
Valley Width (Ft)
Highest Elevation in the Valley (Ft)
Lowest Elevation in the Valley (Ft)
Change in Elevation (Ft)
Valley Width to Depth Ratio
Now use the information you’ve compiled throughout the lab to answer the following
questions:
2. As stream gradient increases, do valleys become more narrow and steep-walled, or
wider and more shallow? Why? (2pts)
3. Will the valley width to depth ratio increase or decrease as gradient steepens? (2pts)
4. Accounting for the differences in vertical exaggeration, rank these three streams
from widest and most gentle to narrowest and steepest. (2pts)
5. What is then the apparent relationship between gradient, sinuosity, and the shape
of the cross-sectional profile of a stream’s valley? (2pts)
6. The Linville and North Fork Catawba rivers are located extremely close by; in fact,
the two profiles you examined are separated by less than five miles. The N. Fork
Catawba, though, has a lower gradient and much gentler valley slopes than the
adjacent Linville Gorge directly to the east. Given that the climate (precipitation) and
tectonic settings of these rivers are nearly identical, what is a possible explanation for
the difference in valley shape? (2pts)
Part IV: Recognizing Stream Features
Natural levees are ridges of sediment that outline the channel. They form when a stream overflows its
banks and deposits its coarsest sediment next to the stream channel. Several generations of natural
levees are visible in the diagram above, showing how meanders change position over time. Point bars
form when water on the inside of a meander loop slows down, causing sediment to be deposited. At the
same time, erosion occurs at the outside of the meander loop, because the water moves faster. The result
is that meanders migrate through time, moving outward (toward convex side) and downstream.
Sometimes a stream will cut-off a meander and straighten itself. This leaves a meander scar that may
fill with water and form an oxbow lake.
Exercise D.
1. Label the following on the
picture: Point bar, cut-bank, &
oxbow lake. (1.5pts)
N
Part V: Understanding and Recognizing Drainage Basins
Streams are particularly effective agents of erosion because they form networks that cover much of Earth’s
surface. Rain falling on an area runs off into tiny channels that carry water into bigger streams and
eventually into large rivers. Each stream-from tiniest to largest—expands headward over time as water
washes into its channel, increasing the amount of land affected by stream erosion. Understanding the
geometric patters of stream networks and the way they affect the areas they drain is key to understanding
how to prevent or remedy stream pollution, soil erosion, and flood damage.
Figure 10.10
Drainage Basin: the
area drained by a
stream
Drainage Divide:
Highlands which
separate drainage
basins
Exercise E. Refer to the map and/or picture in the lab tutorial powerpoint to answer
the following questions.
(1) What drainage pattern is associated with the Mississippi River drainage basin? (1pt)
(2) What does that tell you about the materials that underlie the central part of the United
States? (1pt)
(3) What drainage pattern do you see to the east of this reach the Bighorn River? (1pt)
Name:
40
+
15
Section:
EQ Certificate
Earthquakes & Seismic Waves Lab Packet
Introduction:
Earthquakes occur because of a sudden release of stored energy. This energy has built up over long periods
of time as a result of tectonic forces within the earth. Most earthquakes take place along faults in the upper
25 miles of the earth’s surface when one side rapidly moves relative to the other side of the fault.
This sudden motion causes shock waves (seismic waves) to radiate from their point of origin called the
focus and travel through the earth. It is these seismic waves that can produce ground motion which people
call an earthquake. Each year there are thousands of earthquakes that can be felt by people and over one
million that are strong enough to be recorded by instruments. Strong seismic waves can cause great local
damage and they can travel large distances. During this laboratory you will learn howgeoscientists
collect and interpret seismic data to locate and measure earthquakes.
Driving Questions: Where do earthquakes primarily occur and why ?
Learning Goals: Upon the successful completion of this laboratory, you should be able to:
▫Explain what an earthquake is, identify the difference between the focus and epicenter, and differentiate
between the four types of seismic waves.
▫ Locate an earthquake epicenter by using a seismogram and Travel-Time graphs.
▫ Differentiate between the Mercalli Scale (intensity), the Richter Scale (magnitude), and seismic moment
scale; determine the magnitude of an earthquake by interpreting seismic data.
▫ Recognize and explain common earthquake hazards that occur during and after the seismicevent.
Directions: Answer of each of the following questions to the BEST of your ability. You will need to refer
to the Earthquakes Tutorial PPT posted on Sakai and associated websites to complete this packet.
A. Earthquake Basics (2pts)
1.The ( hypocenter / epicenter ) is where the seismic waves originate inside the Earth,
while the ( hypocenter / epicenter ) is the on the surface and is the site of the greatest
ground motion and damage. (1pt)
2. What is the cause of most earthquakes? (1/2pt)
3. Identify 1 cause of earthquakes, not related to plate tectonics. (1/2pt)
B. Understanding & Interpreting Seismic Wave Data (11pts)
4. What is the difference between body waves and surface waves? (1pt)
5. Which body waves (P- or S-) have the greatest velocity? (1pt)
6. Do body waves or surface waves cause the most structural damage to buildings? (1pt)
7. What is the amplitude of the largest seismic wave shown in the Figure 1 ? (1pt)
mm
8. Identify the arrival of the 1st P-wave and 1st S-wave on the seismogram in Figure 1 (2pts.)
1st P-Wave =
sec
1st S-Wave =
sec
10. Do seismic waves strengthen or weaken as they move away from the focus? (1pts)
11. A seismogram is composed of signals from what other components? (1.5pts)
,
, and
.
12. What are the two main problems seismologists solve? (1pt)
&
13. How would you find the Earth’s structure if you were given a seismogram, the instruments signal,
and knew that the source was an explosion? (1.5pts)
C. Earthquakes and Plate Tectonics (9pts)
14. Where on Earth do most earthquakes occur? (1pt)
15. Do most earthquakes have shallow, intermediate, or deep foci ? (1pt)
16. At which type of plate boundary are most intermediate and deep focus earthquakes occurring? (1pt)
____________________________
17. History shows that earthquakes occur in the same general patterns year after year, principally in 4
teconic zones of the earth. What are these 4 tectonic zones and where are they located? (4pts)
A:
B:
C:
D:
18. Where do most earthquakes occur in the US? Why? (1pt)
19. “Intraplate” earthquakes occur inside of plates, away from tectonic boundaries. Do you see any
on the map of the US? If so, identify these areas. (1pt)
D. Locating Earthquake Epicenters ( 8pts)
At any seismic station, we can determine the distance of an earthquake from the seismic station using a
travel-time curve for the seismic station. Travel-time curves are developed at each seismic station by
plotting the distance of a known earthquake from the past, and the first arrival times of the P- and Swaves of that earthquake. Answer 20 & 21using the Travel-Time Graph in Figure 2.
20.Look at the difference between the S-wave and the P-wave curves. What is the difference (in seconds)
between the S-wave first arrival and the P-wave first arrival when an earthquake is at a distance of 100
KM away? (1pt)
seconds
21.Notice the S-P curve. This is called the S-P l ag time curve. It is just a plot of the difference between
the first arrival of the S-wave and the first arrival of the P-wave. Use the S-P lag time curve to find the
difference of the first arrival of the S- and P-wave when an earthquake is at 600 KM away from a
seismic station . (1pt)
seconds
22.What do you notice about the difference between the first-arrival of the S-wave and the first
arrival of the P-wave as the distance of the earthquake epicenters get further and further away?
Correctly complete the statement below. (1pt)
23. The greater distance away from the earthquake focus a seismic station is the (larger / smaller) the
S-P time interval will be. (1pt)
24. Can you determine the direction to the epicenter using data from 1 seismometer?
Why or why not? (1pt)
25. Why can’t you use only two seismic stations to get the distance to the epicenter? (1pt)
26. Circle the following information you must have to determine the location of an earthquake. (1pt)
a. Wave amplitude
b. S-P time interval
d. the velocity of the seismic waves
c. the type of rock the wave is traveling through
e. data from at least three seismic stations
27. Which type of seismic wave is the most efficient at transmitting energy? WHY?(1pt)
E. Measuring Earthquakes (5pts)
Using the nomogram and seismogram below, answer questions 28-29.
28. What is the magnitude of an
earthquake if the amplitude of the
seismic wave is 2 mm and the S-P
time interval is 10 secs? (1pt)
29. Why is the Richter scale no longer widely used by geoscientists? (1pt)
30. What parameters allow the Seismic Moment scale to be more accurate than the Richter Scale? (1pt)
31. What is the difference between magnitude and intensity? (2pt)
F. Identifying Earthquake Hazards (5pts)
32. T or F. Ground shaking is the most dangerous earthquake hazard for humans. (1pt)
33. T or F. Tsunamis only occur as result of underwater earthquakes. (1pt)
34. T or F. Liquefaction occurs when unsaturated, unconsolidated sediment is exposed to ground vibration.
35. Describe how earthquakes can cause destruction, both during and after an earthquake (2pts)
Remember to attach a copy of your EQ Certificate to this packet before turning it in!
Below is a seismogram that shows the arrival time of a seismic wave in secondson
the x-axis, and the amplitude of the wave over time.
Figure 1
Figure 2
/30
Name: _______________________________
Section: ______________________________
Lab 05: Introduction to Topographic Maps
Introduction:
Maps that deal with the surface changes on the earth are called topographic maps. Topographic
maps provide a detailed representation of the natural and man-made features of the earth’s surface.
The main characteristic of such maps is the representation of the three-dimensional terrain or relief
of the surface of the earth by the use of contour lines. During this laboratory we will look at how
topographic maps are created, what information they contain, how they can be used to compare
and contrast geologic landscapes and points of interest.
Driving Question: How to identify, describe, and interpret the topographic features of a location.
Learning Objectives: Upon the successful completion of this laboratory, you should be able to:
1)
2)
Read and interpret symbols on a USGS 7.5 minute topographic quadrangle.
Use a map scale to determine distance on a map.
3)
Interpret topographic contour lines to measure gradients and relief; be able to identify hills,
basins, ridges, valleys, steep slopes and gentle slopes
Construct topographic profiles and accurately calculate vertical exaggeration.
4)
Lab 05 Pre-Lab Assignment: Complete ALL of the Part I Exercises !
Part I: Understanding Contour Lines
The shift from a two to three dimensions involves the use of contour lines, lines on a map that connect all points of
equal elevation above sea-level. Contour lines always connect points of equal elevation. If a given contour line was
500ft and line immediately down slope was labeled 480ft, then we would say there was a 20ft difference between
the lines. This difference is termed the contour interval.
The contour interval chosen for your map will depend on how flat or hilly the region is (ie., how much map relief
is present, relief being the difference in altitude between the high points on the map and the lower points.) Mapping
Mt. Everest in 5ft contours would be silly, as would mapping the nearly flat surface of western Kansas in 100 ft
contours.
There are two general contour line styles on a topographic map. One is printed in a darker and wider line and is
the index contour. An index contour normally occurs every fifth elevation interval and is labeled frequently.
Use the index contour to find general elevation of the map area of interest.
In areas of low relief, contour intervals might be small, 5 or 10ft between the lines, while in regions of tall
mountains the contour interval might need to be 20-50 ft. The intent is to provide the smallest contour interval
that will yield the maximum information.
Between index contours are lighter and thinner lines, which are ordinary contour lines. These are seldom
numbered, but by noting the elevation of the index contour above and below the line in question, you can
determine the elevation of an unknown point.
1. Apply what you have learned to answer the following questions.
a.) Using a contour interval (C.I.) of 20 ft, label each contour. (1/2pt)
b.) What do the extra heavy lines indicate?
(1/2pt)
c.) What are the thinner lines? (1/2pt)
d.) What is the index contour interval?
(1/2pt)
Contour lines do not cross.
2. Apply what you have learned to answer the following questions.
A. What is the contour
interval for this map? (1/2pt)
B. What is type of landscape feature is shown?
C. How do you know?
(1/2pt)
(1/2pt)
D. If the contour interval is 20ft, what is the elevation of the spot marked X?
(Answer should be recorded as a range!) (1/2pt)
E. What is the elevation of the top of this feature?
(1/2pt)
F. What topographic feature is depicted? How do you know this? (1/2pt)
G. What is the highest elevation shown? (1/2pt)
H. What is the lowest elevation shown? (1/2pt)
I. What is the total relief of this map?
(1/2pt)
J. What direction is the stream flowing?
K. How do you know?
(1/2pt)
(1/2pt)
End of Pre-Lab
Assignment
Part 2: Understanding Topographic Quadrangles
We will practice topographic map reading and interpretation by looking at two maps created by the United
States Geological Survey (USGS): (1) the Mount Mitchell and (2) the Menan Buttes Quadrangles.
Definitions:
*Relief is the difference in elevation between two points. Total relief is the difference in elevation
from the minimum elevation in an area to the maximum elevation in an area
*Gradient is the relief between two points divided by the distance between the two points. In this lab
we express gradient in ft/mile.
*Landscape dissection refers to the degree to which rivers or other agents of erosion have incised into
the landscape. Highly dissected landscapes implies a long time span for erosion to sculpt the planet’s
surface.
*Benchmark (BM) is a location whose elevation and horizontal position has been surveyed as
accurately as possible. Benchmarks are designed for use as reference points
(1/2pt)
4.) Based on this answer, what type of rock outcrops in the northwest portion of the quad?
Igneous / Sedimentary / Metamorphic (circle one)
(1/2pt)
Part 3: Drawing a Topo Profile
Name: ____________________________
How to create a topographic profile:
1)
2)
3)
4)
5)
6)
Label the contour lines that cross the B-B’ line.
Get out a strip of scratch paper and line-up the scratch paper with the B-B’line.
Working from left to right, make a tick mark on your scratch paper where it crosses a
topographic contour line or stream.
Label each tick mark with the elevation of the corresponding contour
Line up your tick marked paper with the bottom of the graph and, beginning with the elevation
on the left hand side of the paper, go directly up from that tic mark to make a small dot at the
corresponding elevation.
Once you have transferred all of your tick marks to your graph, connect the dots with a
smooth curve.
Topo Profile of Battle Creek B-B’ Line
(8pts)
300
(2pts) :
_________________x
Vertical Exaggeration Practice Problems
Use the figure to the left and the information
provided to calculate vertical exaggeration for
(2pts each)
the following map scales:
A.) 1:24000
B.) 1:7200
/30
Name: _______________________________
Section: ______________________________
Lab #5: Discharge, Floods, & Groundwater
Introduction:
During the first half of laboratory 7 we will continue our investigation of surface water. This week you
are going to learn how we quantify stream discharge using the continuity equation and stream
hydrographs. Then you will learn how geoscientists calculate flood recurrence intervals and then use
the information to generate flood risk assessment maps.
The second half of the laboratory we will investigate what happens when water is absorbed into the
ground and is called groundwater . Groundwater has to drip from one pore space to another, therefore it
has much lower kinetic energy than stream water and cannot carry the particles with which streams erode
bedrock by abrasion. As a result, groundwater can only erode chemically. We will examine how
groundwater erosion (underground activity) can influence landscape formation at the surface. We’ll end
the lab by discussing groundwater resources and pollution problems.
Driving Question: How are stream’s quantified? What is a flood probability?
How does groundwater shape the Earth?
Learning Objectives: Upon the successful completion of this laboratory, you should be able to:
1.
Quantify the volume of water (discharge) moving through a stream and determine the flood
frequency/recurrence interval for a stream data set.
2.
Recognize landscapes formed by groundwater (Karst Topography) and interpret groundwater
flow direction from the topographic features.
3.
Use topographic map data and/or well data to map groundwater pollution plumes.
4.
Identify the location of a water table and the saturated vs unsaturated zone.
5.
Compare and contrast porosity and permeability and identify these properties in natural
materials.
Part I: Calculating Stream Discharge
The volume of water flowing past a certain point along a river in a given time is its discharge and is given in
units of volume per time (often m3/s or ft3/s). Runoff is simply the discharge of a river divided by its
drainage area and is given in units of length per unit time (often m, mm, in per year or month) and is useful
in comparing the amount of water flowing through rivers to the incoming precipitation.
Discharge (Q) of a river is calculated using the equation
Q = wdv
with the average depth (d), velocity (v), and width (w) of the stream channel. The United States Geological
Survey (USGS) maintains an extensive network of stream gauges that provide continuous discharge
measurements online at waterdata.usgs.gov. Periodically, the USGS measures average depth, width, and
velocity at gauging station locations to verify their accuracy; these measurements are available online as
well.
Discharge in a stream is not just determined by water flowing over the surface; if it was, there would be
no water at all in rivers during dry periods. Water contained in the ground also flows downhill towards
stream channels; the discharge in a stream that results from this groundwater contribution is called
baseflow (although some channels do dry out during dry months; these are called ephemeral streams).
Baseflow represents the minimum discharge in a channel during a given time of year. Discharge is
represented by hydrographs (Figure 3)—plots of river discharge over a period of time. The timing and
magnitude of discharge depends largely on local climate (seasonal variation in precipitation type and
patterns, temperatures, etc). Discharge in a river is often very closely related to its drainage area—larger
basins have more area contributing overland and groundwater flow than smaller ones.
Figure 3: 2013 Hydrograph of the Potomac River near Washington, DC
Exercise A
Use the 2013 Potomac River Hydrograph to answer the following questions.
(1) What was the peak discharge of the Potomac River in 2011? ____________ft3/s
(2) How many months had a peak discharge greater than 100,000ft3/s ? __________
(3) What is the approximate annual baseflow of the Potomac River? ________ ft3/s
Use the Crab Tree Creek (Fig 2)and Haw River (Fig 3) Hydrographs to answer the following
questions :
(4) What is the approximate baseflow of Crabtree Creek in January ? (1pt) ______ ft3/s
(5) What is the approximate baseflow of the Haw River for this time of year? (1pt)
(Hint: look at the beginning of the month, which consisted of a dry period!) _________ ft3/s
The USGS surveyed the Haw River near Bynum, NC (drainage area: 1275 mi 2) between
January 11-16, 2015, and found the following characteristics:
Width: 305.0 ft
Mean depth: 7.9 ft
Mean velocity: 1.72 ft/s
(6) What was the average discharge for the Haw River? (1pt) _________ ft3/s
The USGS also surveyed Crabtree Creek (drainage area: 121 mi 2) in at US Route 1 in
Raleigh, NC between January 11-16, 2015 and measured the following stream
characteristics:
Width: 70.5 ft
Mean depth: 2.05 ft
Mean velocity: 1.97ft/s
(7) What was the average discharge for the Crab Tree Creek? (1pt) ______ft3/s
(8) Which stream has the higher baseflow and average discharge in January of
2012? Crabtree Creek or the Haw River? What accounts for this difference? (2)
Figure 2: January 2015 hydrograph of Crabtree Creek at US Route 1 at Raleigh, NC
Figure 3: January 2015 hydrograph of the Haw River near Bynum
(9) Which hydrograph (below) do you think represents a river dependent on
rainfall, and which represents a snowmelt-dominated river? (1pt) A or B
Not all discharge in rivers is due solely to rainfall and baseflow. In high elevations or latitudes with
substantial snowpack, discharge in rivers can be dominated by melting snow, which produces
substantially different runoff timing. Two hydrographs from North American rivers appear in Fig.6.
Part II: Flood Recurrence Intervals
For each river, it is possible to determine the frequency of floods of a given magnitude. This is
accomplished by calculating the recurrence interval (T). We can also calculate the probability of that a
flood of a certain magnitude will occur in a given year. Given a record of the highest flows for n number of
years with each year’s rank m (from 1 to n; highest to lowest discharge), we use the equation
T =
( n + 1)
m
to calculate the recurrence interval T for each event. T is then plotted on the x-axis of semi-logarithmic
paper To determine the percent probability that a flood of a certain magnitude will occur in a given year,
we use the equation
P =(1/T) * 100
EXERCISE B.
Table 1 contains the peak discharge for the last 25 years (n then is 25) for the North Fork of the French
Broad River at Rosman, NC. Ranks, recurrence intervals, and percent probabilities have been
calculated for most; for those that have not, determine the rank of each discharge and use the above
equations to calculate the recurrence interval and probability of each. Then, plot T on the x-axis of the
provided paper and discharge Q on the y-axis. Note that the x-axis of the graph is on a logarithmic scale—
this allows us to display the data in a linear fashion. Next, draw a straight best-fit line through the data
points; this will allow you to determine the expected discharge of 50 and100-year floods and the recurrence
intervals for floods of given magnitudes.
(2) The information above was used to generate a a flood frequency
curve for NF French Broad River (projected). Use the flood frequency
curve to answer the following questions.
Part III: Groundwater Basics
Pore space
filled with air.
Pore space
filled with
water.
Water Table: The level below which the ground is saturated with water.
Porosity – Amount of “free space” or pore space in a rock or in sediment. Room
between grains.
Permeability – Connectivity of pore space/free space in a rock or in sediment.
Exercise C: Porosity & Permeability Demonstration
Properties of material that might affect water flow
(1) Complete the chart below during the demonstration.
Observation
Container 1
Container 2
Container 3
Grain size
Small
Medium
Large
Small
Medium
Large
Small
Medium
Large
Poor
Moderate
Good
Poor
Moderate
Good
Rounded
Sub-rounded
Sub-angular
Rounded
Sub-rounded
Sub-angular
High
Moderate
Low
High
Moderate
Low
High
Moderate
Low
High
Moderate
Low
Sorting
Poor
Moderate
Good
Grain shape
Rounded
Sub-rounded
Sub-angular
Porosity
High
Moderate
Low
Permeability
High
Moderate
Low
(2) Match each of the following rock type with its characteristics. (2pts)
Rock type
Characteristics
Granite
Limestone
Sandstone
Shale
Dissolves in weak acid
Has high porosity, high permeability
Has high porosity, no permeability (impermeable)
Has low porosity, no permeability (impermeable)
(3) What is the difference between porosity and permeability? (2pts)
Part IV: Groundwater Landscapes = KARST TOPOGRAPHY
Landscapes Produced by Groundwater
Sinkholes – form when underground cavities dissolved by groundwater grow so large that there is not
enough rock to support the ground surface
Groundwater dissolves
limestone, forming caves
Caves grow, decreasing
support of ground surface
Ground collapses, forming
steep-sided sinkholes
Karst towers – what remain when the rock around them has been dissolved
Water infiltrates
along
intersecting
fractures.
Limestone is
dissolved
along fractures
The general ground surface is
Lowered by solution; limestone
Remaining between fractures
Stands above surface as karst
towers.
Karst valleys – form when several large sinkholes develop along an elongate fracture
How a cone of depression forms:
1) Water is pumped out of the aquifer
2) Water flows downward to replace the empty pore spaces from where water was removed
3) The water table around the well lowers
Exercise D. Apply what you have learned to answer the following questions to the best of your ability.
1. Which statement about recharge areas is NOT true? (1pt)
a. Recharge areas typically are elevated with respect to neighboring areas.
b. Recharge areas are regions of relatively high precipitation.
c. Recharge areas are the same as discharge areas.
d. Recharge areas are areas where water infiltrates the sediment from above.
2. Pumping vast quantities of water locally ____________. (1pt)
a. raises the local water table
b. lowers the local water table, forming a cone-shaped depression
c. lowers the local water table, forming a cylindrical depression
d. does not affect the water table
3. Extensive pumping of fresh groundwater from a coastal aquifer can induce _______. (1pt)
a. saline intrusion; with time the well will start to deliver saline water
b. saline expulsion; with time the fresh water/saline water interface within the aquifer will
be pushed downward and seaward
Exercise E. Groundwater Plume Mapping
are released into the ground when corroded gas tanks leak and are indicators of soil and
groundwater contamination. Concentrations greater than 50 parts per million (ppm) are
considered dangerous to human health. The contamination data as shown in red numbers on
Figure 12.13.
(1) Make a contour map of the soil contamination level using a 10ppm contour interval. THIS IS
NOT A MAP SHOWING ELEVATION, BUT, THE RULES ARE THE SAME. You will contour to
reveal contamination plumes. (8pts)
Color Code the map to show levels of potential danger:
*Red- Values 50ppm
* Yellow- Values between 30-49ppm
* Green-Values between 10-29ppm
* No color-Values less than 9ppm
(2) Does either gas station have a leakage problem? Explain your conclusion. (2pts)
(3) In what direction does the local groundwater flow? How do you know? (1pt)
(4) Which homes will be the next to feel the effects of the gasoline leakage? (1pt)
(5) Did your research uncover any additional problems? If so, explain them. (2pts)
Figure 12.13
Hint: Make a contour map of the soil contamination level using a 10ppm contour interval. THIS IS
NOT A MAP SHOWING ELEVATION, BUT, THE RULES ARE THE SAME. Color code your
map as directed below.
Color Code the map to show levels of potential danger:
*Red- Values 50ppm
* Yellow- Values between 30-49ppm
* Green-Values between 10-29ppm
* No color-Values less than 9ppm
Name: ___________________________
Section: ________________
GEOL 101 Lab Final Exam Review Packet (40pts)
We want you to perform your best, so, we’ve decided to award you 40 points
an incentive for you to complete the entire review packet!
You will be able to “check” your Review Packet answers by using the Answer Key.
GEOL 101 Lab Final Exam Information
The exam will be through ‘Tests & Quizzes’ on the course Sakai site.
A. Conceptual Understanding (40pts)
– 20 multiple choice questions
– Questions will mimic lab packets & skills worksheets.
B. Applied Application (Written) (40pts)
-Topo profile, VE, sea-floor spreading, hot spot track motion, density calculations.
– Questions will mimic lab packets & skills worksheets.
C. Applied Application (Maps) (20pts)
-Distance measurements, gradients, VE.
– Questions will mimic lab packets & skills worksheets.
Lab: Geologic Time
Driving Questions:
1. What is the geologic time scale and how is it organized?
2. How do geoscientists identify, describe, and interpret the geologic
history of an area?
Learning Objectives:
•
•
•
Be able to determine relative ages of rocks and geologic processes, and use this information to
interpret & construct geological histories.
Be able to define what an index fossil is and explain their significance in the organization of the
geologic time scale.
Understand how numerical age dating works and be able to apply absolute ages to geologic
materials and events.
The rock columns represent four widely separated locations, W, X, Y, and Z. Numbers
1, 2, 3, and 4 represent fossils. The rock layers have not been overturned.
1. Which numbered fossil best represents an index fossil?
(1) 1
(3) 3 (2) 2
(4) 4
2. Which rock layer is the oldest?
(1) tan sandstone (3) green shale
(2) gray limestone (4) black shale
3. Put the following in relative age order.
The half life of Uranium-235 is ~713 million years. A rock originally contained 36mg of U-235.
4. The
rock now contains only 9mg of U-235. About how old is this rock?
5.
Which two events produced the geologic unconformity in the rock record?
(1) intrusion of magma, followed by contact metamorphism
(2) intrusion of magma, followed by erosion of rock layers
(3) erosion of rock layers, followed by deposition of more sediments
(4) erosion of rock layers, followed by intrusion of magma
Lab: Applied Plate Tectonics
Driving Question: Layers, plates, & plumes, what makes the tectonic plates move around?
Learning Goals:
• Differentiate between ocean & continental crust, identify locations where oceanic crust is created or
destroyed.
• Describe how the distribution of volcanoes and earthquakes varies in relation to tectonic boundaries.
• Describe the relationship between age and the topography of the ocean floor relative to plate boundaries.
• Define the Theory of Plate Tectonics, identify the different types of plate boundaries and each of their
characteristic features, and explain the tectonic cycle.
• Calculate and explain how the rate of tectonic plate movement is determined through the interpretation
of paleomagnetic data at mid ocean ridges (sea-floor spreading rate) and through hot spot tracking.
1. How is the distribution of volcanoes and earthquakes related to plate
tectonic boundaries?
2. How is the age of the oceanic crust related to the bathymetry of the ocean
floor? (Hint: is older crust near a ridge or a trench?) Explain your answer.
3. Why isn’t continental crust subducted?
4.
5.
6.
7.
8.
9.
10.
(Select the best answer.)
Lab: Topographic Maps
Driving Question: How to identify, describe, and interpret the topographic features of a location.
Laboratory Learning Objectives:
By the conclusion of this laboratory you should be able to:
• Read and interpret symbols on a USGS 7.5 minute topographic quadrangle.
• Use a map scale to determine distance on a map.
• Interpret topographic contour lines to measure gradient and relief; be able to identify hills, basins,
ridges, valleys, steep slopes and gentle slopes.
• Construct topographic profiles and accurately calculate vertical exaggeration.
1.
2. What is the approximate location of Captain Cook?
3 . Calculate the vertical exaggeration for the profile below.
Map scale 1: 63,360
4. What is the contour interval for this map?
5. Determine the total relief of the map.
6. What is the distance from Basket Dome (X) to North Dome (Y)?
7. Draw a line from Tenaya Canyon to Basket Dome that would be a good path
for a hiking trail. This has to be made in such a way as to allow the general
population to complete the hike. Justify your answer below.
Lab: Rivers and Streams
Driving Question: How does running water shape the Earth?
Learning Objectives: Upon the successful completion of this laboratory, you should be able to:
• Interpret topographic contour lines to measure gradients and relief; be able to identify hills,
basins, ridges, valleys, steep slopes and gentle slopes
• Determine stream flow direction, delineate a watershed, and describe the differences between a
glacial valley and a stream valley.
• Determine stream gradient and sinuosity from a topographic map, interpret stream valley
profiles, and explain correlations between a stream’s characteristics and the shape of the valley it
creates.
1. Wide river valleys typically contain:
A. non-sinuous, slow-moving streams.
B. non-sinuous, fast moving streams.
C. sinuous, slow-moving streams.
D. sinuous, fast-moving streams.
2. Narrow river valleys typically contain:
A. non-sinuous, slow-moving streams.
B. non-sinuous, fast moving streams.
C. sinuous, slow-moving streams.
D. sinuous, fast-moving streams.
3. Stream gradient is calculated as:
A. straight-line distance / downstream distance.
B. downstream distance / straight-line distance.
C. relief / downstream distance.
D. downstream distance / relief.
4. All rivers and streams flow from the north to the south. (T or F)
5. When a stream intersects contour lines on a topographic map, the contour lines point:
A. Downhill.
B. Uphill.
C. To the north.
D. To the south.
6. The rule of V’s states that _________.
a. on a topographic map, contour lines that cross a stream form a V that
points downstream
b. on a topographic map, contour lines that cross a stream form a V that
points upstream
c. V-shaped valleys form in river systems with low gradients.
d. V-shaped valleys form in highly sinuous rivers
Lab: Stream Discharge, Floods, & Groundwater
Driving Questions:
How are stream’s quantified?
How does groundwater shape the Earth?
Learning Objectives: Upon the successful completion of this laboratory, you should be able to:
• Recognize landscapes formed by groundwater (Karst Topography) and interpret groundwater
flow direction from the topographic features.
• Use topographic map data and/or well data to map groundwater pollution plumes.
• Identify the location of a water table and the saturated vs. unsaturated zone.
• Compare and contrast porosity and permeability and identify these properties in natural
materials.
• Quantify the volume of water (discharge) moving through a stream and determine the flood
frequency/reoccurrence interval for a stream data set.
1. Sinkhole lakes form when:
A. Sinkholes fill with rain water.
B. Streams flow into sinkholes.
C. Sinkholes intersect the water table.
D. Karst towers erode completely.
2. You are working in an area with an important aquifer that has been contaminated by a
buried tank. You need to know the slope of the water table so that you can calculate how
quickly the contaminants will get to nearby wells. You measure the depth to water in two wells:
Well A has water at 649 m elevation; Well be has water at 937 m elevation. The two wells are 0.5
km apart. What is the slope of the water table (in m/km)?
3. The diagram below shows four tubes containing 500 mL of sediment labeled A, B, C, and D.
Each tube contains well-sorted, loosely packed particles of uniform shape and size, and is open
at the top. The classification of the sediment in each tube is labeled.
Water was poured into each tube of sediment and the time it took for the water to infiltrate
to the bottom was recorded, in seconds. Which data table best represents the recorded
results?
4. Use the Rio Grande Hydrographs to answer the following questions:
A. Was the river dry at any time(s)? List months and years.
B. What were the flows on June 18 on each of the years shown?
C. What causes these high flows at this time of the year?
D. Count the number of days in each of the three years the water
flowed over 3,500 cfs. This represents overbank flooding conditions
in area of Bosque del Apache National Wildlife Refuge just north of
San Marcial.
E. What causes the smaller peaks in late summer?
F. Which year had the highest flows during the late fall/early winter?
G. Why has the hydrograph changed over the century?
H. In this system, what effect, if any have the dams built in 1950 and
1976 had on river flow?
Flood probability is calculated by ranking different flood events. The largest discharge is r =1.
Recurrence Interval (RI) is the first step in calculating probability. It is how many years it takes for a flood
of this size to occur. It is calculated by dividing the number of years that the data has been collected (in
this case 11) +1 divided by the flood rank, r.
The formula is below:
5. Complete the Table (3pts). Then graph the data (2pt). After graphing the data, draw a line that “best “
fits the data. (1pt) Finally, use the Table and Graph to answer questions A –D (3pts total).
A. What is the probability of the greatest flood occurring again?
B. What is the probability of the smallest flood event
occurring again?
C. According to the “best fit” line on your Discharge vs
Recurrence Interval Graph, what is the predicted
discharge of a 20-year flood event?
D. According to the “best fit” line on your Discharge vs
Reoccurrence Interval Graph, what is the predicted
discharge of a 50-year flood event?
Discharge (ft3/sec)
Discharge vs. Recurrence I…
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