This is a lab , Need help with short anwsers and mutiple choices etcc . on this lab all together .
GEO 101 – Geologic and Tectonic History of New York City and Long Island
Laboratory
Student Name:________________________________
Geologic and Tectonic History of New York City and Long Island Laboratory
Purpose
The purpose of this lab is to become familiar with the geographical locations of the boroughs of
New York City and counties of Long Island. To understand the different rocks that make up these
regions, and where they are located and the geological history that led to their occurrence.
Learning Objectives
After doing this lab you will be able to:
1. Explain the geographic locations of the boroughs of New York City and the counties of Long
Island.
2. Explain the different rocks that make up New York City and Long Island.
3. Explain the geological and glacial history or New York City and Long Island.
4. Explain the different rock types that make up New York City.
Introduction: Geologic and Tectonic History of New York City and Long Island
The rocks that make up New York City and Long Island today have a long and varied history that
goes back over a billion years and represents some of the oldest rocks in North America. The
geological history of New York and Long Island occurred in seven main events.
1. The Grenville Orogeny: About 1.1 billion years ago continental landmasses collided to
form the supercontient Rodinia. The collision formed massive Himalaya style mountain
building event called the Grenville Orogeny. Later erosion of this mountain range exposed
the high grade metamorphic basement rocks that make up all of New York State. In New
York City, these ancient rocks are known as the Fordham Gneiss and are found in the
Bronx (Fig. 1)
Figure 1. Continental plate collision formed the Grenville orogeny 1.1 billion years ago
forming the supercontinent Rodinia.
2. Continental Breakup: Around 600 million years ago Rodinia separated at a divergent
plate boundary forming ancestral north America or Laurentia and the Iapetus Ocean basin
(Fig. 2).
Figure 2. Rodinia separated 600 million years ago.
3. Taconic Orogeny: 560 million years ago a volcanic arc (Taconic or Ammonoosuc
volcanic arc) formed a convergent boundary off the coast of Laurentia. Around 440
million years ago the volcanic arc collided with North America (Figs. 3 and 4).
Sedimentary and volcanic rocks from the ocean floor and continental margin were thrust
onto the Grenville basement rocks to form the Taconic Orogeny, the first of three mountain
building events that formed the Appalachian Mountains. The uplifted and exposed
remains of the high grade metamorphic rocks that formed the core of these mountains form
the rocks of New York City in Manhattan, Staten Island, Bronx, Queens and parts of
Brooklyn. These metamorphic rocks include:
a. Hartland Formation: 560 million year old schists formed from deep ocean
sedimentary rocks and volcanics derived from the Amonoosuc volcanic arc.
b. Manhattan Formaton: 560 million year old schists and amphibolites formed from
continental derived sediments and ocean floor volcanic rocks.
c. Walloomsuc Formation: 460 million year old schists and amphibolite with pyrite
and graphite.
d. Inwood marble: 460 million year old shallow reefs and carbonate platforms,
indicating a tropical, near-equatorial setting, close to the continental shoreline.
e. Serpentinite Suture Zone: A large fault zone on the ocean floor associated with
the Amonoosuc volcanic arc caused the formation of serpentinite rock that is seen
on Staten Island. This rock was later thrust onto the Laurentia continent.
Figure 3. (A) The Walloomsuc or Taconic volcanic arc off the coast of Laurentia (North America).
(B) The collision of the volcanic arc with North America to form the Taconic Mountains.
Figure 4. Paleogeographic map of Laurentia (North America) with the Taconic volcanic arc.
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4. Acadian Orogeny: 370 million years ago a second volcanic arc called Avalon collided
with and accreted to the growing continental margin of eastern North America. This set in
motion the formation of the Acadian Orogeny and the continent called Laurasia (Fig. 5).
Rocks from this collision event are not observed in New York City. However, further north
we find the sedimentary rocks from the development of the Catskill river delta with
sediments shed to the west of the mountain range.
Figure 5. The collision of the Avalon volcanic arc with North America formed the Acadian
Orogeny.
5. Alleghanian Orogeny: 270 million years ago the North American (called Laurasia)
continent collided with Africa (called Gondwanaland) closing the Iapetus Ocean and
forming the Alleghanian orogeny (Fig. 6). This collision was the third and final event that
formed the Appalachian mountain chain. Due to forming from the collision of two
continental landmasses, this collision produced massive Himalaya sized mountains. Today
the eroded remains of these mountains form along the east coast of North America
spanning over 3000 miles between Georgia in the south to and Maine in the north. Little
evidence from this event is recorded in the rocks of New York. However, steep folding and
small igneous intrusions in the form of mafic, granite and pegmatite dikes that form
abundant veins through the metamorphic rocks throughout the city are likely relics of this
collision event. Also, the tectonic collision led to the uplift of the Catskill river delta and the
formation of the Catskill mountain plateau.This collision also finalized the assemblage of
the giant supercontinent Pangea (Fig. 7).
Figure 6. The collision of the Africa with North America to form the Alleghanian Orogeny.
Figure 7. During the
Alleghanian
Orogeny, the super
continent Pangea
was formed.
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6. Continental Breakup: 225 million years ago Pangea started to breakup that led to the
present day configuration of continental. Around 180 million years ago a divergent plate
boundary formed along the east coast of North America which led to the formation of the
Atlantic Ocean (Fig. 7). Evidence for the breakup can be found along the western (New
Jersey) side of the Hudson River in the form of the Palisades sill, a mafic intrusive igneous
rock.
Figure 7. The breakup of the super continent Pangea was formed the Atlantic Ocean off
the coast of New York.
7. Cretaceous sedimentation: In Long Island, 70 million year old sediments were deposited
over the metamorphic basement rocks during the Cretaceous (coastal plains
sediments).The basal Lloyd Sand is overlain by the Raritan Clay, followed by the MagothyMatawan and Monmouth formations. These sediments are the source of several
groundwater storage aquifers on the island (Fig. 8).
Figure 8. A crosssection of Long
Island to show the
basement rocks,
sediments and
glacial rocks.
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Figure 9. Continental glaciers spread south as far as Long Island, NY 100,000 years ago during
the Pleistocene glaciation (left). Continental glacier cover today (right).
8. Pleistocene Ice Age. Large continental glaciers spread from the Arctic south to the New
York area about 100,000 years ago (Fig. 9). The mile-thick ice sheet traveled from
northwest to southeast (Fig. 10) and scoured the bedrock across York City producing many
erosional features (striations, eratics). The glacier halted and then retreated where Long
Island is today depositing mounds of till and outwash (Fig. 11) in two main moraines
(Ronkonkoma around 55,000 years ago and Harbor Hill around 18,000 years ago).
Sediment washed out from under the ice as it melted formed outwash to the south of both
moraines.
The Ronkonkoma moraine runs east to west along the spine of Long Island and the main
highway, the Long Island Expressway, runs along this spine. Route 25A runs along the top
of that Harbor Hill moraine on the Northshore of Long Island. The high elevations of
Queensborough Community College indicates its location on the Harbor Hill moraine.
Figure 10. The
glacier that
terminated on Long
Island flowed from
NW to SE and
deposited red-brown
till and outwash. (J.
E. Sanders, 1985).
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Figure 11. A crosssection from Connecticut
to Long Island showing
the terminus of
continental glacier
standing in what is now
Long Island Sound and
spreading outwash sand
and gravel southward to
bury the Upper
Cretaceous sediments
and basement rocks (J. E.
Sanders, 1985).
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Exercises Part I. Geography of New York City and Long Island — EXPLORE
Figure 12. The boroughs and waterways of New York City.
Question 1. On the map of New York (Figure 12), label the five boroughs: Bronx, Brooklyn,
Manhattan, Queens, Staten Island.
A. ____________ B. _____________ C. _____________ D. _____________ E. ___________
Question 2. What location is shown by letter F.
a. New Jersey
b. Long Island
c. The Hudson River
d. The Long Island Sound
e. The New York Harbor (Atlantic Ocean)
Question 3. What location is shown by letter G.
a. New Jersey
b. Long Island
c. The Hudson River
d. The Long Island Sound
e. The New York Harbor (Atlantic Ocean)
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Question 4. What location is shown by letter H.
a. New Jersey
b. Long Island
c. The Hudson River
d. The Long Island Sound
e. The New York Harbor (Atlantic Ocean)
Question 5. What location is shown by letter I.
a. New Jersey
b. Long Island
c. The Hudson River
d. The Long Island Sound
e. The New York Harbor (Atlantic Ocean)
Question 6. What location is shown by letter J.
a. New Jersey
b. Long Island
c. The Hudson River
d. The Long Island Sound
e. The New York Harbor (Atlantic Ocean)
Figure 13. Map of Long Island.
8. On the map of Long Island (Figure 2), label Brooklyn, Queens, Nassau County and Suffolk
County.
A. _____________ B. _____________ C. _____________ D. _____________
Part II – Geology of New York City — EXPLAIN
Step 1. View pictures of the rocks of New York City here:
https://pbisotopes.ess.sunysb.edu/reports/ny-city/
Step 2. Mark the locations of each of the rocks onto the geological map (Fig. 14).
Question 1. Using Figure 14 and the geology map of New York City by Brock and Brock (2001) at
the back of the packet, develop a legend for each rock unit use colored pencils. Mark each of the
rock units onto Figure 14.
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Figure 14. Map and rock units of New York City.
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Question 2. Apply the legend you have developed for your geology map of New York City (Fig. 14)
to Figure 15 below, that shows the tectonic setting of New York City about 500 million years ago
prior to the collision event that formed the Taconic Orogeny and rocks of New York City.
Figure 15. Tectonic setting of future New York City about 500 million years ago. The Ammonoosuc
volcanic arc was converging with the continental margin of Laurentia (North America)
Question 3. Apply the legend you have developed for your geology map of New York City (Fig. 14)
to figure 16 below, showing the position of rocks following the Taconic Orogeny collision that
formed the rocks of New York City.
Figure 16. The position of rocks following the Taconic Orogeny collision that formed the rocks of
New York City.
Question 4. Using your geology map which included rock ages (Fig. 14), schematic cross section
of the continental margin (Fig. 15), and collision deformation relationship diagram (Fig. 16),
interpret the geological history of New York City during the Taconic Orogeny.
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Question 5. Use Figure 17 to determine the approximate pressure, temperature and depth
conditions that the Manhattan schist and Fordham gneiss experienced when they were
transformed to metamorphic rocks during the Taconic Orogeny.
Table 2.
Rock
Pressure
(kilobars)
Manhattan Schist
8
Fordham Gneiss
9
Temperature (˚C)
Depth (kilometers)
Figure 17. The types of
metamorphic rocks that
form underground based
on the pressure,
temperature and depth
conditions.
Source:
https://openpress.usask.ca/ph
ysicalgeology/chapter/10-4metamorphic-facies-andindex-minerals-2
Part III – Geology of Long Island, NY
Question 1. Referencing the USGS geology map of Long Island (see back of lab packed), use
colored pencils to develop a legend for each rock unit on the map of Long Island, NY (Fig. 18).
Then mark each of the rock units onto the map below.
Figure 18. Map and rock units of Long Island.
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Question 2. Watch the video showing the formation of Long Island
https://www.youtube.com/watch?v=4UyocM9bDL4 and then briefly describe the geologic history of
the area.
Part IV Questions — EVALUATE
Question 1. Which of the five boroughs of New York City is an island.
Question 2. What was the name of the orogenic event that formed the rocks of New York City?
Question 3. In the table below list the rocks of New York City, their tectonic setting prior to the
Taconic orogeny, and their age (use Figure 15 to help).
Rock Name
Tectonic Setting
Age
Walloomsuc schist
Inwood Marble
Hartland schist
Manhattan schist and
amphibolite
Fordham gneiss
Question 4. Discuss why some of the older rocks of New York City are positioned over younger
rocks. Refer to Figure 15 and 16 to inform your answer.
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Question 5. Besides the Taconic orogeny, which other orogeny had an impact on the rocks of
New York City and what is the evidence?
Question 6. What rocks formed during the breakup of Pangea and the opening of the Atlantic
Ocean about 180 million years ago? At what location do they occur?
Question 7. How old was the continental ice sheet when it first covered the New York area during
the Pleistocene glaciation?
Question 8. In the table below, describe how and when the different rock units of Long island
formed.
Rock Unit
Age
Taconic Orogeny
Basement rocks
Cretaceous sediments
Ronkonkoma Moraine
Harbor Hill Moraine
Outwash
Question 9. How did the continental ice sheet lead to the formation of Long Island?
Question 10. On what rock formation is Queensborough Community College located?
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Map and rock units of Long Island.
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