9)The Hawaii hotspot produces mafic volcanoes while the Yellowstone hot spot produces felsic volcanoes, what does this mean for the relative explosiveness of these two volcanoes ie which would be more and which would be less explosive?
10) Looking at question 9 what is is about the chemical composition that makes one volcano more explosive? Relate the chemical composition of the volcano to the type of crust involved.
)The area we visited was originally volcanic but the rocks we saw were metamorphic.What future geological event on the east coast of the US likely provided the heatand pressure to metamorphose the rock we saw? (hint- there is a HUGE mountain range that runs up the Eastern US and even over into the UK)
Introduction to Geology Textbook
https://pubs.usgs.gov/gip/dynamic/understanding.ht…
Yellowstone Hotspot
Introduction: Review the text on hotspot volcanism and recall that hotspots produce a
string of dormant volcanoes behind an active volcano. Because we know the age of the
volcanoes and their distance from the hotspot, we can use the dormant volcanoes produced
by a hotspot to determine the speed and direction that a tectonic plate is moving. This
exercise will guide you through that process.
So, let’s think about this, if a dormant volcano is 5 million years old and is sitting 450 km
from a hotspot then it has moved 450 km in 5 million years. If we divide 450 by 5 we get
90 km/Ma. That unit is kilometers per million years (Ma is an abbreviation for millions of
years). This is not a particularly useful unit. A million years is a very long time so it’s
difficult to really understand how fast a speed given in km/Ma really is. For most of what
we do, we measure speeds in miles per hour. You know how long an hour is, and you know
how far a mile is so it’s a useful unit. For plate tectonic velocities it’s best to measure the
Speed in centimeters per year (cm/yr). Doing this gives a number usually between 1 and 15
or so which is a very useful and manageable unit. Since there are 100,000 centimeters in a
kilometer converting from km/Ma to cm/yr is relatively easy: divide by 10. So 90 km/Mais
9.0 cm/yr.
6.4 -4.3
10-7
10-7
Poca
12-10
SWAN
Yellowstone Hotspot Trace
100 km
Speed of the North American Tectonic Plate
Use the map on the previous page to figure out how fast the North American plate has
been moving since the first (oldest) volcano formed over the hotspot. The questions below
will guide you through the process. Remember to put or transfer your answers onto the
answer sheet that you will turn in. You don’t need to turn in this exercise just the answer