Pisgah Field Trip

The following is your field trip pre-trip assignment. Complete questions 1 through 5. Use a
separate sheet of paper. If you need to use a geological dictionary for some words, there
is one in the library. This assignment should take you 1 hour or more so don’t wait until the
morning of the trip to start. Read the second set of questions so you will know what to look
for during the field trip.

1. During the week before the trip, you will need to check out a hard hat. You can not
enter the lava tubes without one! Be sure to share your hard hat with your classmates
since we don’t have enough for everyone. Also, it is totally dark in the tube so be
sure you bring a working flashlight, the larger the better.
2. Read/reread the section in a text on volcanoes and magma types; write the page
numbers here for what you have read: ____________________________________.
3. Define the following words. We should use all of the following vocabulary on the
trip; if not then ask:

3.1. aa (also spelled a’a)
3.2. aggregate
3.3. alluvium
3.4. basalt
3.5. contact metamorphism
3.6. desert pavement
3.7. entrail pahoehoe
3.8. fault
3.9. fire fountain
3.10. fissure
3.11. hectorite
3.12. Holocene
3.13. Ice Age climate of the Mojave Desert
3.14. lava tube
3.15. levee
3.16. pahoehoe
3.17. playa
3.18. Pleistocene
3.19. principle of superposition
3.20. pyroclastic cone a.k.a cinder cone or tephra cone
3.21. shelly pahoehoe
3.22. squeeze up
3.23. vent
4. Explain how a simple lava tube may form.
5. Compare the Udden Wentworth sediment size scale to sizes of pyroclastic
material. The best ways to do this is in a table or list them side by side.

During the trip: you will need to take data to use in answering the write up questions on the
other side of this sheet. Read the questions before we leave and ask about parts that you do
not understand before the trip!

Following are the questions to be completed on the field trip and written up afterwards.
Type all answers, put them in the order given, include your pre-trip at the end, and
place it all in a three-hole paper folder. You will need to neatly
redraw any required sketches and place them in the proper location:

1. Submit a diary of all stops and events of the day. Include non geological events
as well as your scientific observations. (50 points; note that this question
is competitive and the most complete answer will get all 50 points.)
2. Sketch and label the inside of the pyroclastic cone. What evidence suggests that
lava flowed into the lower part of the crater? What evidence suggests that the lava did
not flow out of the cone? (10 points)
3. Describe what a fire fountain would look like. Then explain how it could produce
lava flows; be sure to indicate the general viscosity of the lava emitted. (10 points)
4. Looking out toward the south, you see a ridge on the east and lava flows
stretching toward the west. This ridge formed by the build up of lava emitted during
a fire fountain event at the fissure. Describe or sketch and label the difference in
appearance between the aa flows and the pahoehoe flows. (10 points)
5. Sketch and label the lava levees at the north end of the fissure. Note that they
continue under the debris that forms the path and under Pisgah Cone. (10 points)
6. Before going down to the lava tubes, sketch the natural outer surface of Pisgah
Cone. The area near the lava levees is a good place to look at this material. (5 points)
7. Describe the inside of the lava tubes. Please be more specific than “dark and
dusty.” (10 points)
(10 points)
9. During the walk on the way back to the bus, observe the texture and fusing of
the volcanic material exposed by the mining operation. Explain how this material
is different than the material sketched in question number 6. (5 points)
10. The hectorite formed during contact metamorphism of lake sediments. How did
that happen? What Holocene landform occupies the site of the Pleistocene lake?
(10 points)
11. What was mined at Pisgah Cone? Give the two major uses for this material. Hint:
it wasn’t hectorite. (10 points)
12. When we stop to look at the desert pavement, sketch and label Pisgah Cone showing
its relationship to Pisgah’s lava flows. Using the principle of superposition, which is
younger? (10 points)
13. Explain the formation of the Pisgah Field, which includes the cone, fissure, and
lava flows. Be sure to indicate the relative ages, not years, using the principle of
superposition. You will need to consider changes in viscosity over time to explain
how this eruption changed over the few years that it was active. This is your think
question so don’t waste time looking for the answer in the book or on the Net. (30 points)
14. Pre-trip assignment with initials. (20 points)

Pisgah

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