Name ____________________
Regional Field Geology Mt. St. Helens
Quiz Follow-up
Please read the Mt. St. Helens (MSH) chapters and answer the following questions (type
answers). Due April 5 class.
1. What was the date and time of the cataclysmic1980 Mount St. Helens eruption?
2. How old is Mt. St. Helens?
3. Make a sketch that shows a simple outline of the profile of the volcano before and after the
eruption. Describe how MSH landscape changed due to the 1980 eruption.
4. Describe the basic sequence of the eruption. From the triggering event to the big eruption.
Did the eruption have different phases, if so, describe them.
5. There were several different kinds of pyroclastic density currents associated with the 9 hour
eruption. Describe as many as you can.
6. Volcanologists learned a lot about volcanoes and volcanic hazards from the 1980 eruption.
Describe, in as much detail as possible, two different lessons that were learned.
7. Describe the major geologic events that have occurred at MSH in the three decades since the
1980 eruption.
8. There are several different volcaniclastic rock units at MSH. For each of the units listed below,
try to describe the distinguishing features of the unit. The reading will be helpful but will not be
as complete, so use (and cite) other sources.
a. Lahar deposits
b. Pyroclastic Flow deposits
c. Pyroclastic Surge deposits
d. Pyroclastic Fall deposits
9.
a. How would you differentiate a glacial till, pyroclastic flow, and lahar deposits?