Correct
Answer(s):
E
7.
What sort of rock is pictured above?
A)
Marmot #2
B)
Sediment that isn’t rock yet. The layers are alternating silt and sand from deposition from landslides off the
Olympic Peninsula into the trench offshore.
C)
Metamorphic; The rock separated into layers as it was cooked and squeezed deep in a mountain range.
D)
Sedimentary; The layering was caused by changes in the flow velocity of the river that deposited the
material
E)
Igneous; The layers were caused by flow processes during the eruption that released this.
Feedback:
The large crystals, intergrown nature, and separate dark and light layers all point to metamorphism,
deep inside a mountain range. Rapid cooling in volcanic eruptions gives tiny crystals, not the big, pretty ones here.
You can see the former sand grains or other-sized pieces in sediment and sedimentary rocks. And marmot doo-doo
consists of small, dark pellets, akin to big rabbit doots, and usually isn’t considered to be rock.
Points Earned:
1.0/1.
0
Correct
Answer(s):
C
8.
A 100-foot-high tsunami wave nearly kills you in your boat. It is likely that:
A)
Your boat was in shallow water near the shore, because tsunami waves are usually long and low out in the
deep water of the central ocean, but pile up to become high when slowed by the friction in shallow water near the
shore.
B)
You cannot tell where you were, because tsunami waves never affect boats.
C)
Your boat was in deep water far from shore, because tsunami waves are usually very high when formed out
in the ocean but get shorter when damped by the friction in shallow water near the shore.
D)
The question must contain wrong information, because tsunami waves are always long and low and so
could not have been 100 feet high.
E)
You cannot tell where you were, because tsunami waves are usually very high out in the open ocean and
remain high when nearing the shore.
Points Earned:
1.0/1.
0
Correct
Answer(s):
A
9.
Tsunamis:
A)
Are like the seasons; they can be predicted accurately months in advance, allowing wise planning.
B)
Are completely unpredictable on all time scales.
C)
Always are huge and destructive.
D)
Are like the weather; they can be predicted fairly accurately days in advance, allowing wise planning.
E)
Are like tornadoes; they can be predicted with some accuracy seconds to hours before they strike in most
cases, allowing quick warnings to save many lives.
Feedback:
Because tsunamis are triggered by earthquakes, among other things, and we cannot predict
earthquakes accurately, we cannot make months-in-advance predictions of tsunamis. The p-waves from the
earthquakes that cause the most common tsunamis move much more rapidly than the tsunamis do, allowing timely
warnings; however, because the tsunamis get where they are going in hours or less typically, not much time is
available. Water does go out before rushing in along some coasts, but comes in before going out along other coasts,
waves have “up” and “down” parts, and some coasts get an “up” first while other coasts get a “down” first. Little
earthquakes make little tsunamis; big earthquakes make big tsunamis.
