Geology Midterm 2
What is a principle we use to determine the age of a landscape surface?
a surface with a well-developed soil is probably older than a surface with no soil
What was the Cambrian explosion?
a time when many different types of creatures appeared on Earth
What is a popular model for the formation of an atoll?
a volcanic island forms and subsides
In the Atlantic Ocean, where is the oldest oceanic crust?
abyssal plain next to the continents
If an area has shallow, intermediate, and deep earthquakes, what can you infer about the area?
all of the above
In this photograph, Paleozoic sandstone rests depositionally on Precambrian granite. What events must have occurred before deposition of the sandstone?
all of the above
Shaking during an earthquake can:
all of the above
What are some uses of magnetic reversals?
all of the above
What are the geologic features for which Siccar Point in Scotland is famous?
all of the above
What would fossil ages from the geologic timescale tell us about the age of this unconformity?
all of the above
Which of the following is evidence that Earth's history is not short?
all of the above
What could cause a region to be higher in elevation than an average part of a continent?
b. less dense continental crust
If you were looking for graded beds, where would be a good place to start?
in a submarine fan
What has happened to the Pacific Ocean in the last 200 million years?
it became smaller as the Atlantic Ocean opened
What is the main reason why the age of oldest rocks can vary from one part of a continent to another?
parts of the continent have been added by the accretion of tectonic terranes
How do we determine the location of a recent earthquake?
use seismic records from three or more stations
The basin shown in this figure was actively subsiding during the formation of unit:
C
What causes the seafloor to deepen across a typical continental slope?
a and b only
What processes can occur in front of or behind some island arcs?
a and b only
If a rock started with 1,000 atoms of a parent but now contains 250 atoms, how many half lives have passed?
2 half lives
Which of the following is NOT a way in which local mountains can be built?
all of the above are ways to make local mountains
Why are the patterns showing the age of the seafloor symmetrical in the Atlantic Ocean but not the Pacific Ocean?
both a and b
The characteristics of S-waves include:
both b and c
How can we tell that the Himalaya have been uplifted?
d. all of the above
Which of the following occurs when mountain belts are eroded?
d. all of the above
Which of the following processes forms basins in an ocean-continent convergent boundary?
e. a and b only
What can occur during the evolution of a hot spot?
formation of rifts that radiate out from the hot spot
If you drilled into an oceanic plateau, what would you most likely find?
large amounts of basalt derived from melting in the mantle
Which of the following processes generates most earthquakes?
movement along faults
Areas of high earthquake risk are mostly located:
near a boundary between tectonic plates
What is one way that we determine the depth to the base of the crust?
observing whether seismic waves that travel through the crust arrived after those that traveled through the mantle
Seafloor spreading rates cannot be used to reconstruct past continents' positions older than 180 million years. Why?
oceanic crust older than 180 million years has been subducted and the record destroyed
Which of the following is NOT a setting in which regional mountain belts form?
passive margin
When do rocks along a fault have the highest amount of stress and stored elastic strain?
right before an earthquake
Sudden movement on a fault can cause a tsunami when:
the fault suddenly uplifts or downdrops the seafloor
This figure shows two sections that partially overlap in age. Dashed lines show how the two sections correlate. What can you conclude from these correlations?
the left section represents older rocks than the right section
This figure shows two fault scarps, a lava flow, and erosion along one of the scarps. What is probably the oldest feature of those listed below?
the scarp on the right
How do most oceanic islands and seamounts form?
they are constructed by volcanic eruptions that first occur under water
The huge 1964 Alaskan earthquake, one of the largest earthquakes ever recorded, was caused by:
thrusting along a subduction zone (megathrust)
What factors are the most critical in determining whether a fossil is preserved?
whether the creature had hard parts and how fast it was buried
