An oceanographer is traveling from the west toward the east on the Atlantic Ocean. She collects rock samples from the seafloor every 5 kilometers. The oceanographer stops when she determines that the rock samples are getting progressively younger as she moves toward the east. What conclusion is best supported by this data?
A. She is traveling toward a mid ocean ridge.
B. She is traveling toward a deep ocean trench.
C. She is traveling away from an underwater volcano.
D. She is traveling away from a hot spot in the crust.
Geologists installed tilt meters in a tectonically active area. Tilt meters can detect very small changes in the slope (tilt) of Earths surface. These changes result from the upward movement of magma beneath Earths surface. What event could be predicted by monitoring these changes?
A. a potential volcanic eruption
B. reversal of Earths magnetic field
C. a change in the composition of Earths crust
D. decreased thermal energy transfer within Earth
What evidence has been used to support the theory of plate tectonics?
A. The Grand Canyon runs in the same direction as the mid-Atlantic ridge.
B. There are deserts in the western parts of North and South America.
C. The same fossil species are found in South America and Africa.
D. Glacial till covers parts of the northern United States and Asia.
Answers & Comments
Verified answer
(1) -- (A) Crust is created at the Mid-Ocean Ridge network, so as you move toward it, it becomes progressively younger. Trenches are very old crust, and the two volcano things have nothing to do with aging the seafloor save very locally, or if you count the MOR as a volcano (which it is, technically). In which case it would still be wrong, as you're moving away (or *she* is moving away).
(2) -- (A) As magma rises, it pushes rock out of the way, causing the ground to deform to accommodate the new material. We know that two pieces of matter can't occupy the same space at the same time. Look at the bulge on Mount St. Helens before it erupted, that was a perfect example. The other three are just... really wrong.
(3) -- (C) Fossil distribution on either side of the Atlantic. Wegener found exact copies of rock and fossil sequences on each side of the ocean. The statistical probability of that happening that perfectly is zero. That implies that somehow, those two continents were a single continent that broke and moved apart. The Grand Canyon was formed by a river, deserts can happen wherever there's a lack of precipitation, and glacial till covers parts of North America and Asia because during the ice ages, there were a lot of... glaciers and other ice sheet.