Midterm Review

Which statement best supports the theory of continental drift?

• Basaltic rock is found to be progressively younger at increasing distances from the mid-ocean ridge.
• Marine fossils are often found in deep-well drill cores.
• The present continents appear to fit together as pieces of a larger landmass.
• Areas of shallow-water seas tend to accumulate sediment, which gradual sinks.

The edges of most lithospheric plates are characterized by

•  reversed magnetic orientation
• unusually rapid radioactive decay
• frequent volcanic activity
•  low P-wave and high S-wave velocity

Which statement correctly compares seismic P-waves with seismic S-waves?

• P-waves travel faster than S-waves and pass through Earth’s liquid zones.
• P-waves travel faster than S-waves and do not pass through Earth’s liquid zones.
• P-waves travel slower than S-waves and pass through Earth’s liquid zones.
•  P-waves travel slower than S-waves and do not pass through Earth’s liquid zones.

The movement of tectonic plates is inferred by many scientists to be driven by

• tidal motions in the hydrosphere
• density differences in the troposphere
• convection currents in the asthenosphere
• solidification in the lithosphere

A seismic P-wave is recorded at 2:25 p.m. at a seismic station located 7600 kilometers from the epicenter of an earthquake. At what time did the earthquake occur?

• 2:05 p.m.
• 2:11 p.m.
• 2:14 p.m.
• 2:36 p.m.

How long after receiving the first P-wave from an earthquake centered 4000 kilometers away does a seismic station receive its first S-wave from the same earthquake?

• 1 minute
• 5 minutes 35 seconds
• 7 minutes
• 12 minutes 40 seconds

Which evidence supports the theory of seafloor spreading?

• The rocks of the ocean floor and the continents have similar origins. 
• In the ocean floor, rocks near the mid-ocean ridge are cooler than rocks near the continents. 
• The pattern of magnetic orientation of rocks is similar on both sides of the mid-ocean ridge. 
• The density of oceanic crust is greater than the density of continental crust.

According to the graph of P-wave and S-wave Travel Times in the reference information, which generalization about earthquake S-waves and P-waves is correct?

• When the P-waves and S-waves are near the epicenter, they both travel at the same speed.
• The velocity of P-waves and S-waves is constant, regardless of the distance traveled.
• P-waves always travel faster than S-waves, regardless of the distance traveled.
• S-waves always travel about twice as fast a P-waves.

In Earth’s interior, which zone has a temperature higher than its melting point?

• crust 
• stiffer mantle 
• inner core 
• outer core

Hot springs on the ocean floor near the mid-ocean ridges provide evidence that

• convection currents exist in the asthenosphere 
• meteor craters are found beneath the oceans 
• climate change has melted huge glaciers 
• marine fossils have been uplifted to high elevations