Earth's Interior and Plate Tectonics

Which best describes the shape of Earth's inner core?

• tetrahedral

• cylindrical

• spherical

• elliptical

Alfred Wegener’s 1915 hypothesis of continental drift was backed by abundant evidence. For example, cartographers throughout history noticed the

• ocean plates look like they fit together.

• mountain chains between continents are similar.

• continents look like they fit together.

• sizes of South America and Africa are the same.

Which of the following best explains the difference between continental drift and plate tectonics?

• Continental drift describes the motion of Earth's continents only; plate tectonics describes the motion of the crust beneath Earth's oceans as well.

• Plate tectonics was Wegener's theory that Earth's continents rest on sections of Earth's crust that drift together and apart over time; continental drift is a hypothesis describing how plate tectonics might happen.

• Continental drift was Wegener's hypothesis that Earth's continents were once part of a supercontinent that has since broken apart; plate tectonics is the theory that explains how continental drift happens.

• Continental drift is supported only by observations of similar coastlines and geologic features on opposite sides of an ocean; plate tectonics is supported by a wide range of fossil evidence as well.

Which statement best explains how the continents have changed over the last 200 million years, according to the continental drift hypothesis?

• They drifted into and out of about fifteen different supercontinent configurations.

• They formed a stable supercontinent until the last ice age, when they rapidly moved to their current positions.

• They split apart from a supercontinent and very slowly moved to their current positions.

• They drifted into and out of about seven different supercontinent configurations.

A student concludes that Earth's lithosphere is gradually shrinking as crust is destroyed at subduction zones. What is wrong with this conclusion?

• Earth's lithosphere is actually growing because much more crust is being created at subduction zones than destroyed.

• Earth's lithosphere is not shrinking because new crust is being created at mid-ocean ridges.

• The student is correct; Earth's lithosphere is shrinking.

• Earth's lithosphere is not shrinking because crust is not actually destroyed at subduction zones; it simply sinks into the mantle before resurfacing elsewhere.

Which is the correct order of Earth's structural layers, from top to bottom?

• lithosphere, asthenosphere, mesosphere, outer core, inner core

• outer core, inner core, mesosphere, asthenosphere, lithosphere

• asthenosphere, mesosphere, lithosphere, outer core, inner core

• outer core, inner core, lithosphere, mesosphere, asthenosphere

Why do scientists divide Earth's core into an outer core and an inner core?

• They were formed in different geologic eras.

• They are divided by a layer of partly molten material called the mesosphere.

• They exist in different states of matter.

• They have a different chemical composition.

Which statement best describes Earth's core?

• The outer core is solid and the inner core is liquid.

• The outer core is partly molten and the inner core is fully molten.

• The entire core is solid.

• The outer core is liquid and the inner core is solid.

Deep sea trenches are associated with which of the following?

• subduction zones

• rift valleys

• fault-block mountains

• transform boundaries

Which evidence supports Wegener's continental drift hypothesis?

• the buildup of sediment along continental margins

• meteorite impact craters in continental crust

• similar fossils found on opposite sides of an ocean