Solutions for Concept Review/ End of Module Questions

Geologic Processes - Earthquakes, Volcanoes, & Plate Tectonics

1) In your own words, summarize the major points of the theory of plate tectonics:

The theory of plate tectonics contends that the Earth’s crust is composed of several solid plates that move around as they float on the underlying layer called the mantle. The plates move at three different types of plate boundaries (described below). The motion of the plates provides an explanation for earthquakes and volcanoes.

2) List at 5 lines of evidence that support the theory of Plate Tectonics

  1. The GPS measurements of movement of different parts of the Earth's surface (= movement of different plates)
  2. The distribution of earthquakes on the Earth's Surface
  3. The distribution of volcanoes on the Earth's Surface
  4. The distribution of mountain ranges at the edges of continents and the middle of the oceans(=mid-ocean ridges)
  5. The distribution of the same land-based fossils on continents that are separated by oceans (such as South America and Africa)

Note: you may also have found additional evidence, such as evidence of fossil showing a different climate pattern than today or evidence of glacial deposits at the equator)

3) Describe the 3 major types of plate boundaries (describe or draw the relative motion of each plate at the boundary)

  1. Divergent boundaries: Plates move away from one another.
  2. Convergent boundaries: Plates move towards one another.
  3. Transform Boundaries: Plates move sideways past one another.

4) Which types of plate boundaries are associated with volcanism?

Divergent boundaries have volcanism along the mid-ocean ridge.

Convergent boundaries where there is ocean to ocean convergence or ocean to continent convergence.

5) How do the plate boundaries off the coast of Washington state affect life in Western Washington (what geologic hazards do they produce)

Plate tectonics causes earthquakes in Western Washington and is responsible for the volcanic eruptions of the cascade volcanic arc (= Mt. St. Helens, Mt. Rainer, Mt. Baker etc.)