Continuous Change of Earth’s Surface Synthesis ExerciseThe central image in the following...

Continuous Change of Earth’s Surface Synthesis Exercise

The central image in the following figure shows a hypothetical plate configuration. Assume that research has revealed that the three pieces of continental crust are moving at different speeds, directions, or both. Plate A is traveling at 5 centimeters per year (50 kilometers per million years), B is also moving at 5 centimeters per year, and C is traveling west at 2 centimeters per year (20 kilometers per million years). The directions of A and B should be apparent from the plate configuration. Answer the questions that follow.

1. How many plates are present in the central figure?

---

2. Sketch and label a cross section through the lithosphere along the line X–Y in the central figure.

---

3. Fill in the upper and lower templates to show what the plate configuration looked like 4 million years earlier and what the plates will look like 15 million years in the future. Draw the configurations relative to the oceanic ridge (that is, assume it stays in the same place and everything else moves).