Why is the valley V-shaped in the upper course?

What evidence does the writer give to support his argument about coral reefs? a) he speaks of the activities of coral polyps. b) he describes the composition of the great barrier reef. c) he emphasizes the ways in which coral reefs are fragile. d) he points out the ways that scientists do research on the reefs.

How did geographic isolation affect the islands in the australasia ecozobne?

What could the united states of america do to improve their status? name at least 3(ap human geography)