Three ways that humans affect earths systems

In 1915 the german geologist and meteorologist alfred wegener first proposed the theory of continental drift, which states that parts of the earth's crust slowly drift atop a liquid core. the fossil record supports and gives credibility to the theories of continental drift and plate tectonics.

If scientists only detect p waves in a certain layer of earths interior what does that tell us?

In a class of 20 students, what democratic form of governance makes the most sense