What explanations can you give for why some people are rich and some people port?

What's erosion? a. the breakdown of rock into smaller pieces b. the removal of weathered products from rock c. a change in rock resulting from exposure to water d. a chemical change in rock that weakens it

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

In the following diagram, four different index fossils are labeled: which of the labeled fossils comes from the oldest organism? a b c d