Index fossils are found a. in a very small geographic area.

b. in igneous rocks.

c. widely scattered in rocks over a large region.

d. widely scattered through many layers of rocks.

Relatively steep zone that is compared with the shelf that marks the boundary between continental crust and ocean crust.

One of the main reasons societies settled along rivers in the neolithic era was because a) the village elders demanded it. b) the land there was more valuable. c) it was more safe and secure there. d) it provided irrigation for farming.

17. the soil erosion pictured here is the result of what? a. harvesting renewable resources at a rate greater than the sustainable yield b. a mudslide caused by excessive rains c. harvesting renewable resources at a rate lower than the sustainable yield d. the transition between geologic eras and eons