1. if you find a rock in the hills that contains a trilobite fossil, what might that fossil tell you about the hills?
2. why do geologists believe that volcanic activity was more common in the past than it is today?

This is an answer for number one ONLY. 
Trilobite are prehistoric marine arthropods. They were sort of like crabs or spiders. The fossil was found on a hill. Hills are on land, and the trilobite lived in water. Unless left there by a previous visitor, the fossil tell that the hills were once underwater. 

Aristotle thought so every portion of the earth tends toward the center until by compression and convergence they form a sphere. travelers going south see southern constellations rise higher above the horizon.~ hope this !