Where, I'm unsure, but when, I think I know. There is a theory that the first asteroid to hit Earth was actually a comet. It wiped out the dinosaurs.
Answer:
4 billion years
Explanation:
Scientists have found the oldest known rocks on Earth. They are 4.28 billion years old, making them 250 million years more ancient than any previously discovered rocks. Earth formed about 4.6 billion years ago from a disk of gas and dust circling the sun.
Answer:A. Marine West Coast
Explanation:
Answer:
It is difficult to cross.
Explanation:
The Sahara desert is a vast region about the size of the continental United States that is extremely dry and barren. The lack of water resources in the desert make the land unsuitable for agriculture and human population.
As a result, the Sahara acts as a giant natural wall both economically, culturally, and socially since relations between states to the north and south of the desert are difficult.
