Answer:
a) are the sources of long-period comets.
Answer:
True
Explanation:
because of its longer term and smaller size
Fossils help scientists date rocks: True
Sometimes younger rock layers are found beneath older rock layers: True, because it happens with landslides and other causes.
No fossils from the Precambrian era have been found because there were no organisms at the time: False because there were organisims like algae and bacteria, and there are a very small amout of fossils from that era.
The map of Earth has changed over millions of years, but is now set: False
They thought that it might keep them safe from harm.
