Answer:
only about 20% - 35%
Explanation:
We do not know that much about the earth itself, and people just recently started discovering the earth for what it truly is. Though, we have been recording earthquakes and tsunamis since the early 19th century.
This makes up anywhere from 20% to 35%. It is hard to know the exact percentage for sure.
Answer:
the oldest are on the bottom
Explanation:
work your way from the bottom to top
The answer is true.
Hope this helps.