Question

A limestone bed containing fossils that are 550 million years old is ____ a bed of sandstone containing fossils that are 400 million years old.
a. younger than
c. older than
b. the same age as
d. not related to

Answer 1

Limestone is a sedimentary rock composed primarily of skeletal fragments of marine organisms. The presence of fossils reveals the biological origin of these rocks.

A limestone bed containing fossils that are 550 million years old is older than a bed of sandstone containing fossils that are 400 million years old.

Answer 2

So we have two limestone beds, one of 550 million years old (well, the fossils are, but it suggests that the rock was created around the same area) and another that is 400 million years old. The first one is then older than the second - the correct answer is c!