In very dry environments, sand can pile into large dunes. The wind causes ripples on the surface of the sand.
Fossilized ripples of windblown sand
What do fossilized dunes such as the one shown in the photo tell scientists
about the environment?
A. It was once cold and wet.
B. It used to be a glacier.
C. It used to be an ocean.
OD. It was once dry and windy.