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.

In the water cycle , when does water undergo a chemical change

Which statement correctly describes other ways in which nebulae and stars are different? a. a star always has a higher density than a nebula. b. stars can form inside a nebula but a nebula can never be produced by any star. c. stars can never form inside a nebula but a nebula can be produced by any star. d. a nebula always has a higher density than a star. reset submit

When energy is used, atp molecules convert to adp molecules. this process is called