Question

read the text. then answer the question.
mud was deposited at the bottom of a lake. over time, the lake dried up, and the area became a sandy desert.
thousands of years later, the environment became wet again. a new lake formed, and mud was deposited on top of the older sediment.
which rock sequence is more likely to form from the sediment layers described above?

Explanation:

First, mud (which forms shale) was deposited at the lake bottom. Then the lake dried up and became a sandy desert (sand forms sandstone). Later, the environment was wet again, a new lake formed, and mud (shale) was deposited on top of the older sediment. So the order from bottom to top should be shale (first - deposited mud), then sandstone (from the desert phase), then shale (new - deposited mud).

Answer:

The first rock sequence (with shale at the bottom, then sandstone, then shale on top) is the correct one.