Question

The sedimentary rock that forms when water deposits particles of clay in thin layers is called what?

Answer 1

Shale.

Explanation:

Shale generally contains not just clay but a variety of materials. That includes organic matter which could serve as a (fossil) fuel source. See https://en.wikipedia.org/wiki/Shale. These are the source of the controversial "fracking shales" that contain both oil and natural gas, but cause a number of environmental impacts.

Shales often contain the remains of well preserved fossils, such as those found in the Burgess Shales of B.C. Canada.