Reflecting on the Layers of Rock: A Study of Stratigraphy

What can we learn from the sequence of rock layers observed?

Why do we see coal near the base, followed by sandstone, then limestone, sandstone again, and finally coal near the top?

Understanding the Rock Layers

The student's question relates to stratigraphy, the study of rock layers. The sequence of coal, sandstone, limestone, sandstone, and coal signals changing environments over time - from swampy, to desert or beach-like, to marine, and back again.

This question relates to the study of stratigraphy, a branch of geology that involves the study of rock layers (strata) and layering (stratification). It involves analyzing sequences of rocks to understand the geological history of an area.

In this case, the layers from the base to top are coal, sandstone, limestone, sandstone, and coal, one on top of the other. The ordering indicates the sequence of environments in which these rocks formed. Coal usually forms in swampy environments, sandstone develops in environments like deserts or beaches, whereas the limestone forms in warm, shallow marine environments.

The pattern can suggest a fluctuation in the locality from a swampy environment to a desert or beach, then to a warm, shallow sea, then back to desert or beach and finally back to a swamp.