Stratigraphy

Stratigraphy is the study of rock and sediment layers—their composition, sequence, and the stories they tell about Earth's past. By reading these geological pages, scientists reconstruct ancient environments, track the passage of time, and understand how our planet has transformed.

The discipline rests on a simple but powerful principle: younger layers sit atop older ones (the Law of Superposition). Geologists examine the thickness, color, texture, and fossil content of each stratum to interpret what happened when—whether a region was once a shallow sea, a river delta, or a desert.

Stratigraphy is essential to paleontologists hunting for ancient extinctions and evolutionary milestones, to archaeologists dating human settlements, and to those tracking the human epoch. It also reveals practical truths: where to find water, fossil fuels, and mineral deposits.

The discipline blends observation, chemistry, and imagination. A thin ash layer might mark a single volcanic eruption; a sequence of ripples suggests tidal action; color shifts hint at climate change. Every stripe in a cliff face is a page in Earth's autobiography, waiting to be deciphered.

Related

Paleontology, Geology, Fossils, Sedimentology, Absolute dating, Relative dating