geological layers

Geological layers are the distinct horizontal strata of rock, sediment, or soil that accumulate over time, each representing a different period of Earth's history.

Geologists read these layers like pages in a book—older deposits lie beneath younger ones, preserving fossils and evidence of ancient environments.

The geological layers in the canyon walls span millions of years.

The term applies both to actual rock formations and to the scientific concept of stratigraphic analysis.