Chalk in Cyprus, showing sedimentary layering. The clear layers are probably caused by changes in climate, as with rhythmites.

Crumpled mudstone strata, Ceibwr Bay, Cardigan Bay, Wales.

A rare fold in the rock strata, a change from the mainly large, flat slate layers on the headland here. Boscastle, Cornwall

Stratigraphy is a branch of geology which studies rock formations called strata (layers). It is important in the study of sedimentary and layered vocanic rocks.