Foliation

Foliation is a geological term describing the layered or banded appearance seen in some rocks, especially metamorphic rocks. It occurs when mineral grains within the rock are aligned or segregated due to intense pressure and heat during geological processes. These aligned layers can be thin and sheet-like, reflecting the stress direction the rock experienced. Foliation helps geologists understand the history and formation conditions of rocks, acting like a record of the geological forces that altered them. It is a key feature in identifying and classifying metamorphic rocks.