Physical classification of rocks is based on general structure of rocks. According to this classification, the rocks can be of three types.

STRATIFIED ROCKS:

Stratified rocks show a layered structure in their natural environment. They possess planes of stratification or cleavage and can be easily split up along those planes. Sedimentary rocks are distinctly stratified rocks, eg; sandstone, limestone, slate, etc.

UNSTRATIFIED ROCKS:

 The rocks which do not show any sign of strata and cannot be easily split into thin layers are called unstratified rocks. Their structure may be crystalline or granular. Granite, trap and marble are the common examples of unstratified rocks.

FOLIATED ROCKS:

These rocks have a tendency to split up in a definite direction only. The foliated structure is very common in case of metamorphic rocks