Science/Geology Question ?

Tension between rock layers builds up until it releases in the form of energy (earthquakes). Shear force moves one crustal block along another, sidewise. It also causes deformation at the surface. Compression shortens and thickens rock layers in the direction of compression and elongates them perpendicular to the direction of compression. Compression is the most likely to form mountains, but there can be a shear component as well.