Two forces, resulting from plate tectonics, are tension V pulling the crust apart or pushing up on it from below V and compression V squeezing the crust from either side. The sediments are accumulated, often on the ocean floor but also in situations such as sand dunes, in horizontal layers. When buried deep, the compression and cementation create horizontal layers or strata. The tilt of such strata reveal process of earth dynamics. A splitting and offset of strata reveals faulting.
Normal faults occur when there is relative movement down the dip of the fault due to tension.
Reverse faults occur when the relative movement is up the dip, and results from compression. Overthrust faults start as reverse faults, but the crust breaks and a large section is carried over on top of the strata that had been at the same level. This is what has occurred in the Great Basin of the western US where we see fault-block mountains and valleys. Folding and metamorphic rock Folding is caused by slow compression and the rock responds by bending. Metamorphic rocks are the result of high pressure and heat V enough the change the crystal structure of the rock by changing positions of the atoms V but not enough for it to become molten.