Like a pane of glass dropped on the floor, some rocks are brittle: They break, or fracture, in response to stress. Rocks tend to fracture when stress is applied rapidly, at shallow depths, or at low temperatures. If rocks on each side of a fracture are displaced, the fracture becomes a fault. Earthquakes result from the brittle deformation that also creates faults.

		Slickensides The shiny surface on this slickensides was polished by fault movements.
		Limestone Movement in a fault zone chopped this layered limestone into pieces, which tilted like books on a shelf.
		Sandstone After pore water was driven out of this sandstone, it took up less space. More than 24 faults accommodated the loss in volume.