The fine particles that compose shale can remain suspended in water long after the larger and denser particles of sand have deposited out. Shales are typically deposited in very slow moving water and are often found in lake and lagoonal deposits, in river deltas, on floodplains, and offshore of beach sands.
[image] Fossils, animal tracks/burrows, and even raindrop impact craters are sometimes preserved on shale bedding surfaces. Shales may also contain concretions.
Shales that are subject to heat and pressure alter into a hard, fissile, and metamorphic material known as Slate that is often used in building construction.