A single layer or bed of sedimentary rock, usually one of a series of layers that have been deposited one on
top of another. Each stratum indicates the conditions that prevailed at
the time of its deposition. The study of strata is called stratigraphy.
The stratigraphical or geological column contains all the periods of geological
time. Rock strata may be very thin, of just a few centimeters thickness, or they may
be several meters in extent. Initially, they are usually horizontal, but
they are likely to be affected by folding and faulting. Separations between
individual layers are called stratification planes.
|Rock strata near Depot Beach, New
Photo credit: D. M. Vernon / Wikipedia
The law of superposition in geology states that in undisturbed layers of sedimentary rock, younger strata overlie older ones.
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