Wednesday, July 1, 2015
Stratigraphy is that branch of geology that studies the layers of rocks. The strata are the different layers of rocks, here easily seen as different colors and types of rocks. Layering or stratification primarily occurs in sedimentary or volcanic rocks. A cross-section is a view of the rocks revealing a vertical profile. Geologists, or more specifically stratigraphers, study the deposition history of the rocks and try to reconstruct how and when the rocks were deposited. They rely on the law of superposition, that non-deformed geologic strata are deposited in a sequence where the older material is deposited on the bottom of the sequence and the the younger material on top. They also assume that the rocks were originally deposited horizontally aka the principle of original horizontality.