Stratigraphy

Stratigraphy is the science of interpreting and describing layers and strata of sediments. Commonly these layers are levels of sedimentary rock, but stratigraphy can also include the study of non-ossified sediments, like those in stream beds and lake bottoms, of inclusions such as volcanic ash and lava, and even the study of different layers of human occupation. Sediment usually forms distinct strata with the most recent layers on top and, although they may be folded by continental drift, interrupted by inclusions and slippages, and even metamorphosized into other forms of rock, as long as these strata can be untangled and interpreted, scientists can perform stratigraphic analyses. The processes of sedimentation—including the presence of certain types of fossils—provide scientists with valuable clues about the age of the earth and its history. These principles are thus valuable for many different types of scientist, ranging from prospecting geologists to city planners to archaeologists and paleontologists studying human and animal history and prehistory.