One of the fundamental goals of geology is to reconstruct environments and events in the Earth's history. Many features in sedimentary and interlayered volcanic rocks record events such as mountain-building episodes, sea level changes, extinctions, and the splitting apart of continents at rifts. Stratigraphy encompasses the study of how depositional environments change in time and space, by examining the lateral and vertical variations in the rocks deposited in these environments.
Further information about tectonic settings can be derived by examining how these environments were assembled. For example, by studying sections of Devonian rocks over a large area of New York and Pennsylvania, the transitions of shallow-water limestones can be identified - demonstrating the presence of a large shallow sea in the northeastern United States 400 million years ago. The influence of a rising mountain range to the east is evident in the increasing amounts of siliciclastic sand in the younger sedimentary rocks. Careful reconstruction of the environments reveals the onset of the collision between North America and Gondwana (Africa and Europe), leading to uplift of the Appalachian Mountains.
The Stratigraphy course will be process-oriented. That is, we will address the types of depositional processes that operate in various marine and continental environments, and we will integrate the tectonic, climatic, and oceanographic processes and events that may lead to changes in the environments. Recognition criteria for many common sedimentary systems will be presented. In addition to these descriptive aspects, the course will deal with methods for analyzing "time slices" through reconstructed environments and how to track the changing environments through time.
Stratigraphic studies require a detailed record of the timing of sedimentary depositional units. A number of techniques can provide such age constraints, such as isotopic compositions of certain fossils (isotope stratigraphy), radiometric dating of interbedded volcanic units, the pattern of polarity changes recorded in magnetic minerals (magnetostratigraphy), and assemblages of fossils in the strata (biostratigraphy). These methods and others will be studied to resolve sedimentary correlation problems and to evaluate the effects of events such as change in sea level, from one location to another.
