GEO 103 Lecture 12: Deltas and Evolution
26 Feb 2017
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Document Summary
Transitional environments are those with both marine and continental processes. Where river enters sea to form delta - deposits modified by marine processes such as waves and tides. In ascending order: bottomset, foreset, and topset beds. Coarsens upward as delta builds outward (progrades) into water body). Aka it coarsens near the top of the delta. 3 major types of deltas reflecting dominant processes: A majority of the sediment is controlled by the river. The waves build a beach along the river delta which keeps the sediment in a controlled area. This leads to sediments being kept in, but unlike waves, it does not form beaches but mud flats. On sandy continental margins long barrier islands form, separated from shore by lagoon. Unlike desert sands, these contain marine fossils which indicate that they are beaches. Dune sands with shell fragments not from desert. These dunes are important to oil companies since they can hold resavoirs of oil.
