sedimentaryII

sedimentaryII - Physical Geology 101 14. Sedimentary Rocks...

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Physical Geology 101 1 14. Sedimentary Rocks II (p. 208-217) Depositional Environments Sedimentary rocks can tell us a lot about the type of environment in which they formed, such as a river, a beach, or a glacial environment, and the past distributions of such environments. These types of studies of sedimentary depositional environments form a sub-discipline of geology called: ________________________. Sedimentary Structures Sedimentary structures provide clues about the type of depositional environment a particular sedimentary rock formed in. Sedimentary structures are the ________________________________________ that form during or after deposition as a result of physical or biological processes in the depositional environment. In other words, they are generally some form of observable characteristic of the rock appearance , EXCLUDING rock color or the type of sediment present. Types of structures : 1) Layers within sedimentary rocks form a type of sedimentary structure called: __________________ (or stratification) How thick are beds? _________________________ Beds represent a more or less continuous episode of deposition of sediment. They are separated by flat surfaces called ________________________ along which the rock tends to part or break. Bedding planes represent one of the following two possibilities: (1) ___________________________________________________________ (2) ___________________________________________________________ At some later time after a bed has formed, a new layer of sediment is deposited on top of it, forming a new bed. 2) Sometimes we can see gradual changes in the size of sediment grains from the bottom to the top of an individual bed. This is a type of sedimentary structure called: _______________________________ What size sediment is at the bottom of a graded bed? ____________ or ____________ What size sediment is at the top of a graded bed? ____________ The reason this happens is because of a gravitational effect in flowing water. The larger, heavier clasts are hard for the water to carry, so they are the first to sink to the bottom when the water slows down and
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Physical Geology 101 2 loses energy. As the speed of the water decreases, progressively smaller clasts settle down on top of the
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sedimentaryII - Physical Geology 101 14. Sedimentary Rocks...

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