effective grain size的意思|示意

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Effective grain size, or \\"mean grain size,\\" is a term used in geology to describe the size of the individual grains in a sedimentary deposit. It is important to geologists because it can reveal information about the environment in which the deposit formed, because it can tell us about the energy available to move and sort the sediments.

In general, grain size will decrease as the amount of energy in the environment increases. For example, if the sedimentary deposit is in a fast-moving river, it will have a smaller grain size than a deposit in a slow-moving river due to the increased energy available for sorting and abrading the grains. Likewise, if a sand deposit is in the ocean, the grain size will be much smaller than if it is onshore, due to the greater energy present in the ocean environment.

The effective grain size can be determined by measuring the average grain diameter using a microscope. It is important to note that this type of measurement is only applicable to deposits of clastic sediments, such as sand, silt and clay.

Grain size can also be used to help determine the age of the deposit. As the grains in the sedimentary deposit become more rounded, they become easier to move and can be transported farther distances. This means that a sedimentary deposit that has been exposed to a high-energy environment for a longer period of time will usually have a smaller average grain size than a recently-deposited deposit.

Overall, effective grain size is an important indicator that can help geologists understand the environment in which a sedimentary deposit formed and the age of the deposit. It is an important factor to consider when studying deposits, and is an important aspect in the study of geology.