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Placer deposit. Heavy minerals (black) forming placers along ripple marks. In geology, a placer deposit or placer is an accumulation of valuable minerals formed by gravity separation from a specific source rock during sedimentary processes. [1] The name is from the Spanish word placer, meaning " alluvial sand".
Placer mining. 19th-century miner pouring water into a rocker box which, when rocked back and forth, will help separate gold dust from the alluvium. Placer mining (/ ˈplæsər /) [1] is the mining of stream bed deposits for minerals. [2] This may be done by open-pit mining or by various surface excavating equipment or tunneling equipment.
Eluvium. In geology, eluvium or eluvial deposits are geological deposits and soils that are derived by in situ weathering or weathering plus gravitational movement or accumulation. The process of removal of materials from geological or soil horizons is called eluviation or leaching. There is a difference in the usage of this term in geology and ...
An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but are also found in more humid environments subject to intense rainfall and in areas of modern glaciation.
Soil formation, also known as pedogenesis, is the process of soil genesis as regulated by the effects of place, environment, and history. Biogeochemical processes act to both create and destroy order ( anisotropy ) within soils.
The Wilcox Group is an important geologic group in the Gulf of Mexico Basin and surrounding onshore areas from Mexico and Texas to Louisiana and Alabama. The group ranges in age from Paleocene to Eocene and is in Texas subdivided into the Calvert Bluff, Simsboro and Hooper Formations, [1] and in Alabama into the Nanafalia and Hatchetigbee ...
Term. Podzol means "under-ash" and is derived from the Russian под (pod) + зола́ (zola); the full form is подзо́листая по́чва (podzolistaya pochva), meaning "under-ashed soil". The term was first given in mid-1875 by Vasily Dokuchaev. [3][4] It refers to the common experience of Russian peasants of plowing up an ...
Placer (Portuguese: parcel or pracel) is a term used by Portuguese and Spanish navigators and cartographers to refer to a certain kind of submerged bank or reef. Commonly the bottom of such a reef is sandy, but there are some where the bottom is muddy or stoney. Although most reefs designated as placer are flat and shallow, exceptionally there ...