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Wave or channel erosion of the edge of the fan (lateral erosion) sometimes produces a "toe-trimmed" fan, in which the edge of the fan is marked by a small escarpment. [9] Toe-trimmed fans may record climate changes or tectonic processes, and the process of lateral erosion may enhance the aquifer or petroleum reservoir potential of the fan. [ 10 ]
The thickness of alluvial fans forming due to basin margins are influenced tectonically. [3] If the alluvial fan gets thicker and the grains become more coarse heading up the fan, this indicates that the basin margin is tectonically active and the building of the alluvial fan being more active than the deposition rate.
Matrix-supported conglomerates, as a result of debris-flow deposition, are quite commonly associated with many alluvial fans. When such conglomerates accumulate within an alluvial fan, in rapidly eroding (e.g., desert ) environments, the resulting rock unit is often called a fanglomerate .
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...
A diagram of various depositional environments. In geology, depositional environment or sedimentary environment describes the combination of physical, chemical, and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will be formed after lithification, if the sediment is preserved in the rock record.
These fan-shaped deposits form by the deposition of sediment within a stream onto flat land at the base of a mountain. [1] The usage of the term in landscape description or geomorphology derives from the Spanish word bajada , generally having the sense of "descent" or "inclination".
Aggradation (or alluviation) is the term used in geology for the increase in land elevation, typically in a river system, due to the deposition of sediment. Aggradation occurs in areas in which the supply of sediment is greater than the amount of material that the system is able to transport.
Alluvial fan – Fan-shaped deposit of sediment; Lake Ragunda – Former whitewater rapid on the river Indalsälven, Sweden; Meander – One of a series of curves in a channel of a matured stream; Megafan – Large fan-shaped deposit; River delta – Silt deposition landform at the mouth of a river; River plume – Mix of fresh river water and ...