What is the difference between delta, alluvial fan, and submarine fan?
A delta is a build-up of sediment that is now dry land, such as the Mississippi or Nile River deltas. They obviously have many small streams flowing to the ocean, but mostly, they’re dry. Alluvial fans are fan-shaped deposits of sediment transported by moving water. They form at the bases of geographic features like mountains where there is a break in slope. Because of this, alluvial fans are usually very course at their “mouth” but can grade to very fine grained at their edges. There are many classic examples in Death Valley, rather ironic because it’s so at this instant of geologic time. Just for more information for you… if you have what looks like an alluvial fan, but was not transported by water, it’s called “colluvium.” EDIT – When I say that it was transported by water, I still mean that they can be deposited at the mouth of a river and underwater (shallow) or at the base of a dry mountain. Submarine fans are similar to both deltas and alluvial fans, except that they’re… sub
