how is the formation of an alluvial fan similar to the formation of a delta
River delta In both of these cases, depositional processes force redistribution of deposition from areas of high deposition to areas of low deposition. This results in the smoothing of the planform (or map-view) shape of the delta as the channels move across its surface and deposit sediment. Because the sediment is laid down in this fashion, the shape of these deltas approximates a fan. The more often the flow changes course, the shape develops as closer to an ideal fan, because more rapid changes in channel position results in more uniform deposition of sediment on the delta front. The Mississippi and Ural River deltas, with their bird's-feet, are examples of rivers that do not avulse often enough to form a symmetrical fan shape. Alluvial fan deltas, as seen by their name, avulse frequently and more closely approximate an ideal fan shape.
Humboldt Current The current extends from the southern Chile (~45’S) to northern Peru (~4’S) where cold, upwelled waters intersect warm tropical waters to form the Equatorial Front.[1] Sea surface temperatures off the coast of Peru, around 5’S, reach temperatures as low as 16’C.[2] This is highly uncharacteristic of tropical waters, as most other regions have temperatures measuring above 25’C. Upwelling brings nutrients to the surface, which support phytoplankton and ultimately increase biological productivity.[1]