GEOGRAPHY 12: RIVER FORMATIONS http://webs.cmich.edu/resgi/links.asp?mc=Other%20Resource%20Links&cad=Earth%20Science%20Animations&to=257&tod=River%20Animations. All part of the hydrologic cycle. http://polaris.umuc.edu/cvu/envm/hydro/hydro.html `.
GEOGRAPHY 12:RIVER FORMATIONShttp://webs.cmich.edu/resgi/links.asp?mc=Other%20Resource%20Links&cad=Earth%20Science%20Animations&to=257&tod=River%20Animations
DRAINAGE BASIN: an area of land from which a stream gets its water supply. It is a region that is grained by a single riverWhat type is seen below?
DendriticA branching treelike drainage pattern. In areas of uniform rock, with little distortion by folding or faulting, the rivers develop a random branching network similar to a tree
TrellisA rectangular drainage pattern. It occurs when the rock structure steers streams into a parallel course, with tributaries joining at almost right angles..
The Rhine River
Cut off slope
Point bar or
slip off slope
Formation:When meander bends become giant loops, there is a thin piece of land left between the beginning and the end of the meander. This is the meander neck.
As the river neck becomes very narrow, the river can break through. For a short time, water flows both round the meander (which is now called a backwater) and across the meander neck.
Eventually the river cuts off the backwater completely and flows across what used to be the meander neck. For a short time, an oxbow lake is left behind.
The oxbow lake lasts until it becomes overgrown with weeds and filled in with soil. This happens quite quickly as it is cut off from the main river and therefore doesn't get any water. This is called a MEANDER SCAR
Levees form by the spill-over of sediment during floods. Next to the channel most of the coarse sediment is deposited and finer muds and clays are deposited farther away. Thus, over time these near-channel sand deposits will rise above the floodplain and form natural levees. Extends into a terrace over time-Let’s watch an animation!
ARCUATE DELTA: Has many distributaries that carry water and sediment across a very symmetrical delta that has the shape of an inverted cove ex.NILE RIVER DELTAnumber of distributaries flowing across the delta (eg the Nile delta). An arcuate delta forms when a river meets the sea in a place where the waves, currents, and tides are strong
BIRD’S FOOT DELTA: From the picture, it is quite evident that it does not look like a bird's foot (C) delta as shown below. A bird's foot delta forms where sediment is deposited in relatively calm offshore waters. An example of a bird's foot delta is the Mississippi river delta.
ESTUARINE DELTA:e.g., Seine River of France. This type of delta has a river that empties into a long, narrow estuary that eventually becomes filled with sediment (inside the coastline).When the mouth of a river enters the sea and is inundated (overtaken) by the sea in a mix with freshwater and very little delta, it is called an estuary.Another example would be Delta, British Columbiahttp://www.semi.sd36.bc.ca/mleziva/unit6/U06L02.htm
A cuspate delta is formed when a river drops sediment onto a straight shoreline with strong waves. Waves force the sediment to spread outwards in both directions from the river's mouth making a pointed tooth shape with curved sides. An example is the Tiber delta in Italy.
Alluvial fans:Created by alluvial aggradation (ACCUMULATION) in areas of high relief where bedload-dominated streams flow out of mts onto plain – stream sweeps side to side over time, making fan shape – most common in desert climates