Fluvial Processes

• A dendritic pattern happens in spots where the bedrock is uniform, lies flat, and erodes in a uniform pattern. This is common and tree-like in appearance.

• A trellis pattern happens when there has been a lot of earth-folding and differential erosion in rocks that are not flat. There might be ridges of resistant rock that prevent flow in one or more areas. This is seen in the eastern section of the US in the area of the Appalachians.

• A rectangular pattern where the pattern of joints and faults determine where the streams are located and drain. It looks like a tree with square branches.

• Radial patterns are seen where streams flow down from a mountaintop or top of a cone-shaped volcano. Each stream might have a dendritic pattern of its own.

• Deranged patterns have no real pattern and can involve streams disappearing into subterranean areas or underground streams.

FLUVIAL PROCESSES

Streams also behave differently based on their fluvial processes. These are a combination of factors called fluvial processes. Fluvial processes are those things that affect the way a stream flows and why it is the way it is. These include the following:

• Erosion – erosion itself is due to materials carried down and abrading the river bottom, rocks that become round to nothing, the hydraulic action of the water against rock, and chemical corrosion from acidic water.

• Transportation – eroded material must go somewhere. It tends to go downstream. Some rocks are large and roll slowly along the bottom, while others bounce along the bed of the stream. This is called saltation. Small particles are suspended in the liquid and anything dissolvable in water may stay in solution.

• Deposition – this happens after the river has lost its energy and cannot transport anymore. Things just get deposited then, in places like estuaries or deltas. Where water velocity is slower, you might also get deposition upstream somewhere.

Rivers will meander more if they are slower-moving.