Downcutting

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San Juan River in Utah can be identified in this 1927 photo. Remnants of former floodplains stand as terraces

above the river's modern level.

Downcutting, also called erosional downcutting, downward erosion or vertical erosion, is a

rejuvenation." This happened in the case of the Colorado River in the western United States, resulting in the process that created the Grand Canyon

Lake bed downcutting

wave action. When the sand cover is stripped away and the cohesive layer is exposed, cohesive material is lost to the water column. Unlike sand, cohesive material cannot be replenished by natural events such as bluff

erosion. This can result in a process called "bluff recession," in which waves erode and carry away the material at the toe of the bluff and cause it to become steeper. When the slope reaches a certain angle, the bluff becomes unstable and fails, causing it to recede inland.

References

Black Hawk College: Fluvial Processes II (Physical Geography 102) Archived 2016-03-03 at the Wayback Machine
U.S. Army Corps of Engineers: Lake Bed Downcutting
Leet, L. Don. Physical Geology, 6th Edition. Englewood Cliffs, NJ: Prentice-Hall, 1982.
ISBN 0-13-669762-3

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