A riegel (from German, literally ''crossbar'') is a transverse ridge of
bedrock
In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet.
Definition
Bedrock is the solid rock that underlies looser surface material. An exposed portion of be ...
that has been exposed by
glacial erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is dist ...
. Riegels are also known as rock bars, thresholds, and verrous. They are found in glaciated valleys, and are often associated with
waterfall
A waterfall is a point in a river or stream where water flows over a vertical drop or a series of steep drops. Waterfalls also occur where meltwater drops over the edge of a tabular iceberg or ice shelf.
Waterfalls can be formed in severa ...
s and zones of rapids when streams are present. When multiple riegels are stacked in a series they are referred to as a ''glacial stairway''.
Most riegels can be identified by having smooth faces on the up-valley sides, while the down-valley sides show signs of having been plucked (eroded by the removal of rocks and blocks from the bedrock).
References
{{reflist
www.proz.com, March 5th, 2007www.answers.com, March 5th, 2007
Glacial landforms