An antecedent stream is a stream that maintains its original course and pattern despite the changes in underlying rock topography. A stream with a dendritic drainage pattern, for example, can be subject to slow tectonic uplift. However, as the uplift occurs, the stream erodes through the rising ridge to form a steep-walled

gorge A canyon (; archaic British English spelling: ''cañon''), gorge or chasm, is a deep cleft between escarpments or cliffs resulting from weathering and the erosion, erosive activity of a river over geologic time scales. Rivers have a natural tend ...

. The stream thus keeps its dendritic pattern even though it flows over a landscape that will normally produce a trellis drainage pattern.Grotzinger, J. & Jordan, T.H. 2006. Understanding Earth, 5th ed., Freeman, New York A superimposed stream is a

stream A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a strea ...

that forms over horizontal beds that overlie folded and faulted rock with varying resistance. Having cut down through the horizontal beds, the stream retains its course and pattern as it proceeds to erode the underlying rocks despite their different character. The stream erodes a gorge in the resistant bed and continues its flow as before.

Examples

* Many Himalayan rivers are good examples of antecedent origin. These rivers originated well before the Himalayan region was uplifted. The rivers

Indus The Indus ( ) is a transboundary river of Asia and a trans- Himalayan river of South and Central Asia. The river rises in mountain springs northeast of Mount Kailash in the Western Tibet region of China, flows northwest through the dis ...

Brahmaputra The Brahmaputra is a trans-boundary river which flows through Southwestern China, Northeastern India, and Bangladesh. It is known as Brahmaputra or Luit in Assamese, Yarlung Tsangpo in Tibetan, the Siang/Dihang River in Arunachali, and ...

Sutlej The Sutlej River or the Satluj River is a major river in Asia, flowing through China, India and Pakistan, and is the longest of the five major rivers of the Punjab region. It is also known as ''Satadru''; and is the easternmost tributary of t ...

, Kosi and Subansiri originated on the Tibetan side and now traverse the existing mountain ranges, cutting deep gorges. * The

Colorado River The Colorado River () is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and in northern Mexico. The river, the List of longest rivers of the United States (by main stem), 5th longest in the United St ...

cut the

Grand Canyon The Grand Canyon is a steep-sided canyon carved by the Colorado River in Arizona, United States. The Grand Canyon is long, up to wide and attains a depth of over a mile (). The canyon and adjacent rim are contained within Grand Canyon Nati ...

as the Colorado Plateau rose between 5 and 2.5 million years ago. Paradox Valley is another good example in the Colorado Plateau. * Devil's Gate in Wyoming is a remarkable display of an antecedent stream. A 100-meter slot is cut through a granite ridge which would have missed the ridge completely had the river flowed just a kilometer to the south. * The

Meuse The Meuse or Maas is a major European river, rising in France and flowing through Belgium and the Netherlands before draining into the North Sea from the Rhine–Meuse–Scheldt delta. It has a total length of . History From 1301, the upper ...

still flows south-north from France to Belgium through the

Ardennes The Ardennes ( ; ; ; ; ), also known as the Ardennes Forest or Forest of Ardennes, is a region of extensive forests, rough terrain, rolling hills and ridges primarily in Belgium and Luxembourg, extending into Germany and France. Geological ...

which were elevated after the river had assumed that course.

References

{{Rivers, streams and springs Hydrology Geomorphology

Examples

See also

References