Submarine canyon
An undersea canyon (also known as submarine canyon ) is a steep valley on the sea floor in the area of the continental shelf . Submarine canyons are typically found as extensions of large rivers. They can be very large. B. the Kongo canyon to 1200 meters below sea level and it extends 800 km far into the sea.
Characteristic
Submarine canyons are more common on steep ocean slopes than on flat ones. They show erosion through all layers from not yet petrified sediment to crystalline rock. The walls are typically very steep. The walls themselves show signs of erosion. Sediments transported through submarine canyons can create deep-sea fans at the base of the canyon .
Formation of submarine canyons
Two mechanisms have been proposed by which submarine canyons can arise, which may have also acted together:
- The canyons may have been eroded at a time when sea levels were lower and the rivers continued to flow out into what is now the shelf area. The problem with this theory is that in this case the sea level must have been 1000 m lower. This applies to the canyons in front of the mouths of the rivers to the Mediterranean Sea (see Messinian salinity crisis ).
- It is possible that these canyons were created by suspension currents (dense, sediment-laden currents) that e. B. triggered by an earthquake and flowing down the continental slope.
literature
- Andrea Fildani: Submarine Canyons: A brief review looking forward . In: Geology . April 1, 2017, doi : 10.1130 / focus042017.1 (open access).
- JA Covault: Submarine Fans and Canyon-Channel Systems: A Review of Processes, Products, and Models . In: Nature Education Knowledge . 2011 ( nature.com ).
Individual evidence
- ↑ Frank Press, Raymond Siever: General Geology - Introduction to the Earth System . 3. Edition. Spektrum Akademischer Verlag, 2003, ISBN 3-8274-0307-3 , pp. 464-467 .