Explain the characteristics and formation of submarine canyons.

(1) The submarine canyons are the valleys-like cut deep into the continental shelves and slopes.

(2) They occur around all the coasts of the world.

(3) They are mostly associated with the mouth of the great rivers such as the Hudson, the Mississippi, the Indus, and the Ganga.

The best known canyons in the world occur in Bering Sea of Alaska. They are-Bering, Pribilof and Zhemchug canyon, Hudson canyon.

Formation of Submarine Canyons : They are formed in the following ways :

(i) By Erosive action of River : It is believed that submarine canyons are formed by sub-aerial processes and submarine processes in the Pliestocene period. During this period, the sea level went up and down upto the extent of 100 metres. In the processes of up and down of the sea level, shelves were exposed to river action and other submarine processes. Thus, the canyons were formed by the erosive action of rivers.

(ii) By Faulting : It is also believed that faulting of the coastal areas near the river mouths produced the similar effects and pushed a part of the shelf up. This part of the shelf also had been cut by the rivers in shape of canyons. This view is supported by the presence of faults or bendings along the coasts which have sub-merged the river-cut valleys to become the sub-marine canyons.

(iii) By Turbidity Currents : The turbidity currents eroded the edges of the shelves. This erosive action of the turbidity currents formed the sub-marine canyons.