An interplain deep-sea channel system

A system of channels connecting the Biscay and Iberia plains was discovered in 1958. Two main channels cut through the sill and join after 20 miles. The total length between plains is 50 miles and the width of the channels varies from 2 to 10 miles. The change of level between plains occurs where the channel first leaves the upper plain. The channel shows a meander formation similar to a subaerial river. Cores show that turbidity currents have been active in the past. Small feeding channels on the Biscay plain converge on the interplain channels.

It is concluded that turbidity currents initiated on the continental shelves and flowing across the Biscay plain can be rejuvenated by the increase in gradient and lateral constriction, and flow through to the Iberia plain where they finally deposit their load.