. The Earth beneath the sea : History . ^i:i^tiili Fig. 33. Two Precision Depth Recorder records across the Biscay Abyssal Plain. (After Heezen et al., 1959.) ocean basin, a distinct change in the topography will begin to take place. As turbidity currents begin to build up against the seaward side of the oceanic basin, the depositional topography will change character from that resembling the topography of a continental rise to that resembling the topography of the modern abyssal plains. Gradually, as more sediment is supplied, the abyssal plain will widen and fill. If, after some time, tecton
. The Earth beneath the sea : History . ^i:i^tiili Fig. 33. Two Precision Depth Recorder records across the Biscay Abyssal Plain. (After Heezen et al., 1959.) ocean basin, a distinct change in the topography will begin to take place. As turbidity currents begin to build up against the seaward side of the oceanic basin, the depositional topography will change character from that resembling the topography of a continental rise to that resembling the topography of the modern abyssal plains. Gradually, as more sediment is supplied, the abyssal plain will widen and fill. If, after some time, tectonic warping uplifts the edge of the plain or a decrease in turbidity-current activity or a change in the type of turbidity-current sediment takes place, certain portions of the plain will become relic and no longer be receiving turbidity-current sediment. These relic jDlains may be relic because they have been uplifted. Some will have been cut off from land by the subsidence of a new trench, as in the case of the northern "Aleutian Abyssal Plain". There are areas of the sea floor of very gentle relief which are distinctly elevated above the abyssal plains and no longer connected to them. Such an area lies in the center of the Argentine Basin. The very smooth topography in this area of nearly abyssal-plain flatness may mean that this area was at one time an abyssal plain which has later been uplifted and is now cut off from a supply of turbidity currents. The sediment (nearly 2 km) lying beneath this rise may have been partially contributed by turbidity currents before the elevation of the rise. 13—s. Ill
Size: 3931px × 1272px
Photo credit: © The Bookworm Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodivers, booksubjectoceanbottom
