. The Earth beneath the sea : History. Ocean bottom; Marine geophysics. 258 HKRZEN AND MENARD [chap. 12 It is 1-5 miles wide and has 10-100 fm relief below an abyssal plain. Except where it passes through a narrow gorge in a submarine mountain range, it is steep-walled, Hat-iloored, and generally flanked by levees. A very similar feature, the Equatorial Atlantic Mid-Ocean Canyon, has been subject to a rather detailed siu'vey which has confirmed the continuity of the canyon for several hinidred miles. Although incomplete, the study suggests that the mid- ocean canyon disappears somewhere on the
. The Earth beneath the sea : History. Ocean bottom; Marine geophysics. 258 HKRZEN AND MENARD [chap. 12 It is 1-5 miles wide and has 10-100 fm relief below an abyssal plain. Except where it passes through a narrow gorge in a submarine mountain range, it is steep-walled, Hat-iloored, and generally flanked by levees. A very similar feature, the Equatorial Atlantic Mid-Ocean Canyon, has been subject to a rather detailed siu'vey which has confirmed the continuity of the canyon for several hinidred miles. Although incomplete, the study suggests that the mid- ocean canyon disappears somewhere on the continental rise and does not connect with a submarine canyon. Some question exists, therefore, as to A\hether what appear to be identical morphological forms are actually the same. All known deep-sea channels extend without interruption from the continental slope portions of submarine canyons to deep-sea fans or cones to abyssal plains, and they are clearly the channels followed by turbidity currents. M!rv-Oci-_\N OxNvoN No, 2 ff-w-iimpHiiiiiiPiiimpiil *»» ijrj::3l Mid-Ocean Canyons in" HA-rniiiAs AcissAL Pi-ajn, West or Vem* Gap Fig. 21. records of Mid-Ocean Canyon No. 2 and mid-ocean canyons at Vema Gap. Position of Vema Gap and Mid-Ocean Canyon No. 2 as indicated in Fig. 3. Depth in fathoms. (After Heezen et al., 1959.) originating at the heads of the canyons. Each mid-ocean canyon discovered in the North Atlantic, on the other hand, leads to an abyssal gap in a manner suggesting a genetic relationship. It is not known whether these mid-ocean canyons connect to submarine canyons. Mid-ocean canyons or deep-sea channels (if they are not the same thing) have been found by random crossings on several abyssal plains and it would appear that they are widespread (Fig. 21). All recognized mid-ocean canyons in the parallel the adjacent continental margin, suggesting a tectonic control. Although all have a continuous downward slope, they cut across the regio
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