Publication Date:
2022-07-19
Description:
The portion of the continental shelf off Spanish Sahara lying between 23° 00' N and 22° 18' N is 80 km wide, flattens slightly between 40 and 60 m and breaks to the slope at 110 m. Over 200 nautical miles of side-scan sonar profiles were run in both reconnaissance and detail track configuration. Each survey covered a strip of the bottom ca. 280 m wide. A sediment distribution pattern which appeared to have complex lateral variation was revealed to be the result of
a) "windows" in a thin, fine-grained upper sand layer exposing a coarse-grained sand below. In outline these windows run the full range from strongly parallel strips (width ca. 20 m) to irregularly bounded, somewhat elongate forms (width over 200 m). They all exhibit a preferred orientation parallel to the isobaths;
b) Outcrops of probable semi-lithified and truncated Pleistocene sand dunes at depths between 30 and 80 m. Other outcrops are thought to belong to Pleistocene beachrock and pre-Pleistocene strata;
c) Fields of the pelecypod Pinna ramulosa in water depths between 48 and 57 m with characteristic acoustic reflections;
d) Largescale, wave-formed ripples as well as current-formed megaripples.
The side-scan interpretation was corroborated through underwater TV observations, coring, samling, and air-gun profiling.
Type:
Article
,
PeerReviewed
Format:
text
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