Researchers Find Kilometer-Long Underwater Ridges off Morocco
Ridges stretching for several kilometers have been spotted off Cape Spartel in northern Morocco. Some are more than 20 meters high. Researchers are debating their origin.
Southwest of Cape Spartel, a study published in Geomorphology describes these landforms for the first time. They cover about 30 km², at depths of between 100 and 250 meters.
On maps, three ridges measure 5 to 7 kilometers. Bathymetric and seismic surveys reveal their shape, including beneath the sediments.
Moroccan Atlantic seabeds are already home to numerous landforms built by cold-water corals. A study published in 2019 in Marine Geology had recorded more than 3 400 visible mounds across an area of 1 440 km². Including those buried beneath the seabed, the authors estimated their number at around 16 000.
Dunes or coral formations
For the structures at Spartel, researchers are considering dunes shaped by currents, sandbanks left over from a lower sea level, or accumulations of coral.
These coral formations can remain after the organisms that built them have disappeared. In the 2019 survey, living corals were almost entirely absent, while the mounds remained clearly visible. The accumulated calcareous skeletons thus provide a lasting record of their presence.
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At Spartel, seismic profiles reveal four generations of ridges stacked on top of one another and preserved beneath the sediments.
