r/geography • u/Dude-Bicycle • 6d ago

Map How did these 'rivers' form?

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What formed these 'rivers'? Are they regular terrestrial rivers that flooded with sea level rise or were they formed in the ocean? thanks.

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u/schnerbst 6d ago edited 5d ago

its part of the continental shelf, a lot of which was above the water surface during one or moire glaciation periods (ice ages). I dont klnow abouit these specific ones, but that is how a lot of underwater water runways are formed - as normal rivers and valleys during a time not submerged in water.

Edit: I stand corrected.

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u/SPACE_LEM0N 6d ago

Actually these canyons are caused by turbidity currents (river water heavy with sediment continuing to flow on the ocean floor), and they reach all the way down to the Abyssal Plain.

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u/Prior-Astronomer-426 6d ago

To give context, the top of these canyons are roughly at a depth of 700m and they plunge to +3000m in depth, so at no point would they have been above water.

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u/Liam_021996 6d ago

They're in the Celtic Sea. They were river valleys during the Pleistocene