Abyssal Plain

Abyssal plains are the flat, nearly featureless regions of the deep ocean floor, typically 4,000 to 6,000 m deep, formed where slow-settling pelagic sediment buries the rugged basaltic crust created at the ridge. They are among the flattest surfaces on Earth, with gradients under one part in a thousand, broken only by abyssal hills and the occasional seamount. They flank the deep basins between the mid-ocean ridge and the continental rise.