The general term is seafloor. Along the edges of large land masses, the continental shelf is part of the seafloor.
Sedimentary rocks formed under oceans, but the ocean may no longer be there. The Great Lakes region was once all under water and has much sedimentary rock.
Yes, the Grand Canyon was once submerged under an ocean millions of years ago.
it was big and ugly
continental
Pangea
land
All of the mammals in the ocean once lived on land. Whales, dolphins, sea lions and seals.
Techtonic plates move under the earth moving land and water.
The continental crust is the land. The oceanic is under the ocean.
The land under an ocean at the edge of a continent is called the continental shelf. This is the shallow submerged portion of a continent that extends from the shoreline to the continental slope.
Oceanic Crust
this is the crust which is the very thin layer which has land in the water