A floodplain forms where a stream cuts mainly side to side. Hope this helps
The lithosphere is Earth's outermost layer, composed of rocks in the crust and upper mantle that behave as brittle solids. ... The lithosphere is broken into large pieces called plates, which are made up of either seafloor lithosphere (mostly basalt) or continental lithosphere (less dense rocks, like granite).
The question here is what does "sink under the ocean" mean. Under the ocean is the ocean floor-which is part of the oceanic crust. So if two plates meet, one of them can sink below the other -in this sence, it is true that the other plate can partially sink under the ocean.
