Answer:
The given blank can be filled with oceanic crust.
Step-by-step explanation:
The oceanic crust refers to the comparatively thin section of the Earth's crust that forms the floor of the ocean basins. In terms of geology, the oceanic crust is comparatively young than the oceanic crust and comprises basalt rock covered by sediments.
The thickness of the oceanic crust is about 4 miles, and it comprises many layers, not involving the covering sediments. The uppermost layer, of approximately 500 meters thickness, comprises the lavas formed of basalt.