Oceanic crust Oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of a tectonic plate. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic cumulates. The crust overlies the solidified and uppermost layer of the mantle. The crust and the solid mantle layer together constitute oceanic lithosphere. Oceanic crust is primarily composed of mafic rocks, or sima, which is rich in iron and magnesium. It is thinner than continental crust, or sial, generally less than 10 kilometers thick; however it is denser,
What Shall We Do Now? the form of a fist that becomes a hammer (a hammer that would reappear in the animated sequence of "Waiting for the Worms"). "What Shall We Do Now?" would be performed at all concerts for "The Wall", and so appears on "Is There Anybody Out There? The Wall Live 1980–81". It was also included in Waters' 1990 "The Wall" Concert in Berlin, therefore appears on the album "The Wall – Live in Berlin". Waters also performed it on his 2010-2013 tour. What Shall We Do Now? "What Shall We Do Now?" (working title "Backs to the Wall") is a song