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 We Do What We Do What We Do is the second studio album by jazz group The John Scofield Quartet. It was recorded in May 1992 and released the following year on the Blue Note label. Besides John Scofield on guitar, the quartet features saxophonist Joe Lovano, Bill Stewart on drums and Dennis Irwin on bass, replacing Marc Johnson. Irwin and Scofield (both born in 1951) had already recorded together in the mid-1980s with Bennie Wallace on a track for his album "Sweeping Through the City." Irwin would be the bassist on two more albums by Scofield, "Hand Jive" (1994) and "Groove