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,
The Core through the crust underwater, leaving them safe on the ocean floor, but power and communications are offline. They believe themselves lost underwater but use the remaining power to activate a weak sonar beacon. The beacon attracts a nearby whale pod, and Finch is able to trace their whale songs to locate the "Virgil". A week after the mission, Finch unleashes the full details of the mission (including those lost) and of DESTINI to the public via the Internet. "The Core" had out-to-sea scenes, starring , with full support of the US Navy. The film garnered mixed reviews. The film received