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 Public and its Problems the public and its potential. Dewey did not call for an abandonment of the public; rather, he hoped the public would regain a sense of self. The solution to this, he writes, is improved communication. Only then, with communication, will the public find itself and become a cohesive group. In addition to Dewey's proposition that the public cannot find itself because there are too many publics, he also blames the distractions of modern society. He points out that even in the past, the public has had other concerns than politics: "Political concerns have, of course, always had strong rivals". In