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,
Where Do We Come From? What Are We? Where Are We Going? Where Do We Come From? What Are We? Where Are We Going? Where Do We Come From? What Are We? Where Are We Going? is a painting by French artist Paul Gauguin. Gauguin inscribed the original French title in the upper left corner: D'où Venons Nous / Que Sommes Nous / Où Allons Nous. The inscription the artist wrote on his canvas has no question mark, no dash, and all words are capitalized. In the upper right corner he signed and dated the painting: "P. Gauguin / 1897". The painting was created in Tahiti, and is in the Museum of