GEOLOGY

Detailed explanation-1: -Oceanic crust is generally composed of dark-colored rocks called basalt and gabbro. It is thinner and denser than continental crust, which is made of light-colored rocks called andesite and granite. The low density of continental crust causes it to “float” high atop the viscous mantle, forming dry land.

Detailed explanation-2: -The continental crust is composed of granitic rocks, which have even more silicon and aluminum than the basaltic oceanic crust and are less dense than basalt.

Detailed explanation-3: -Mid-Ocean Ridge Geochemistry and Petrology* On average, oceanic crust is 6–7 km thick and basaltic in composition as compared to the continental crust which averages 35–40 km thick and has a roughly andesitic composition.

Detailed explanation-4: -As stated, oceanic plates are denser than continental ones. This is because they are made of denser rocks. Oceanic plates are typically composed of basalt. Basalts are mafic igneous rocks, which means they have a silica (quartz) content of less than 20% and are created by the cooling of lava.

Detailed explanation-5: -The answer lies in the composition of the rocks. Continental crust is composed of granitic rocks which are made up of relatively lightweight minerals such as quartz and feldspar. By contrast, oceanic crust is composed of basaltic rocks, which are much denser and heavier.