Are The Continents Composed Mostly Of Granitic Rock Or Basaltic

The crust is composed of two basic rock types granite and basalt.

Are the continents composed mostly of granitic rock or basaltic. Basalt is the dark heavy volcanic rock that makes up most of the world s oceanic crust. The continental crust is composed mostly of granite. The key difference between basalt and granite is that basalt is mostly occurring on ocean floors while granite is in the crust of the earth in all continents. Because of this the continents ride on the.

Earth contains three kinds of rocks namely igneous rocks sedimentary rocks and metamorphic rocks basalt and granite are two types of igneous rocks. This difference in density allows the continents to float higher on the underlying mantle. Continental crust is typically 40 km 25 miles thick while oceanic crust is much thinner. Some of it erupts on land too but to a first approximation basalt is an oceanic rock.

Why are continents made mostly of granitic rocks and ocean basins mostly of basaltic rocks. Basaltic rocks of the ocean plates are much denser and heavier than the granitic rock of the continental plates. While the ocean basins are composed of mostly basaltic rocks with an average density of 3 0g cm 3. Continental crust is broadly granitic in composition and with a density of about 2 7 grams per cubic cm is somewhat lighter than oceanic crust which is basaltic i e richer in iron and magnesium than granite in composition and has a density of about 2 9 to 3 grams per cubic cm.

The oceanic crust consists of a volcanic lava rock called basalt.