Why is continental crust less dense than oceanic?

Question

Why is it that continental crust is less dense than oceanic, where in fact continental crust is thicker than oceanic crust?

Answer 1

Oceanic crust largely consists of iron and magnesium (very dense metals) whereas continental crust is made up of silicon and aluminum (not very dense elements). Imagine you roll a ball of aluminum foil, and compare the weight of a thin sheet of iron. The iron will feel far much heavier than that huge ball of aluminum because it is so much more dense!

Answer 2

Hi! Continental crust is less dense because of its composition. Continental crust is made up of felsic material (SiO4)-- mainly granite. The density of continental crust is 2.9 g/cm^3. Oceanic crust, while thinner, is made of mafic materials (Fe, Mg)-- mainly basalt. The density of oceanic crust is 3.0g/cm^3.

The amount of material has nothing to do with it's density, since density is a 'per volume' measurement-- the materials that make up the different types of crust have everything to do with their respective densities.