Continental crust

Continental crust

• A. Rock
• B. Sial
• C. Sedimentary Rock
• D. Sea-floor Spreading

Answer: (B)

Continental crust is mainly made of granitic rocks that are rich in silica and aluminium, which is why the term sial is used to describe it. This composition makes the continents buoyant and less dense than oceanic crust, which is richer in silica and magnesium and often described as sima. Saying continental crust is just “rock” is too vague, because the crust isn’t defined by a single rock type; it’s defined by its silica- and aluminium-rich composition. Calling it “sedimentary rock” isn’t accurate either, since the crust includes many igneous rocks like granite, not only sedimentary ones. And sea-floor spreading is a process that creates new oceanic crust at mid-ocean ridges, not a description of the continental crust itself.

Continental crust is mainly made of granitic rocks that are rich in silica and aluminium, which is why the term sial is used to describe it. This composition makes the continents buoyant and less dense than oceanic crust, which is richer in silica and magnesium and often described as sima. Saying continental crust is just “rock” is too vague, because the crust isn’t defined by a single rock type; it’s defined by its silica- and aluminium-rich composition. Calling it “sedimentary rock” isn’t accurate either, since the crust includes many igneous rocks like granite, not only sedimentary ones. And sea-floor spreading is a process that creates new oceanic crust at mid-ocean ridges, not a description of the continental crust itself.