Which crust is thicker and less dense?

• A. Continental crust
• B. Oceanic crust
• C. Lithosphere
• D. Mantle

Answer: (A)

Understanding the difference between continental and oceanic crust helps explain why one is thicker and less dense. Continental crust is made mostly of granitic rocks, which are less dense, and it sits higher because it is thicker—roughly 30 to 50 kilometers thick, and it can grow thicker under mountain ranges. Oceanic crust, on the other hand, is mainly basaltic, denser, and thinner—about 5 to 10 kilometers thick. So, when asked which crust is both thicker and less dense, continental crust is the best match. The lithosphere is the rigid outer shell that includes the crust and upper mantle, not a crust by itself with these specific properties, and the mantle lies beneath the crust and is much denser.