Which statement about the earth’s crust is correct?
a. Continental and oceanic crusts have the same weight.
b. Continental crust is heavier than oceanic crust.
c. Continental crust is thicker than oceanic crust.
d. Oceanic crust is thicker than continental crust.
The correct answer and explanation is:
The correct answer is c. Continental crust is thicker than oceanic crust.
The Earth’s crust is divided into two types: continental crust and oceanic crust. Continental crust is generally thicker than oceanic crust. On average, continental crust has a thickness of about 30-50 kilometers, while oceanic crust is much thinner, typically ranging from 5 to 10 kilometers in thickness.
This difference in thickness is one of the major distinctions between the two. The continental crust is composed mostly of lighter, less dense rocks like granite, while the oceanic crust consists mainly of denser rocks like basalt. As a result, the continental crust floats higher on the mantle compared to the denser oceanic crust, which tends to “sink” deeper into the Earth’s interior.
In terms of weight, although the oceanic crust is thinner, it is denser than the continental crust. This means that if you were to compare the overall mass per unit area, the oceanic crust might outweigh the continental crust in some areas, despite being thinner. However, the significant thickness of the continental crust gives it a greater volume overall.
The difference in thickness is also a key factor in the formation of landforms like mountains, which are found primarily on the continental crust. Oceanic crust, on the other hand, forms the seafloor and is generally flatter and more uniform.
Understanding these distinctions is essential when studying plate tectonics and the movement of Earth’s lithospheric plates, as the varying thicknesses of the crust play a crucial role in the behavior of earthquakes, volcanic activity, and mountain formation.