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Consider the following statements regarding the Earth's crust :
I. The continental crust is thinner under fold mountains.
II. The mean thickness of ocean crust is 30 km.
III. The Earth's crust is brittle in nature.
Which of the statements given above is/are correct?
Explanation
Statement I is incorrect. The continental crust is actually thicker under major mountain systems due to the presence of deep crustal roots; for example, it reaches a thickness of about 70 km in the Himalayan region.
Statement II is incorrect. The mean thickness of the oceanic crust is approximately 5 km, while the mean thickness of the continental crust is around 30 km.
Statement III is correct. The Earth's crust is the outermost solid layer and is brittle in nature, meaning it tends to fracture or break when subjected to stress, which is a primary cause of earthquakes.