Question

Which concept is described in the theory proposed by Hess?

Continents do not move.
Cool rock pushes through the crust.
Trenches are sites of seafloor spreading.
Mid-ocean ridges are sites of seafloor spreading.

Answer 1

The concept described in the theory proposed by Harry Hess is that **mid-ocean ridges are sites of seafloor spreading**. Hess's theory, known as seafloor spreading, posits that new oceanic crust is created at mid-ocean ridges as magma rises from the mantle, while older oceanic crust is pushed away from the ridges and can be recycled back into the mantle at subduction zones (which are often associated with trenches). This theory contributed significantly to the development of the plate tectonics theory.