In geology, what is the primary result of isostasy?

Isostasy is a principle in geology that explains how the Earth's lithosphere (the rigid outer layer) floats on the more fluid, deformable asthenosphere beneath it. This floating, or buoyancy, occurs because the lithosphere is less dense than the underlying asthenosphere, allowing it to maintain equilibrium.

When changes occur—such as the addition of weight from sediment deposition, glacial ice, or the removal of weight due to erosion or melting glaciers—the lithosphere can adjust vertically. This adjustment ensures that the gravitational forces acting on the lithosphere are balanced by the buoyancy of the asthenosphere. Thus, the primary result of isostasy reflects this dynamic balance, which governs large-scale geological processes and landforms.

Other options, such as the formation of sedimentary layers, development of fault lines, and creation of volcanic islands, are influenced by various geological processes but do not directly relate to the concept of isostasy itself. Instead, these processes may occur within the frameworks established by isostatic adjustments. For instance, sedimentary layers can accumulate due to the stability provided by isostatic balance, but they are not the direct result of it. Therefore, the correct answer highlights the fundamental concept of isostasy relating