Which term describes the change in the elevation of the earth's crust over time?

The term that accurately describes the change in the elevation of the earth's crust over time is isostasy. This concept refers to the equilibrium reached when the buoyant forces of the Earth's crust balance with the gravitational forces acting on it. Essentially, the crust floats on the denser mantle, and any changes in mass — such as from glacial melting or sediment deposition — can lead to adjustments in elevation.

Isostatic adjustments occur as the crust responds to forces over time, which can be slow and is driven by processes such as tectonic activity or changes in surface load. When ice sheets melt, for example, the previously compressed crust begins to rebound and rise back to its original elevation, demonstrating isostatic recovery.

The other terms relate to various geological processes but do not specifically address the concept of crustal elevation change: erosion involves the removal of surface materials, hydrolysis pertains to chemical weathering involving water, and weathering generally denotes the breakdown and alteration of rocks at the Earth's surface. Understanding isostasy is crucial for grasping how the Earth's surface evolves in response to both external and internal changes over time.