What factor primarily controls the elevation of a region?

The elevation of a region is primarily controlled by the thickness of the underlying crust. In tectonic terms, regions with thicker crust typically sit at higher elevations compared to those with thinner crust. This is due to the principles of isostasy, which describe how Earth's lithosphere floats on the semi-fluid asthenosphere beneath it.

When the crust is thicker, it displaces more mantle material, leading to higher elevations. For instance, the Himalayan mountain range has an exceptionally thick crust due to the collision of tectonic plates, resulting in its towering height. In contrast, areas with a thinner crust, such as oceanic regions, tend to be much lower in elevation, often below sea level.

While factors like proximity to oceans, earthquake activity, or climate conditions can influence how we perceive the landscape and may indirectly affect elevations through erosion or sediment deposition, they do not fundamentally control the elevation in the same way that the thickness of the crust does.