Hypsometry

Hypsometry (from Ancient Greek ὕψος (húpsos) 'height' and μέτρον (métron) 'measure')[1][2] is the measurement of the elevation and depth of features of Earth's surface relative to mean sea level.

[4] On other planets within this solar system, elevations are typically unimodal, owing to the lack of plate tectonics on those bodies.

[citation needed] A hypsometric curve is a histogram or cumulative distribution function of elevations in a geographical area.

Subsequent research using two-dimensional landscape evolution models has called the general applicability of this fit into question,[6] as well as the capability of the hypsometric curve to deal with scale-dependent effects.

These graphs can be used to predict various characteristics of lakes such as productivity, dilution of incoming chemicals, and potential for water mixing.

Hypsography of the Earth. Notice that Earth has two peaks in elevation, one for the continents, the other for the ocean floors.
Hypsometric curve of Earth as a histogram.