What does a measure of value in terms of a fixed point assess?

A measure of value in terms of a fixed point, such as sea level, assesses the elevation of various geographic locations relative to that established point. This reference provides a standardized way to express altitude or depth, allowing for comparisons between different areas. For instance, when discussing the elevation of a mountain or the depth of a lake, using sea level as a baseline makes it clear how high or low a location is in relation to this common point.

In the context of the other options, while average elevation across a landscape could involve multiple points of reference, it does not focus on a single fixed point like sea level. Assessing distance from a geographical feature could imply variance without a direct point of reference, and the overall health of an ecosystem typically involves qualitative and quantitative measures that do not hinge on a specific fixed point for evaluation. Therefore, measuring value concerning a fixed point effectively communicates the relative positioning of features in the landscape.