1. n. [Geology]

The value of the separation between two adjacent contours. A net pay isopach map might have a contour interval of 10 feet [3 m], whereas a structure contour map might have a contour interval of 1000 feet [300 m]. Contour intervals are chosen according to the map scale and the amount and distribution of control points.

Alternate Form: CI

See related terms: structure map