plunge

geology

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

July 1, 2026

Quick Summary

In geology, "plunge" refers to the vertical angle between a horizontal plane and the axis or line of maximum elongation of a feature. This measurement is taken along the axis of a fold, distinguishing it from "dip," which measures the inclination of a planar feature. The term "plunge" can also describe the act of diving or a sudden drop in level or temperature. While not directly related to geological formations, the term "plunge" is used in the context of intrusive igneous rocks to describe the shape of certain intrusions like lopoliths, which are saucer-shaped with a concave upward roof and floor.12345

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

5 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

fold
…the horizontal, is called the plunge. The portions of the fold between adjacent axes form the flanks, limbs, or slopes of a fold.
Read More
…the horizontal, is called the plunge. The portions of the fold between adjacent axes form the flanks, limbs, or slopes of a fold.
Read More

strike
Plunge is the vertical angle between the horizontal plane and the axis or line of maximum elongation of a feature. Plunge is measured along the axis of a fold, whereas dip is measured along the limbs. Pitch is the angle between the axis of the…
Read More
Plunge is the vertical angle between the horizontal plane and the axis or line of maximum elongation of a feature. Plunge is measured along the axis of a fold, whereas dip is measured along the limbs. Pitch is the angle between the axis of the…
Read More