Britannica Sources used in this answer

How does folding and thrusting thicken Earth’s crust?

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

plateau The Columbia Plateau is uniformly covered with basaltic lava flows and spans an area of about 100,000 square miles in Idaho, Washington, and Oregon.

Folding and thrusting thicken Earth’s crust through the process of crustal shortening. This occurs when horizontal compressional forces act upon the crust, causing it to contract in its horizontal dimension.123

In this process, layers of rock are compressed into folds—such as anticlines and synclines—or are broken and stacked on top of one another via thrust faults. Specifically, when one block or slice of crust is pushed over an adjacent one through overthrusting, the vertical stacking of these materials increases the total thickness of the crust.5312

This mechanism is a primary driver in the formation of high-elevation landforms, such as mountain ranges and certain high plateaus, where the crustal thickening supports the elevated surface against the forces of erosion. In intense collision zones, such as the Himalayas, this process can involve the stacking of multiple slices of continental material, significantly increasing the crust's vertical profile.1453