Chapter 11.3b Mountain Formation

Mountain Building at Divergent Boundaries Mountains can form at divergent boundaries on the ocean floor. These are fault-block type of mountains. The Mid-Atlantic Ridge is an example.

Non-Boundary Mountains Volcanic mountains – like the Hawaiian Islands form from a hot spot. Many fault- block mountains happen in areas that are stretching, these areas may become a plate if it breaks apart.

Continental Accretion Accretion is when crustal fragments collide with a continental plate and they become stuck together. This will form mountains.

Terranes Terrane is any crustal fragment that has geologic history different from the adjoining terranes.

Mountains from Accretion If a large fragment collides with continental crust it may form mountain ranges. These are not large mountain ranges.

Principle of Isostasy There can be vertical movement of plates. The idea of a floating crust is called isostasy. Isostatic adjustment is when a new level of gravitational equilibrium is established. We will talk about this in class.