What Is An Island Range?

Montana's Crazy Mountains are an example of an island range due to its separation from larger ranges.
Montana's Crazy Mountains are an example of an island range due to its separation from larger ranges.

In simple terms, the term refers to a series of mountains that exist in singularity and separated from a bigger series of ranges or sub-ranges. If looked at from a plain field, island ranges look like islands of elevated ground against a flat area. They acquire the “island” reference due to their existence in the “sea” of lower altitude and other flatter regions. Because of their isolation, island ranges provide special habitats that are homes to some species of plants and animals that are specific to these areas and are not to be found in any other places.

Habitat and Range

The isolation of island ranges provides specific ecological conditions to some species of living organisms that enable them to exist only in that region. This state of ecological uniqueness for some organisms is referred to as endemism. The other term for this condition is precinctive.

There are a lot of island ranges with most of them being found in the Rocky Mountains. These comprise of the Big Snowy Mountains that are found in east-central part of Montana, the Crazy Mountains located in the South-central region of Montana, and the Wichita Mountains situated in Oklahoma. Other isolation in Montana includes the Little Belt Mountains, the Castle Mountains, Bull Mountains, Little, Snowy Mountains, Sweet Grass Hills, and the Highwood Mountains.

Examples of Island Ranges in North America

Big Snowy Mountains

The Big Snowy Mountains is a mountain range found in Fergus County, Montana with an elevation of 2,646 m. A big part of the range does not have roads, mostly found in the Lewis and Clark National Forest and a smaller part of the Twin Coulees. The Big Snowy Mountains are seen as a long east to west summit that rises above a tree line, then crowns into a Greathouse Peak, representing the highest point. The life forms on this island range include trees; like the douglas-fir, the ponderosa pines and the subalpine fir, the wildlife includes the black bear, deer, the pronghorn and rattle snakes.

Crazy Mountains

The Crazy Mountains is an island range in the Rocky Mountains of Montana. It covers a whole 40 miles, with its highest peak, the Crazy Peak, rising to 11,214 feet. These islands offer a spectacular sight rising above the Great Plains. The mountains are drier and less forested than other ranges in Montana. The Crazy Mountains has about 40 alpine lakes, 15 of which are named. It is home to mountain goats and the mysterious wolverine.

Wichita Mountains

The Wichita Mountains of Oklahoma formed as a result of a botched continental rift. The highest point is the Haley Peak which rises to an altitude of 2,481 ft. (756 m). The range slopes towards the eastern side which offers an altitude of 1,000 feet (305 m). This is scenic considering the area is dominated by smooth rolling grasslands. The mountains offer a site for numerous institutions including the ranches, quarries and the US Army operations. The wildlife found in these mountains include the bison, elk, deer and a herd of Longhorn cattle.


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