An Introduction to the Indian Peaks.

An Introduction to the Indian Peaks.

Geologically speaking, the Front Range is bordered on the east by a series of narrow sedimentary cuestas and hogbacks, locally known as the Flat Irons and tectonic depressions to the west and south. The range itself is composed of a core of Precambrian intrusives, themselves intruded by Tertiary plutons.

Looking west towards the Flat Irons from Boulder, Colorado (Photo credit Michael Ritter, 1984)

The Front Range rises from the high plains near Denver, Colorado at approximately 5,280 feet to an elevation of over 13,500 feet. The crestline of the range forms the Continental Divide. The range appears to slope gently to the east as a series of broad benches, described by some as remnants of former erosion surfaces. The topography of the Indian Peaks section has been carved by a combination of fluvial and glacial activity. The surface has been deeply dissected, first by the cutting of river valleys which were later modified by Pleistocene glaciation. Many areas were later affected by Holocene glaciation as well.

Actually, glacial erosion has not advanced very far, so that the higher elevations represent a balance between the steep glacial topography and broadly flowing uplands.Elevations drop precipitously on the west of the continental divide.

Oblique aerial photograph taken from east of Green Lakes Valley (left of center) and Niwot Ridge (the broadening ridge running from center to lower right of image) in July. (Photo used with permission. CULTER http://culter.colorado.edu:1030/)

The strong westerly winds exert an important control over the character of the Front Range environment. Interacting with topography, deposition and accumulation of snow occurs on eastern, lee side situations yielding a predominance of cirque forms with easterly orientations. A similar control is placed on the distribution of perennial and late-lying snow banks affecting the distribution of plant communities.

Four distinct ecosystems are found above the short grass prairie that lies at the base of the range: the colline belt where Ponderosa Pine and Douglas fir dominate;the montane forest which is subdivided into the lower montane with a predominance of lodgepole pine and intermixed aspen and the upper montane of Engelmann spruce, subalpine fir and limber pine; and the treeless alpine tundra.

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Created by Mike Ritter ( mritter@uwsp.edu ). Last revised June 15, 1997. MR