Longs Peak

Geology (Longs Peak)

Title: Rock Types

Entered by: shredthegnar10

Added: 06/28/2010, Last Updated: 06/28/2010

Granite (medium to coarse grained; contains K-feldspar, biotite, quartz) -- most of the rocks in the boulderfield are granite
Gneiss (the rocks with alternating light and dark layers)

Geology (Longs Peak)

Title: Geology of Longs Peak

Entered by: rockdoc53

Added: 10/20/2010, Last Updated: 10/20/2010

Sources: Braddock, W.A. and Cole, J.C., 1990, Geologic map of Rocky Mountain National Park and vicinity, Colorado: U.S. Geological Survey, Miscellaneous Investigations Series Map I-1973, scale 1:50000.

Longs Peak was formed about 1.4 billion years ago as magma intruded older (1.7 billion years) metamorphic rocks forming the Longs Peak-St.Vrain batholith. The intrusion is composed mostly of the Silver Plume Granite, which is a light to medium gray monzogranite to syenogranite with distinctive tabular microcline (feldspar) phenocrysts.

A prominent horizontal band of metamorphic rock (biotite schist/gneiss) is exposed on the north, west and south faces of Longs Peak above 13,200 feet, and the Keyhole route crosses the band on the west side.

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