Gordon Gulch

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"The Gordon Gulch site lies within Arapahoe National Forest and is divided into Lower and Upper Gordon Gulch. Gordon Gulch (part intermittent part permanent; see map above) joins the North Boulder Creek about 16 km downstream from Green Lakes Valley (GLV)."

2.6 km2   Area

2446 - 2737 m   Elev

5.1 °C   Temp

519 mm   Precip

Parent Field Area:
Boulder Creek Watershed ▲

Lithology

igneous-felsic extrusive, igneous-felsic intrusive, igneous-ultramafic extrusive

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Geology
Topography
Climate
Ecosystems
  • Geology

    • igneous-felsic extrusive
    • igneous-felsic intrusive
    • igneous-ultramafic extrusive

    Geologic map of Gordon Gulch (Gable, 1980)

    Gordon Gulch lies within the upper montane forest, within the Rocky Mountain surface, an area of relatively low relief despite its altitude, and is underlain by Paleoproterozoic biotite gneiss.   This site is underlain by biotite gneiss and is mostly forested. Unlike GLV, it is not affected by the Pleistocene Glaciers. It is characterized by the low-relief remnants of a dissected Tertiary erosion surface in which weathered rock profiles are up to 30 m thick. This dissected Tertiary erosion surface rises gently from 2500m to about 2750 m over distances of 10-20km.

    The Rocky Mountain surface in the Colorado Front Range lies outside the limits of Pleistocene glaciers, and above canyons incised during the Quaternary by rivers draining eastward toward the Great Plains. This region has evolved without substantial tectonic perturbation since the end of the Laramide orogeny at approximately 50 Mya. The lack of rapid erosional perturbations and presence of some areas of hydrothermal alteration produce a landscape in which the depth to the weathering front averages ~8 m, and reaches up to 30 m, as determined from water well drilling records and sparse road-cuts

  • Topography

    2446 - 2737 m elevation (2650 m mean)

    Gordon Gulch is aligned east–west, and, therefore has north- facing and south-facing slopes with differing energy balances, vegetation, and depth to fresh rock . A snowpack develops on north-facing slopes each winter, but winter snowcover is patchy in both time and space on south-facing slopes. The north-facing slopes are dominated by Pinus contorta (lodgepole pine), which grows in dense stands with little to no understory, while south-facing slopes are dominated by Pinus ponderosa (ponderosa pine) wood- lands, with widely spaced trees and grass-herbaceous understory. Tors mark the topography on both slopes, although a greater number occur on south-facing slopes

    In a series of nine soil pits dug through the mobile regolith and into the underlying saprolite, the average depth of mobile regolith was greater on sites on north-facing slopes (50–75cm vs. 20– 70 cm). The hand excavations of saprolite extended to greater depths on north-facing slopes as well (30–65 cm vs. 20–45 cm), owing to material that was easier to dig through on north-facing slopes, giving a qualitative sense of more weathered saprolite on north-facing slopes. Shallow seismic refraction surveys rein- force this impression: depth to seismic velocities of >3500 m/s characteristic of fresh crystalline rock were on average 15 m on north-facing slopes and 5–10 m on south-facing slopes in catch- ment-crossing transects.

  • Climate

    5.1 °C Mean Annual Temp
    16 °C Mean Warmest Month
    -4 °C Mean Coldest Month
    519 mm Mean Annual Precipitation

    Mean temperatures and precipitation are based on meteorological data collected from 1950-1970 at Sugarloaf (2591m) (Barry, 1973).

    Gordon Gulch is within the montane climatic zone. The maximum precipitation is received around May, with a minimum in the winters.  Gordon Gulch is within the montane climatic zone. The maximum precipitation is received around May, with a minimum in the winters. The forests on the north-facing slopes are generally more lush. The south-facing slopes have fewer trees and more undergrowths.

  • Ecosystems

    The forests on the north-facing slopes are generally more lush. The south-facing slopes have fewer trees and more undergrowths.