FLOOD09597

• County: Gunnison
• Community: Marble Area
• Basin: Gunnison
• Title: Engineering Geologic Factors of the Marble Area
• Date: 6/1/1972
• Prepared For: Gunnison County
• Prepared By: Colorado Geological Survey
• Floodplain - Doc Type: Educational/Technical/Reference Information

- 30 ~

indicates strongly dipping Mancos shale beds with vertical jointing.

These facts together with the generally steep slopes are enough to

indicate the need for careful geologic and engineering studies and

extreme caution. The lower part of this area is on the Crystal River

flood plain, and just opposite the confluence with Carbonate Creek

(4c, plate 1). Possible hazards from flooding and mudflows should be
carefully evaluated before construction on this part of the site is

planned.

Area of Unstable Talus and Landslides, North of Landing Strip (5)

This is a sizable, roughly triangle-shaped area north of the land-

ing strip and opposite the confluence of Raspberry Creek and the Cry.,-

stal River. It was mapped as talus by Gaskill (1966), and as active
talus by Hepworth (1971). Our initial photo studies showed scarp and
ridge features that are not typical of a talus slope, since both active

and inactive taluses generally consist of an equilibrium slope of

smooth curvature. Because of its anama10us appearance, further field

and photogeo10gic studies were made of the area.

Field examinations showed that most of the rubble slope consisted

of igneous rock debris which was typical of the Raspberry Creek Phaco-

lith intrusion. The source of the rock debris is an erosionally de-

tached portion of the Phaco1ith that lies just upslope from the area

discussed. This rock is strongly jointed in three directions, and the

regional dip is downslope toward a synclinal axis which is just south

of the Crystal River.
In detail, the surface of the rubble slope consists of sharp curvi-

linear ridges, scarps, and elongate depression features. These, typi-

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