2024-05-17_REVISION - M1977493 (3)

Home Browse Search

Permit M-1977-493—Climax Mine Technical Revision 37 (TR-37) Map Unit: 754Y Howardsville family - Rock outcrop complex, 40 to 150 percent slopes. Ecological Land Unit: 754Y—bristlecone pine, subalpine fir and Engelmann spruce on subalpine, south facing mountains. MAP UNIT SETTINGS Location: mountainous areas where igneous and metamorphic rocks predominate. Landform: mountains. Parent material: colluvium and residuum. Geologic symbol: Tmi, Xb, Xfh, Xg, Yg, and YXg. Elevation range: 10,000 to 11,800 feet. Aspect: south. Climatic zone: subalpine. Mean annual precipitation: 20 to 40 inches. Mean annual air temperature: 34°F. to 40°F. Average annual snowfall: 200 to 400 inches. COMPOSITION 55 percent Howardsville and similar soils. 30 percent Rock outcrop. Contrasting inclusions 15 percent shallow soils on convex slopes. TYPICAL PROFILES: Howardsville The Howardsville series consists of very deep, somewhat excessively drained soils that formed in alluvium derived mainly from rhyolite, tuff, and similar volcanic rocks. Howardsville soils are on fan remnants and river terraces. Slopes range from 1 to 6 percent. Mean annual precipitation is about 25 inches and the mean annual temperature is about 35 degrees F. TAXONOMIC CLASS: Sandy-skeletal, mixed Ustic Haplocryepts TYPE LOCATION: San Juan County, Colorado; near Durango and Silverton Narrow Gauge Railroad yard, south of Silverton, located about 1,000 feet east and 300 feet north of the southwest corner of Sec. 17, T. 41 N., R. 7 W.; Silverton USGS quad; lat. 37 degrees 48 minutes 18 seconds N. and long. 107 degrees 39 minutes 46 seconds W., NAD 27 A-- 0 to 2 inches; dark grayish brown (10YR 4/2) gravelly loam, black (10YR 2/1) moist; moderate fine granular structure; soft, friable, nonsticky and nonplastic; 15 percent gravel, 5 percent cobbles; slightly acid (pH 6.2); clear smooth boundary. (2 to 6 inches thick) Bw--2 to 10 inches; brown (7.5YR 5/4) very gravelly sandy loam, dark brown 7.5YR 3/4) moist; weak fine granular structure, soft, friable, nonsticky and nonplastic; 30 percent gravel, 10 percent cobbles, and 2 percent stones; moderately acid (pH 6.0); clear wavy boundary. (6 to 20 inches thick) C--10 to 60 inches; light brown (7.5YR 6/4) extremely cobbly loamy sand, dark yellowish brown (10YR 4/4) moist; single grain; loose, nonsticky and nonplastic; 30 percent gravel, 25 percent cobble, and 10 percent stone; moderately acid (pH 5.8). Rock Outcrop Exhibit I —Appendix A I-A-17 March 2024