LOCATION TONAHUTU COEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Lamellic Haplocryalfs
TYPICAL PEDON: Tonahutu very gravelly sandy loam, on a southwest facing, convex, 21 percent slope in a Engelmann's spruce forest at an elevation of 9280 feet. (Colors are for dry soil unless otherwise noted.) When described on July 1, 1997 the soil was moist from 0 to 60 inches. The surface is covered by 1 percent stones and 10 percent cobbles.
Oe--0 to 1 inches; moderately decomposed moss and needles. (0 to 2 inches thick)
E--1 to 6 inches; pale brown (10YR 6/3) very gravelly sandy loam, brown (10YR 4/3) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic, many medium and coarse roots, common very fine and fine roots; 25 percent gravel and 11 percent cobble; strongly acid (pH 5.2); abrupt smooth boundary. (3 to 7 inches thick)
E and Bt1--6 to 21 inches; 65 percent pale brown (10YR 6/3) very gravelly sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; and 35 percent lamellae of light yellowish brown (10YR 6/4), very gravelly sandy clay loam, yellowish brown (10YR 5/4) moist; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots, few medium and coarse; few distinct discontinuous clay bridging between sand grains and in root channels and pores; total thickness of lamellae is 1 inch; 40 percent gravel; moderately acid (pH 5.6); clear wavy boundary. (10 to 16 inches thick)
E and Bt2--21 to 35 inches; 55 percent pale brown (10YR 6/3) very gravelly sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; and 45 percent lamellae of light yellowish brown (10YR 6/4), very gravelly sandy clay loam, yellowish brown (10YR 5/4) moist; slightly hard, friable, slightly sticky and slightly plastic; few fine and coarse roots; common distinct discontinuous clay bridging between sand grains and in root channels and pores; total thickness of lamellae is 3 inches; 40 percent gravel; moderately acid (pH 6.0); clear wavy boundary. (9 to 17 inches thick)
Bt and E--35 to 45 inches; 70 percent lamellae of strong brown (7.5YR 5/6) very gravelly sandy clay loam, strong brown (7.5YR 4/6) moist; 25 percent pale brown (10YR 6/3) very gravelly sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; soft, friable, slightly sticky and slightly plastic; few very fine to coarse roots; common distinct discontinuous clay bridging between sand grains and in root channels and pores; total thickness of lamellae is 2.5 inches; 45 percent gravel and 5 percent cobbles; slightly acid (pH 6.2); clear wavy boundary. (8 to 20 inches thick)
BC--45 to 62 inches; light brownish gray (10YR 6/2) very gravelly loamy sand, dark grayish brown (10YR 4/2) moist; weak medium subangular blocky structure; soft; very friable, nonsticky and nonplastic; few fine to coarse roots; 45 percent gravel and 10 percent cobbles; slightly acid (pH 6.4).
TYPE LOCATION: Grand County, Colorado; about 1.1 miles northeast of the Kawuneeche visitors center in Rocky Mountain National Park; about 2,100 feet north and 800 feet east of the southwest corner of sec. 29, T. 4 N., R. 75 W.; Grand Lake USGS quad; lat. 40 degrees 16 minutes 39 seconds N. and long. 105 degrees 49 minutes 18 seconds W., NAD 1927
RANGE IN CHARACTERISTICS: (Depths given are measured from the mineral soil surface)
Soil moisture regime: udic moisture regime
Mean annual soil temperature: 36 to 40 degrees F
Mean summer soil temperature: 43 to 47 degrees F
Depth to lamellae: 6 to 24 inches
Total lamellae thickness: 6 to 20 inches
Base saturation: 60 to 85 percent
Particle-size control section (weighted average):
Clay content: 10 to 18 percent
Sand content: 55 to 80 percent
Rock fragments: 35 to 50 percent gravel and cobbles derived from granite, gneiss, and schist
Mica content: 15 to 30 percent (by grain count)
E horizon:
Hue: 7.5YR or 10YR
Value: 6 to 8 dry, 4 to 6 moist
Chroma: 2 or 3
Clay content: 10 to 18 percent
Rock fragments: 35 to 60 percent
Reaction: strongly acid or moderately acid
E and Bt horizons:
Hue: 7.5YR or 10YR
Value: (E) 6 or 7 dry, 4 to 6 moist
Value: (Bt) 5 or 6 dry, 4 or 5 moist
Chroma: (E) 2 or 3
Chroma: (Bt) 3 to 6
Texture: (E) very gravelly sandy loam, very gravelly coarse sandy loam
Texture: (Bt) very gravelly sandy loam, very gravelly sandy clay loam
Clay content: 5 to 18 percent (E); 15 to 27 (Bt)
Rock fragments: 35 to 60 percent
Base saturation: 60 to 85 percent
Reaction: Strongly acid or slightly acid
Bt and E horizons:
Hue: 7.5YR or 10YR
Value: (Bt) 5 or 6 dry, 4 or 5 moist
Value: (E) 6 or 7 dry, 4 to 6 moist
Chroma: (Bt) 3 to 6
Chroma: (E) 2 or 3
Texture: (Bt) very gravelly sandy loam, very gravelly sandy clay loam
Texture: (E) very gravelly sandy loam, very gravelly coarse sandy loam
Clay content: 15 to 27 (Bt); 5 to 18 percent (E)
Rock fragments: 35 to 60 percent
Base saturation: 60 to 85 percent
Reaction: Moderately acid or slightly acid
BC horizon:
Hue: 7.5YR or 10YR
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 2 to 6
Texture: very gravelly loamy sand, very gravelly sandy loam
Clay content: 5 to 15 percent
Rock fragments: 35 to 60 percent
Reaction: Moderately acid to neutral
COMPETING SERIES: This is the
Troutville (CO) series. In addition, the following soils may be competitors when their classification is updated: the Hyannis(CO),
Origo(NM), and the
Yochum(CO) series.
Hyannis and Yochum soils have bedrock at depths of 20 to 40 inches.
Origo soils have a base saturation of 40 to 60 percent, have less than 10 percent mica.
Troutville soils are bordering an ustic moisture regime, have less than 10 percent mica content, and have rock fragments dominantly 10 to 24 inches in diameter.
GEOGRAPHIC SETTING:
Parent material: till derived from granite, gneiss, and schist
Landform: moraines
Slopes: 15 to 50 percent
Elevation: 8,700 to 11,000 feet
Mean annual temperature: 38 to 42 degrees F
Mean annual precipitation: 24 to 34 inches
Precipitation pattern: uniform throughout the year
Wettest months: March, April and May
Driest months: September and October
Frost-free period: 30 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Enentah and Fallriver series. The Enentah and Fallriver soils do not have an argillic horizon and are on the upper one third of backslopes.
DRAINAGE AND PERMEABILITY: Well drained, rapid to very rapid runoff, moderate permeability in the upper part and rapid in the lower part..
USE AND VEGETATION: Recreation and wildlife habitat. Native vegetation is subalpine fir, Engelmann's spruce, and lodgepole pine with an understory of grouse whortleberry and russet buffaloberry.
DISTRIBUTION AND EXTENT: North central Colorado; LRR E, MLRA 48A. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Grand County, Colorado, Rocky Mountain National Park soil survey area, 1999. The name is from a prominent drainage in the area, and is also the Arapaho word for meadow. Pronounced ton-uh-HOO-too.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 1 to 6 inches. (E horizon)
Argillic horizon composed of lamellae: The zone from 6 to 45 inches. (E and Bt1, E and Bt2, and Bt and E horizons)
Particle-size control section: The zone from 11 to 41 inches. (part of the E and Bt1, the E and Bt2, and part of the Bt and E horizon)
Originally recognized as Troutville but was separated after laboratory data established high mica content.
Keys to Soil Taxonomy: Series classified according to Eighth Edition, 1998.