LOCATION BULLWARK CO

Established Series
Rev. LAN/GB/TWH
05/2012

BULLWARK SERIES

The Bullwark series consists of moderately deep, well drained soils that formed in colluvium and residuum from schist, gneiss, and granite. Bullwark soils are on mountain slopes. Slopes range from 5 to 50 percent. The mean annual precipitation is about 21 inches and the mean annual temperature is about 40 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, micaceous Lamellic Haplocryepts

TYPICAL PEDON: Bullwark very gravelly coarse sandy loam, on a east facing, convex, 33 percent slope in forest at an elevation of 9,352 feet. (Colors are for dry soil unless otherwise noted.) When described on July 8, 1998 the soil was moist from 0 to 32 inches. The surface is covered by 8 percent stones, 8 percent cobbles and 3 percent boulders.

Oi--0 to 2 inches; slightly decomposed plant material.

E--2 to 9 inches; light gray (10YR 7/2) very gravelly coarse sandy loam; brown (10YR 5/3) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; common medium and coarse roots and many very fine and fine roots; 25 percent gravel and 10 percent cobbles and 3 percent stones; slightly acid (pH 6.4); clear wavy boundary. (7 to 10 inches thick)

E and Bt1--9 to 15 inches; pale brown (10YR 6/3) very gravelly coarse sandy loam, brown (10YR 5/3) moist (E); weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots and few medium roots; 25 percent gravel and 10 percent cobbles; moderately acid (pH 5.6); lamellae of yellowish brown (10YR 5/4) very gravelly sandy loam, dark yellowish brown (10YR 4/4) moist (Bt); weak fine subangular blocky structure; soft, very friable, slightly sticky and nonplastic; total lamellae thickness of 1.0 inches; moderately acid (pH 5.6); clear wavy boundary.

E and Bt2--15 to 23 inches; pale brown (10YR 6/3) very cobbly sandy loam, brown (10YR 5/3) moist (E); weak medium subangular blocky structure; soft, very friable, slightly sticky and nonplastic; few fine and medium roots; 20 percent gravel and 15 percent cobbles and 3 percent stones; moderately acid (pH 5.6); lamellae of yellowish brown (10YR 5/4) very cobbly sandy clay loam, dark yellowish brown (10YR 4/4) moist (Bt); weak medium subangular blocky structure; soft, very friable, slightly sticky and nonplastic; total thickness of lamellae is 4.5 inches; moderately acid (pH 5.6); clear wavy boundary. (combined thickness of E and Bt horizons is 13 to 30 inches)

Cr--23 to 32 inches; soft decomposed granite and gneiss. (7 to 13 inches.)

R--32 inches; hard granite and gneiss.

TYPE LOCATION: Larimer County, Colorado; about 3.8 miles northwest of the Estes Park in Rocky Mountain National Park; USGS Estes Park topographic quadrangle; lat. 40 degrees 2 minutes 34 seconds N. and long. 105 degrees 33 minutes 38 seconds W., NAD 1927

RANGE IN CHARACTERISTICS: (Depths given are measured from the mineral soil surface)
Soil Moisture: Udic moisture regime bordering on ustic
Mean annual soil temperature is 36 to 40 degrees F.
Mean summer soil temperature is 43 to 47 degrees F.
Depth to paralithic contact: 20 to 40 inches
Rock fragments: 35 to 60 percent in the control section, dominantly gravel
Mica content: 45 to 80 percent (by grain count)

A horizon:(not in all pedons)
Hue: 7.5YR or 10YR
Value: 3 or 4 dry, 2 or 3 moist
Chroma: 1 or 2
Rock fragments: 15 to 35 percent
Reaction: slightly acid or neutral

E horizon:
Hue: 7.5YR or 10YR
Value: 6 or 7 dry, 4 or 5 moist
Chroma: 2 or 3
Clay content: 8 to 18 percent
Rock fragments: 35 to 50 percent
Reaction: strongly acid to slightly acid

E and Bt horizons:
Hue: 7.5YR or 10YR
Value: 6 or 7 dry, 4 or 5 moist (E)
Value: 5 or 6 dry, 4 or 5 moist (Bt)
Chroma: 2 or 3 (E) and 3 to 6 (Bt)
Clay content: 10 to 27 percent
Texture: very gravelly coarse sandy loam, very gravelly sandy loam, very cobbly sandy clay loam, very cobbly sandy loam
Rock fragments: 35 to 60 percent
Base saturation: 70 to 90 percent
Reaction: moderately acid to slightly acid
Lamellae content: the number of lamellae increases with depth

COMPETING SERIES: There are currently no other series in this family. The closely related Meadowlake (WY), Newcomb (CO), and Ohman (T)(CO) series average sandy-skeletal in the particle-size control section.

GEOGRAPHIC SETTING:
Parent material: colluvium and residuum from granite gneiss and schist
Landform: mountain slopes
Slope: 5 to 50 percent.
Elevation: 7,500 to 10,000 feet
Mean annual temperature: 37 to 42 degrees F.
Mean summer temperature: 44 to 46 degrees F.
Mean annual precipitation: 18 to 25 inches
wettest period: March through August
Frost-free period: 30 to 70 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Catamount, Granile, and Nanita soils. Catamount soils have a paralithic contact at depths of less than 20 inches. Granile soils have an argillic horizon and are very deep. Nanita soils have a sandy-skeletal particle-size control section and are very deep.

DRAINAGE AND PERMEABILITY: Well drained; runoff is rapid; permeability is moderate.

USE AND VEGETATION: Bullwark soils are used for woodland and wildlife habitat. Vegetation is mainly lodgepole pine, Rocky Mountain Douglas fir, and Engelmann's spruce with an understory of elk sedge, kinnikinnick and cliff jamseii.

DISTRIBUTION AND EXTENT: Mountains of northern Colorado. LRR E, MLRA 48A. This series is of small extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Larimer County, Colorado, 1999. Rocky Mountain National Park soil survey area.

REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Albic horizon: 2 to 7 inches
Cambic horizon: from 9 to 23 inches
Paralithic contact at 23 inches
Lithic contact at 32 inches
Lamellae: 8 to 22 inches.

This series was originally classified as loamy-skeletal, mixed Alfic Cryochrepts. It was proposed in Roosevelt-Arapaho-Routt National Forest soil survey area for use at the family level.

Taxonomic Version: Eighth Edition, 1998.

ADDITIONAL DATA: NSSL sample S91CO-69-006.

The mineralogy class was changed from paramicaceous to micaceous in 07/2010 by the National Soil Survey Center on request of the responsible MLRA regional office. The change was necessary based on the eleventh edition of the Keys to Soil Taxonomy, 2010.

National Cooperative Soil Survey
U.S.A.