LOCATION SHAGNASTY NVEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Typic Argixerolls
TYPICAL PEDON: Shagnasty extremely stony loam, woodland. (Colors are for dry soil unless otherwise noted.) The soil surface is
partly covered with 15 percent stones, 5 percent cobbles, and 5 percent pebbles.
A--0 to 9 inches; grayish brown (10YR 5/2) extremely stony
loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine through coarse roots; common fine and medium tubular, common fine interstitial pores; 10 percent pebbles, 5 percent cobbles; slightly acid (pH
6.2); clear smooth boundary. (3 to 12 inches thick)
Bt--9 to 12 inches; dark grayish brown (10YR 4/2) cobbly loam, dark brown (l0YR 3/3) moist; moderate fine angular blocky struc- ture; hard, firm, sticky and plastic; many very fine through coarse roots; common fine and medium tubular, common fine interstitial pores; many moderately thick clay films on peds and lining pores;
10 percent pebbles, 20 percent cobbles; slightly acid (pH 6.2); abrupt smooth boundary. (3 to 7 inches thick)
2Bt1--12 to 23 inches; light yellowish brown (10YR 6/4) clay, dark yellowish brown (10YR 4/4) moist; strong medium and coarse prismatic structure; extremely hard, very firm, very sticky and
very plastic; common medium and few fine roots; few fine tubular pores; continuous thick pressure faces on peds; 5 percent cobbles; slightly acid (pH 6.2); gradual smooth boundary. (7 to 14 inches thick)
2Bt2--23 to 36 inches; light yellowish brown (10YR 6/4) clay, dark yellowish brown (10YR 4/6) moist; strong medium and coarse prismatic structure; extremely hard, very firm, very sticky and
very plastic; common medium and few fine roots; few fine tubular pores; continuous thick pressure faces on peds; 5 percent cobbles; slightly acid (pH 6.2); abrupt smooth boundary. (5 to 13 inches thick)
3Bt1--36 to 43 inches; light yellowish brown (10YR 6/4) cobbly silty clay loam, dark yellowish brown (10YR 4/4) moist; weak medium prismatic structure; very hard, firm, sticky and plastic; common medium and coarse and few fine roots; common fine tubular pores; continuous thick clay films on peds; 5 percent pebbles, 15 percent cobbles; slightly acid (pH 6.4); clear irregular boundary. (6 to
20 inches thick)
3Bt2--43 to 59 inches; yellowish brown (10YR 5/4) cobbly silty clay loam, dark yellowish brown (10YR 4/4) moist; massive; very
hard, firm, sticky and plastic; common medium and coarse, few fine roots; common fine and medium tubular pores; many moderately thick clay films on peds and lining pores; 5 percent pebbles, 15 percent cobbles; slightly acid (pH 6.2); clear wavy boundary. (12 to 16 inches thick)
3Cr--59 inches; weathered bedrock.
TYPE LOCATION: Eureka County, Nevada; approximately 36 miles northwest of Eureka in the Simpson Park Mountains; about 2,500 feet south and 2,000 feet west of the northeast corner of section 36, T. 23 N., R. 48 E.
RANGE IN CHARACTERISTICS:
Soil moisture - Moist in winter through early summer, dry mid-July
to October.
Soil temperature - 44 to 46 degrees F.
Mollic epipedon thickness - 10 to 16 inches, includes upper part of argillic horizon.
Depth to base of Bt horizon - 40 to more than 60 inches.
Control section - Clay content: 35 to 50 percent.
Rock fragments: 5 to 15 percent, when mixed.
Depth to weathered bedrock - 50 to 80 inches.
Reaction - Slightly acid to mildly alkaline.
Other features - Some pedons have secondary carbonates below 40 inches. Some pedons lack lithological discontinuity.
A horizon - Value: 4 to 5 dry, 2 or 3 moist.
Chroma: 2 or 3.
Bt horizon - Hue: 7.5YR or 10YR.
Value: 4, 5, or 6 dry, 3, 4, or 5 moist.
Chroma: 3 or 4 in upper part, 4 to 6 in lower part.
Structure: Prismatic or angular blocky or is massive in the lower subhorizons of some pedons.
COMPETING SERIES: These are the
Booford, Marrila,
Ostler and Rob
Roy series. Booford and
Rob Roy soils have bedrock at a depth of
20 to 40 inches. Marrila soils have an argillic horizon 21 to 32 inches thick with its base below 40 inches and lack a discontinuity within 40 inches. Ostler soils lack a discontinuity and are dry
for 50 to 70 consecutive days during the summer.
GEOGRAPHIC SETTING: Shagnasty soils are on mountain side slopes. These soils formed in residuum and colluvium derived from
rhyolite, andesite and quartzite. Slopes are 15 to 50 percent. Elevations of 6,000 to 8,500 feet. The climate is cool, semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 12 to 16 inches; mean annual temperature is 43 to
45 degrees F., and the frost-free season is 50 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Ravenswood,
Segura,
Softscrabble,
Welch and the competing
Walti soils. Ravenswood
soils have clayey-skeletal particle-size control section. Segura soils have a lithic contact within a depth of 20 inches. Softscrabble and Welch have less than 35 percent clay in the particle-size control section.
DRAINAGE AND PERMEABILITY: Well drained; rapid runoff; slow permeability.
USE AND VEGETATION: Woodland, rangeland and wildlife habitat. The vegetation is mainly singleleaf pinyon, Utah juniper and some mountainmahogany with an understory of mountain big sagebrush and Douglas rabbitbrush.
DISTRIBUTION AND EXTENT: North-central Nevada. These soils are moderately extensive.
MLRA OFFICE RESPONSIBLE: Reno, Nevada
SERIES ESTABLISHED: Eureka County, Nevada, 1983.
DIAGNOSTIC HORIZONS AND FEATURES RECOGNIZED IN THIS PEDON ARE:
Mollic epipedon - The zone from the soil surface to about 12 inches (the A and Bt horizons).
Argillic horizons - The zone from about 9 to 59 inches (the Bt,
2Bt1, 2Bt2, 3Bt1 and 3Bt2 horizons).
Paralithic contact - The boundary at about 59 inches (the Cr horizon).
Particle-size control section - The zone from about 9 to 29 inches (the Bt and 2Bt1 horizons and part of the 2Bt2 horizon).