LOCATION FIREBRICK CA
Established Series
CES/AGB
09/2025
FIREBRICK SERIES
The Firebrick series consists of shallow and very shallow, well drained soils formed in residuum from sandstone. The Firebrick soils are on hills. Slopes range from 1 to 30 percent. The mean annual precipitation is about 570 mm and the mean annual air temperature is about 17 degrees C.
TAXONOMIC CLASS: Loamy, mixed, semiactive, thermic, shallow Typic Haploxerults
TYPICAL PEDON: Firebrick gravelly sandy loam on a west-facing (270 degree), 8 percent slope at an elevation of 113 meters. Vegetation is chamise, manzanita, bush monkey flower, yerba santa, and annual grasses. Colors are for dry soil unless otherwise noted. When described on Friday, May 3, 1996 the soil was dry to 10 centimeters, and moist below.)
A--0 to 10 cm; reddish brown (5YR 4/3) gravelly sandy loam, dark reddish brown (5YR 3/3) moist; 7 percent clay; weak medium and coarse subangular blocky parting to weak medium and coarse granular structure; slightly hard, very friable, slightly sticky, slightly plastic; few medium and coarse, common very fine, and few fine roots throughout; common very fine and fine tubular and common very fine interstitial pores; 20 percent subrounded ironstone gravel, 5 percent subrounded ironstone cobbles; very strongly acid (pH 4.5); clear smooth boundary. (5 to 12 cm thick) Lab sample # 97P00417
Bt1--10 to 28 cm; reddish brown (5YR 5/4) sandy loam, reddish brown (5YR 4/4) moist; 13 percent clay; weak medium and coarse subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; few fine, medium, and coarse roots; common very fine and fine tubular pores; 10 percent clay films on sand and gravel; very strongly acid (pH 5.0); clear wavy boundary. (7 to 25 cm thick) Lab sample # 97P00418
Bt2--28 to 38 cm; reddish yellow (5YR 6/6) sandy clay, 20 percent pinkish gray (5YR 6/2) and 80 percent yellowish red (5YR 5/6) moist; 46 percent clay; weak fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky, moderately plastic; few fine, medium, and coarse roots throughout; common very fine and fine tubular pores; 10 percent clay films in root channels and/or pores and 75 percent clay films on faces of peds and on gravel; extremely acid (pH 4.1); abrupt wavy boundary. (9 to 20 cm thick) Lab sample # 97P00419
2Crt--38 to 75 cm; pink (7.5YR 7/4) moderately coherent sandstone bedrock, pale brown (10YR 6/3) moist; white (10YR 8/1) grayish brown (10YR 5/2), reddish yellow (7.5YR 6/6), reddish yellow (7.5YR 7/6), and red (2.5YR 4/6) mottles; dark grayish brown (10YR 4/2), gray (10YR 6/1), reddish yellow (7.5YR 6/6), strong brown (7.5YR 5/8) and red (2.5YR 4/6) mottles, moist; few fine roots in cracks; 10 percent clay films in cracks of bedrock; extremely acid (pH 4.0); gradual wavy boundary. Lab sample # 97P00420
TYPE LOCATION: Amador County, California, about 1.25 miles SE of Buena Vista on Buena Vista Rd; 630 meters NNW of the SE corner of sec. 17, T. 5 N., R. 10 E., MDB&M; WGS84 38.285455 latitude and -120.893521 longitude; UTM zone 10 684234 meters E 4239586 meters N NAD83.
RANGE IN CHARACTERISTICS:
Soil temperature: The mean annual soil temperature at 50 cm depth is 15 to 17 degrees. The difference between mean summer and mean winter soil temperature is greater than 6 degrees C. The soils have a thermic temperature regime.
Soil moisture: The Firebrick soils have a xeric soil moisture regime. The soil moisture control section is dry in all parts from about June to October (about 120 days).
Diagnostic Feature(s):
Ochric epipedon thickness: 8 to 18 cm
Depth to abrupt textural change: 10 to 50 cm
Argillic horizon thickness: 20 to 35 cm
Depth to paralithic contact: 25 to 50 cm
Base saturation: less than 35 percent (by sum of cations) at the paralithic contact.
Particle size control section weighted average:
Rock fragments: 0 to 30 percent, with 0 to 30 percent gravel, 0 to 15 percent cobbles
Clay content: 18 to 35 percent
More than 50 percent (by weight) kaolinite in the clay fraction
More than 4 percent iron oxide (by weight)
A horizon
Hue: 5YR
Value: 4 to 6 dry, 3 or 4 moist
Chroma: 2 to 4, dry or moist
Texture: fine sandy loam, sandy loam, loamy fine sand
Clay content: 5 to 18 percent
Rock fragments: 5 to 30 percent sandstone and ironstone nodules
5 to 30 percent gravel
0 to 5 percent cobbles
Reaction: strongly to very strongly acid
Upper Bt horizon
Hue: 5YR
Value: 4 to 6 dry, 3 or 4 moist
Chroma: 3 to 5 dry, 4 to 6 moist
Texture: loam, fine sandy loam, sandy loam
Clay content: 10 to 20 percent
Rock fragments: 0 to 30 percent sandstone
0 to 30 percent gravel
0 to 5 percent cobbles
Reaction: strongly to very strongly acid
Lower Bt horizon
Hue: 2.5YR, 5YR, 7.5YR
Value: 5 to 7 dry, 3 to 5 moist
Chroma: 3 to 6 dry, 5 to 8 moist
Texture: clay, sandy clay, sandy clay loam
Clay content: 27 to 60 percent
Rock fragments: 0 to 30 percent sandstone
0 to 30 percent gravel
0 to 5 percent cobbles
Reaction: very strongly to extremely acid
Some pedons have a densic contact above the paralithic contact with a top depth ranging from 15 to 25 cm and a thickness of 5 to 20 cm. These densic materials are like the paralithic materials except when air-dried and soaked, they slake.
COMPETING SERIES: There are no other series in this family at this time.
GEOGRAPHIC SETTING: The Firebrick soils are on hills. Slopes range from 1 to 30 percent. These soils formed in residuum from sandstone of the Ione Formation. Elevation is 50 to 235 meters. The climate is Mediterranean with warm, dry summers and cool, moist winters. The mean annual precipitation is 420 to 610 mm and the mean annual air temperature is 16 to 17 degrees C. The frost-free season is 320 to 355 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Mokelumne soils. The Mokelumne soils are on footslopes of hills and are moderately deep to paralithic contact.
DRAINAGE AND PERMEABILITY: Well drained, moderately low saturated hydraulic conductivity.
USE AND VEGETATION: This soil is used for recreation, wildlife habitat, and watershed. Vegetation is chamise, manzanita, yerba santa, gray pine, and annual grasses and forbs.
DISTRIBUTION AND EXTENT: Sierra Nevada Foothills of California; MLRA 18. These soils are of small extent.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Amador County, California, 2025. Firebrick is a placename near the series type location.
REMARKS:
Particle Size Control Section for this pedon: 10 to 38 cm
Diagnostic horizons and features recognized in this pedon are:
Ochric Epipedon 0 to 10 cm
Abrupt Textural Change 28 cm
Argillic Horizon 10 to 38 cm
Paralithic Contact 38 cm
Paralithic Materials 38 to 75 cm
This pedon has an abrupt textural change within the particle size control section that would qualify as "loamy over clayey," but there is no strongly contrasting particle size class for this combination.
Clay mineralogy qualifies as "kaolinitic," but this does not apply to particle size families other than clayey or fine, so mineralogy is "mixed".
The underlying sandstone bedrock has evidence of being deeply weathered with paralithic materials greater than 25 cm thick below the paralithic contact.
ADDITIONAL DATA:
Lab Pedon #: 97P0069
NASIS User Pedon ID: 96CA005005
Soil classified using the 13th Edition of the Keys to Soil Taxonomy.
National Cooperative Soil Survey
U.S.A.