LOCATION PERIL AK
Established Series
Rev.CSC/JMD/JPM
02/2022
PERIL SERIES
The Peril series consists of shallow to bedrock, somewhat poorly drained soils formed in colluvium and residuum on mountain and hill sideslopes. Slopes range from 50 to 75 percent. Mean annual precipitation is in excess of 60 inches and the mean annual temperature is about 46 degrees F.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Lithic Humicryods
TYPICAL PEDON: Peril silt loam - on a west facing straight slope of 60 percent at 860 feet elevation under conifer forest vegetation. (All colors are for moist soil)
Oi -- 3 to 2 inches; forest litter and living mosses; many fine and medium, and common coarse roots. (0 to 2 inches thick)
Oa -- 2 to 0 inches; muck; many fine and medium, and common coarse roots; extremely acid (pH 4.0); gradual smooth boundary. (1 to 4 inches thick)
A -- 0 to 5 inches; very dark brown (10YR 2/2) silt loam; weak fine subangular blocky structure; friable; 5 percent gravel; many fine and medium, and few coarse roots; extremely acid (pH 4.0); abrupt smooth boundary. (0 to 5 inches thick)
E -- 5 to 6 inches; dark grayish brown (10YR 4/2) silt loam; weak fine subangular blocky structure; friable; 5 percent gravel; common fine and medium roots; very strongly acid (pH 4.5); abrupt smooth boundary. (1 to 2 inches thick)
Bhs -- 6 to 10 inches; dark brown (7.5YR 3/2) gravelly silt loam; weak fine subangular blocky structure; friable; distinct very dark brown (10YR 2/2) mottles in the lower horizon; 25 percent gravel; common fine and medium roots; very strongly acid (pH 5.0); abrupt smooth boundary. (3 to 6 inches thick)
Cl -- 10 to 14 inches; olive brown (2.5Y 4/3) very gravelly silt loam; weak fine subangular blocky structure; friable; prominent black (5Y 2.5/2) mottles; 50 percent gravel; common fine and medium coarse roots; very strongly acid (pH 5.0); gradual smooth boundary. (2 to 7 inches thick)
C2 -- 14 to 17 inches; olive brown (2.5Y 4/3) very gravelly silt loam; massive; friable; faint dark grayish brown (10YR 4/2) mottles; 60 percent gravel; few fine roots; strongly acid (pH 5.5); gradual irregular boundary. (0 to 3 inches thick)
R -- 17 inches; medisedimentary rock.
TYPE LOCATION: Point Adolphus, Chatham Area, Alaska. SW1/4, SE1/4, Sec. 11, T.42S., R.58E., Copper River Meridian.
RANGE OF CHARACTERISTICS: MAST ranges from 38 to 42 degrees F. The thickness of the solum ranges from 6 to 13 inches. Depth to bedrock ranges from 14 to 20 inches. The weighted average particle size of the control section has less than 18 percent clay and more than 15 percent fine sand or coarser. Coarse fragment content in the control section ranges from 50 to 80 percent gravel. Reaction increases with depth, ranging from extremely acid to slightly acid.
The combined thickness of the O horizons ranges from 2 to 6 inches.
The E horizon has hue of 7.5YR or 10YR, value of 4 or 5 and chroma from 2 to 4. Coarse fragment content ranges from 5 to 20 percent gravel.
A Bh horizon is present in some pedons.
The Bhs horizon has hue from 5YR to 10YR, value and chroma of 2 or 3. Coarse fragment content ranges from 25 to 80 percent. Distinct and prominent mottles are commonly present in the lower part of the horizon.
A mottled Bs horizon is present in some soils
The C horizon has hue from 7.5YR to 2.5Y, value from 3 to 5 and chroma of 2 or 3. Coarse fragment content ranges from 50 to 80 percent. Prominent mottles are commonly present.
COMPETING SERIES: These are the
Hannegan (WA),
Mosman (AK),
Naukati (AK), and
Tolstoi (AK) series in the same family. Hannegan soils have volcanic ash throughout the profile. Mosman soils have bedrock within 14 inches. Naukati and Tolstoi soils lack mottles within the spodic horizon.
GEOGRAPHIC SETTING: The Peril soils are on mountain slopes and hill slopes and are formed in residuum and colluvium of mixed minerology. Peril soils overlie bedrock within 20 inches depth. The climate is humid maritime with a mean annual precipitation range of 60 to 220 inches. The mean annual temperature is about 46 degrees F. and the mean summer temperature is about 57 degrees F. Elevation ranges from 0 to 3000 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Kupreanof and
Tolstoi soils on similar landforms. Kupreanof and Tolstoi soils are both well drained. Kupreanof soils are also deeper than 40 inches over bedrock.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained. Moderate permeability. Runoff is very slow.
USE AND VEGETATION: The Peril soils are used for timber production, watershed protection, wildlife habitat and recreation. The overstory is dominantly western hemlock. The understory is dominantly blueberry with some rusty menziesia.
DISTRIBUTION AND EXTENT: Southeast Alaska. The series is of minor extent.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: WASILLA, ALASKA
SERIES ESTABLISHED: Chatham Area, Tongass National Forest, Alaska, 1992.
REMARKS: Diagnostic horizons and features recognized in this soil include: an albic horizon from 5 to 6 inches; a spodic horizon from 6 to 10 inches with assumed organic carbon content greater than 6 percent; cryic temperature regime; bedrock at 17 inches; weighted average particle size of loamy-skeletal from 10 to 17 inches.
This series could classify as a Typic Cryaquod under the 1991 revised Spodosol criteria. This soil, however, does not exhibit the saturated conditions typical of an Aquod which is reflected in the forest productivity. Redoximorphic features are present lower in the spodic horizon and the soil exhibits characteristics of somewhat poor drainage. It is assumed the soil is not saturated to the surface nor does the capillary fringe extend to the surface during the year.
ADDITIONAL DATA: Laboratory data is available on this soil: NSSL Number 84P0117.
National Cooperative Soil Survey
U.S.A.