LOCATION PETREL AK
Established Series
Rev. RWG/DJL/JPM
02/2022
PETREL SERIES
The Petrel series consists of moderately deep to bedrock, poorly drained soils formed in colluvium and residuum from igneous and noncalcareous sedimentary rocks. Petrel soils are on backslopes and footslopes of hills and mountain toeslopes. Slopes range from 5 to 75 percent. Mean annual precipitation is about 112 inches and mean annual temperature is about 45 degrees F.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, acid Aeric Cryaquepts
TYPICAL PEDON: Petrel very fine sandy loam -- on a 40 percent SSW facing slope under conifer forest vegetation, at an elevation of 960 feet. (All colors are for moist soil)
Oi1--7 to 3 inches; undecomposed sphagnum moss and woody material; 90 percent fiber content rubbed and unrubbed. (0 to 4 inches thick)
Oi2--3 to 0 inches; black (N 2/0) partially decomposed plant material; 90 percent fiber content unrubbed and 75 percent fiber content rubbed; many fine and very fine, common coarse and medium roots; abrupt wavy boundary. (0 to 3 inches thick)
B/E--0 to 5 inches; yellowish red (5YR 4/6) very fine sandy loam; weak medium subangular blocky structure; friable, slightly sticky and nonplastic; common medium prominent pinkish gray mottles (5YR 6/2); extremely acid (pH 4.0); clear wavy boundary. (0 to 5 inches thick)
E/B--5 to 10 inches; gray (5YR 6/1) silt loam; massive; friable, slightly sticky and slightly plastic; common medium prominent yellowish red (5YR 5/6) mottles; common medium distinct dark reddish brown (5YR 3/2) organic stains; very strongly acid (pH 4.5); clear wavy boundary. (2 to 10 inches thick)
2C--10 to 27 inches; yellowish brown (10YR 5/6) very gravelly loam; massive; friable; slightly sticky and slightly plastic; 40 percent gravel; very strongly acid (pH 4.5); abrupt wavy boundary. (15 to 25 inches thick)
R--27 inches; sandstone bedrock.
TYPE LOCATION: Ketchikan Area, Alaska, Suemez Island, in the SE 1/4, SE 1/4, Section 1, T.76S., R.79E., Copper River Meridian.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 38 to 42 degrees F. The thickness of the solum ranges from 5 to 15 inches. The depth to bedrock ranges from 20 to 40 inches. The gravel and cobble content in the particle size control section ranges from 35 to 75 percent. Reaction is extremely or very strongly acid in the upper part of the profile but ranges to strongly acid in the lower part.
An A or E horizon is present in some pedons.
The B/E horizon has matrix hue from 5YR to 10YR, value from 2.5 to 4, and chroma from 1 to 6. Texture is very fine sandy loam or silt loam. Coarse fragment content includes 0 to 25 percent cobble and 0 to 10 percent gravel.
The E/B horizon has matrix hue from 5YR to 10YR, value from 4 to 6, and chroma of 1 or 2. Mottles have hue from 5YR to 10YR, value from 2.5 to 5, and chroma from 1 through 8. Texture is very fine sandy loam or silt loam. Coarse fragment content includes 0 to 25 percent cobble and 0 to 10 percent gravel.
A BC horizon is present in some pedons.
The C and 2C horizons have hue ranging from 10YR to 5GY, value from 4 to 6, and chroma from 1 to 6. Texture is loam or fine sandy loam with 35 to 75 percent coarse fragments, including 5 to 40 percent cobble and 30 to 60 percent gravel.
COMPETING SERIES: There are no competing series in the same family.
GEOGRAPHIC SETTING: The Petrel soils are on backslopes and footslopes of rolling hills and infrequently dissected mountain sideslopes. Petrel soils formed in colluvium and residuum derived from igneous and noncalcareous detrital sedimentary rocks, and are underlain by these rocks at depths of 20 to 40 inches. The climate is humid maritime with mean annual precipitation of 112 inches. The mean annual temperature is about 45 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the
Kina,
Maybeso,
Remedios,
Tolstoi, and
Wadleigh soils. Kina and Maybeso soils are organic soils on hillslopes. Tolstoi soils are shallow, well drained soils on backslopes of mountains and hills. Wadleigh soils are formed in glacial till and are on backslopes and footslopes of hills. Remedios soils are deep, well drained soils on footslopes and toeslopes.
DRAINAGE AND PERMEABILITY: Poorly drained. Moderate permeability in the solum and moderately rapid in the skeletal substratum. Runoff is slow on the gentle slopes and medium to rapid on the steeper slopes.
USE AND VEGETATION: The Petrel soils are used for timber production, watershed protection, wildlife habitat, and recreation. The climax forest overstory vegetation is dominantly western hemlock, with lesser amounts of Sitka spruce and Alaska cedar. The understory vegetation is dominantly blueberry and huckleberry species, deer cabbage, yellow skunkcabbage, fernleaf goldthread, and heartleaf twayblade.
DISTRIBUTION AND EXTENT: Southeast Alaska. The series is of minor extent.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: WASILLA, ALASKA
SERIES ESTABLISHED: Ketchikan Area, Alaska. 1994.
REMARKS: Diagnostic horizons and features in this soil are:
a.cambic horizon; loamy-skeletal material from 10 to 27 inches; a subhorizon with mottles and matrix chroma of 2 or less within 20 inches of the surface; a cryic temperature regime. The soils are named after Petrel Island. A cobbly surface phase is recognized in mapping.
National Cooperative Soil Survey
U.S.A.