LOCATION EXFO                    OR

Established Series
Rev. SCW/TDT
01/2023

EXFO SERIES

The Exfo series consist of very shallow, somewhat excessively well drained soils that formed in material weathered from massive, exfoliated Miocene Picture Gorge Basalt. They are on sideslopes and associated with horizontal layers of exposed basalt. Slopes are 2 to 90 percent. The mean annual precipitation is about 12 inches, and the mean annual temperature is about 50 degrees F.

TAXONOMIC CLASS: Sandy-skeletal, mixed, mesic Lithic Torriorthents

TYPICAL PEDON: Exfo very cobbly loamy coarse sand - rangeland, on a 50 percent slope at an elevation of 2,300 feet. (When described on September 13, 1999, the soil was dry throughout. Colors are for moist soils unless otherwise noted.)

A--0 to 5 inches; dark brown (10YR 3/3) very cobbly loamy coarse sand, brown (10YR 5/3) dry; single grain; loose, nonsticky and nonplastic; few very fine roots; few very fine irregular pores; 20 percent cobbles, 15 percent coarse gravels, and 15 percent fine gravel; moderately alkaline (pH 8.1); abrupt wavy boundary. (1 to 8 inches thick)

R--5 inches; dark colored, massive, exfoliated basalt

TYPE LOCATION: Grant County, Oregon, located about 4 miles north of the junction of Highways 19 and 26 or 15 miles south of the community of Kimberly; 1,600 feet east and 1,600 feet north of the SW corner of section 30, T. 11 S., R. 26 E. (Latitude 44 degrees, 34 minutes, and 57 seconds N. and Longitude 119 degrees, 38 minutes, and 49 seconds W.)

RANGE IN CHARACTERISTICS: The soil is dry in all parts for more than to three-fourths of the time when the soil temperature is 41 degrees F. or more. The mean annual soil temperature is 47 to 54 degrees F. Depth to bedrock is 1 to 8 inches but is typically 4 to 6 inches.

The A horizon has chroma of 2 to 4 moist and dry and value of 2 or 3 moist and 4 or 5 dry. It is loamy coarse sand with 5 to 10 percent clay. It has 10 to 20 percent cobbles and 5 to 15 percent coarse gravel derived from fractured, Picture Gorge Basalt and 15 to 35 percent fine gravel formed in place from exfoliated, basalt. Organic matter is 0.5 to 1.0 percent.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Exfo soils are on side slopes and associated with horizontal layers exposed basalt. Slopes are 2 to 90 percent. These soils formed in material weathered from massive, exfoliated Miocene Picture Gorge Basalt. Elevation is 1,400 to 4,800 feet. The climate is semi-arid with cool, moist winters and hot, dry summers. The mean annual precipitation is 9 to 16 inches, and the mean annual temperature is 45 to 52 degrees F. The frost-free period is 90 to 140 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Brisbois, Drinkwater, Gooserock, Haystack, Lickskillet and Ninetysix soils. Brisbois soils are on steep slopes near Badlands, clayey family, and are formed over weathered tuff. Drinkwater, Gooserock, Haystack and Ninetysix soils are all loamy-skeletal and are very deep to bedrock. Drinkwater and Lickskillet soils are on south slopes. Gooserock soils are on north slopes. Haystack soils are on alluvial fans. Lickskillet soils have a mollic epipedon and are 12 to 20 inches to bedrock.

DRAINAGE AND PERMEABILITY: Somewhat excessively drained. Rapid permeability

USE AND VEGETATION: These soils are used for livestock grazing and wildlife habitat. The potential native vegetation is purple sage and curlleaf mountainmahogany.

DISTRIBUTION AND EXTENT: East-central Oregon; MLRA B-10. This series is moderately extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: John Day Fossil Beds National Monument, Oregon, 2000.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon
Aridic moisture regime
Particle size control section - from 0 to 5 inches

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National Cooperative Soil Survey
U.S.A.