LOCATION FRENCHMILL MO

Established Series
Rev. KEB/MLC/RLT
12/2021

FRENCHMILL SERIES

The Frenchmill series consists of very deep, well drained soils that formed in colluvial materials weathered from acid igneous rocks. These soils are on mid and lower back slopes and foot slopes of mountain ridges. Slopes range from 8 to 60 percent. The mean annual temperature is about 56 degrees F., and the mean annual precipitation is about 40 inches.

TAXONOMIC CLASS: Loamy-skeletal, mixed, active, mesic Typic Paleudults

TYPICAL PEDON: Frenchmill very cobbly silt loam - on a backslope of a ridge with 20 percent slope at an elevation of 875 feet in hardwood forest. (Colors are for moist soil unless otherwise stated.)

Oi--0 to 1 inches; slightly decomposed leaf litter and duff.

A--1 to 5 inches; brown (10YR 4/3) very cobbly silt loam, pale brown (10YR 6/3) dry; moderate very fine granular structure; very friable; many very fine to medium roots; undecomposed leaf litter and duff 1 inch thick above the surface; 15 percent rhyolite cobbles and 23 percent rhyolite gravel; extremely acid (pH 4.4); abrupt wavy boundary. (2 to 5 inches thick)

E1--5 to 11 inches; yellowish brown (10YR 5/4) very cobbly loam, light gray (10YR 7/2) dry; weak fine granular structure; friable; many very fine to medium roots; 20 percent rhyolite cobbles and 15 percent rhyolite gravel; very strongly acid (pH 4.8); clear wavy boundary.

E2--11 to 16 inches; dark yellowish brown (10YR 4/6) very cobbly loam, very pale brown (10YR 7/4) dry; weak fine granular structure; friable; common very fine to medium roots; few brown (10YR 5/3) silt coats on rock fragments; 20 percent rhyolite cobbles and 20 percent rhyolite gravel; very strongly acid (pH 4.9); clear wavy boundary. (combined thickness of the E horizon is 5 to 16 inches)

2Bt1--16 to 23 inches; yellowish brown (10YR 5/8) very cobbly loam; moderate very fine subangular blocky structure; friable; common fine and medium roots; common distinct strong brown (7.5YR 4/6) clay films on faces of peds and few silt coats; 20 percent rhyolite cobbles and 25 percent rhyolite gravel; very strongly acid (pH 4.8); clear wavy boundary. (6 to 50 inches thick)

2Bt2--23 to 31 inches; yellowish brown (10YR 5/6) extremely gravelly loam; moderate fine subangular blocky structure; firm; few fine and medium roots; common yellowish red (5YR 4/6) clay films on faces of peds and common light yellowish brown (10YR 6/4) silt coats; 18 percent rhyolite cobbles and 42 percent rhyolite gravel; very strongly acid (pH 4.8); gradual wavy boundary.

2Bt3--31 to 37 inches; 60 percent strong brown (7.5YR 4/6) and 40 percent light yellowish brown (10YR 6/4) very gravelly loam; moderate fine subangular blocky structure; firm; few fine roots; many prominent dark red (2.5YR 3/6) clay films on faces of peds; 15 percent rhyolite cobbles and 37 percent rhyolite gravel; very strongly acid (pH 4.7); clear wavy boundary. (combined thickness of the 2Bt horizon is 0 to 36 inches)

3Bt4--37 to 47 inches; strong brown (7.5YR 5/8) sandy clay loam; weak fine and medium subangular blocky structure; firm; few very fine roots; few prominent light reddish brown (5YR 6/3) clay films on vertical faces of peds and common prominent yellowish red (5YR 4/6) clay films on faces of peds; very strongly acid (pH 4.7); clear wavy boundary.

3Bt5--47 to 55 inches; strong brown (7.5YR 4/6) sandy clay loam; moderate coarse prismatic structure; firm; few very fine roots; few prominent reddish gray (5YR 5/2) clay films on faces of peds and common prominent yellowish red (5YR 4/6) clay films on faces of peds; very strongly acid (pH 4.8); gradual wavy boundary.

3Bt6--55 to 71 inches; 60 percent strong brown (7.5YR 5/8) and 35 percent yellowish red (5YR 5/6) sandy clay loam; weak coarse prismatic structure; friable; few prominent pinkish gray (5YR 6/2) clay films on vertical faces of peds and few prominent pinkish gray (5YR 7/2) clay films on vertical faces of peds; 1 percent rhyolite gravel; very strongly acid (pH 4.9).

TYPE LOCATION: Madison County, Missouri; about 9 miles west of Fredericktown; 125 feet south and 1350 feet east of the NW corner of section 3, T. 33 N., R. 5 E.; Rhodes Mountain USGS quadrangle; latitude 37 degrees 35 minutes 54 seconds N. and longitude 90 degrees 29 minutes 9 seconds W.

RANGE IN CHARACTERISTICS:

A horizon
Hue: 10YR
Value: 3 to 5 (6 dry)
Chroma: 2 or 3
Fine Earth: silt loam
Rock fragments: 0 to 50 percent cobbles and 0 to 40 percent gravel
Reaction: very strongly acid to moderately acid

E horizon
Hue: 10YR or 7.5YR
Value: 4 to 6
Chroma: 3 to 6
Fine Earth: silt loam or loam
Rock fragments: 0 to 20 percent cobbles and 0 to 55 percent gravel
Reaction: very strongly acid or strongly acid

Bt horizon (where present)
Hue: 10YR to 5YR
Value: 4 to 6
Chroma: 3 to 8
Fine Earth: silt loam, loam
Rock fragments: 0 to 20 percent cobbles, 5 to 50 percent gravel, and 0 to 20 percent stones
Reaction: very strongly acid or strongly acid

2Bt horizon
Hue: 10YR to 2.5YR
Value: 4 to 7
Chroma: 3 to 8
Fine Earth: loam, clay loam, silty clay loam, silt loam
Rock fragments: 0 to 40 percent cobbles and 5 to 50 percent gravel, 0 to 15 percent stones
Reaction: extremely acid to strongly acid

3Bt horizon
Hue: 10YR to 2.5YR
Value: 3 to 6
Chroma: 4 to 8
Fine Earth: sandy clay loam, clay loam, clay
Rock fragments: 0 to 20 percent cobbles and 0 to 40 percent gravel
Reaction: extremely acid to strongly acid

COMPETING SERIES: This is the Downsville series. Downsville soils have a mean annual temperature of 50 to 54 degrees F., and formed in alluvium on terraces.

GEOGRAPHIC SETTING: Frenchmill soils are on mid and lower back slopes and footslopes of mountain ridges. Typically these soils have deeply entrenched drainageways. These soils formed in colluvial materials weathered from acid igneous rocks. Slopes range from 8 to 60 percent. The mean annual temperature is ranges from 54 to 58 degrees F. and the mean annual precipitation ranges from 35 to 45 inches.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Delassus, Hassler, Irondale, Killarney, Knobtop, Skranka, Taumsauk, Tilk, and Trackler soils. Delassus soils have a fragipan, have less than 15 percent rock fragments, and are on less sloping ridgetops and shoulder slopes above the Frenchmill soils. Hassler soils are moderately deep and are on less sloping ridgetops, sideslopes and benches. Irondale and Knobtop soils are moderately deep to bedrock and are on side slopes and ridgetops above Frenchmill soils. Killarney soils have a fragipan and are on similar landscape positions. Skranka soils are in the fine textural family, and are in basins. Taumsauk soils are less than 20 inches to bedrock and are on sideslopes above Frenchmill soils. Tilk soils have a higher base saturation, and are on flood plains. Trackler soils are deep to bedrock, have less than 35 percent rock fragments and are on ridgetops and shoulder slopes above the Frenchmill soils.

DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium to high. Permeability is moderate. The saturated hydraulic conductivity is moderately high.

USE AND VEGETATION: Nearly all areas are forested. Native vegetation is mixed hardwoods and shortleaf pine.

DISTRIBUTION AND EXTENT: The St. Francois Mountains of the Missouri Ozarks (MLRA 116C). The series is of moderate extent.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: INDIANAPOLIS, INDIANA

SERIES ESTABLISHED: Madison County, Missouri, 1998.

REMARKS: Diagnostic horizons and features recognized in this series are:
Ochric epipedon - the zone from the surface of the soil to a depth of 16 inches (Oi, A and E horizons)
Argillic horizon - the zone from 16 to 71 inches (2Bt and 3Bt horizons)

ADDITIONAL DATA: University of Missouri soil characterization laboratory number M9312311; NSSL number S93MO123011.

These soils were previously included in the Killarney series in mapping.

National Cooperative Soil Survey
U.S.A.