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16
<br />• 801E BURVEY
<br />cent. Leaps and Morop soils make
<br />of some mapped areas.
<br />This soil is used mostly for graz EXHIBIT D-3
<br />used for irrigated hay and pastor,
<br />to rapid, and the erosion hazard is
<br />Capability units VIe-1 irrigated, Vlle-1 nonlrrtgatea;
<br />Deep Clay Loam range site.
<br />Duffson Series
<br />The Duffson series consists of moderately deep, well-
<br />drained, calcareous soils on hills, ridges, and benches.
<br />Slopes are 5 to 90 percent. These soils formed in locally
<br />transported alluvium that was derived from calcareous,
<br />interbedded sandstone and shale.
<br />In a representative profile. the surface layer is gray-
<br />ish-brown loam about 5 inches thick. The subsoil is
<br />brown and light yellowish-brown loam and clay loam
<br />about 1.5 inches thick. It is calcareous in the lower part.
<br />The substratum is about ]0 inches of strongly calcar-
<br />eous, white loam. Below this is sandstone bedrock.
<br />Duffson soils are at elevations of 7,100 to 9,500 feet.
<br />The average annual soil temperature is 45° F. The aver-
<br />age soil temperature in summer is 62°. The average
<br />annual precipitation is 17 inches. The vegetation is
<br />commonly big sagebrush, Arizona fescue, wheatgrass,
<br />and native bluegrass.
<br />Permeability is moderately slow. The root zone is
<br />only 20 to 90 inches deep, and available water capacity
<br />is low•.
<br />Most of the acreage is used for grazing.
<br />The Duffson soils in the Gunnison Area are mapped
<br />only with Corpening and Spring Creek soils.
<br />Representative profile oC Duffson loam, 5 to 35 per-
<br />cent slopes; N~V7 i 4 sec. 35, T. 48 N., R. 2 E., Saguache
<br />County
<br />A]-0 to 5 inches, grayish-brown (lOYR 5/2) light loam,
<br />very dark grayish brown (]OYR 3!2) moist; mod-
<br />erate, very fine, granular structure; soft, very
<br />friable; 10 percent fine sandstone gravel; pH 6.8;
<br />cleat, smooth boundary.
<br />Blt-5 Lo 8 inches, brown (7.5YR 5/3) day loam, dark
<br />brown (i.SYR 3/3) moist; weak, medium, sub-
<br />angular blocky structure parting to moderate, very
<br />fine, subangular blocky; slightly hard, eery friable;
<br />thin patchy clay films on ped faces; about 10 Der-
<br />cent fine sandstone gravel; pH fi.8; clear, smoc,th
<br />boundary.
<br />B2t-8 to 10 inches, brown (7.SYR 5/3) clay loam, dark
<br />brown (7.5YR 4/3) moist; weak, medium, pris-
<br />matic structure parting to moderate, medium, sub-
<br />angular blocky; hard, friable: thin nearly con-
<br />tinuous clay films on ped faces; about ]0 Dement
<br />angular sandstone gravel; pH 7.0: Blear, wavy
<br />boundary.
<br />B3tca-16 to 20 inches, light yellowish-brown (10YR 0/4)
<br />heary loam, yellowish hmw•n (lOS"B 5/4) nmist:
<br />weak, medium. subnngular bfocky structure; hard.
<br />friable; few, thin, patchy clay film mr ped fans;
<br />10 percent angular sand=tone gravel; lime in fine
<br />seams and small concretions; pH R.n; gradual, wavy
<br />boundary.
<br />Cce-20 to 30 inches, white (lOYR 8/21 loam, light gray
<br />(lOYR 7/2) nroict; massive: hard, friable; ebost
<br />10 percent sandstone gravel; celenrrous; marl-like
<br />lime coatings on stone fragments; pH 8.2; clear,
<br />smooth boundary.
<br />R-30 inches, sandstone.
<br />The A horizon is t]'Pically loam, but in places is fine sandy
<br />loam. If is 4 to 9 inches thick and is grayish brown or brown.
<br />Yes from 20 W ~0 inches. The content
<br />a b to 1b yercent
<br />( 1 2 Pages ) dams; 5 l0 35 percent slopes (DrEI.
<br />s mainly in the central part of the
<br />est acreage is between Razor and
<br />i,ocnetopa t,reess. i he unit is about 50 percent Duffson
<br />loam and 30 percent Corpening loam. The Duffson soil
<br />is generally on northern and eastern exposures. The
<br />Corpening soil is commonly on windswept, southern and
<br />western exposures. In some eroded areas of these soils,
<br />the surface laver is thinner and stonier than that in
<br />the profiles described as representative of the series.
<br />Included with these soils in mapping are small areas
<br />of Lucky and Partin soils, areas of severely eroded Duff-
<br />son and Corpening soils, and areas of Rock outcrop and
<br />Stonv rock land. Also included are areas of Alluvial
<br />land and Alluvial land, wet, commonly along small drain-
<br />agew•ays and tce slopes. Included soils make up less than
<br />20 percent of the total acreage.
<br />This unit is almost entirely in range. Runoff is me-
<br />dium. The erosion hazard is moderate unless a goad
<br />plant cover is maintained. Capability unit VIe-5 non-
<br />irrigated; Duffson soil in 11lountain Loam range site,
<br />Corpening snit in Dry Mountain Loam range rte.--
<br />con-Spring Creek stony loams, 5 l0 40 percent
<br />vl nQC 1DsE~ Thic mannint 't ' I n
<br />central part of the survey area. It is about 65 percent
<br />Duffson stun}' Inam and 20 percent Spring Creek stony
<br />loam. The Duffson soil is mainly on northern exposures.
<br />At the higher elevations it has a surface layer 10 to 20
<br />inches thick. The Spring Creek soil is on windswept,
<br />southern and western exposures. Tt has the profile de-
<br />scribed as representative of the Spring Creek series.
<br />Slopes are complex.
<br />Included with these soils in mapping are small areas
<br />of Mord and Par•lin soils and areas of Alluvial ]and and
<br />Alluvial land, wet, almlg minor drainageways in nar-
<br />row, winding valleys. Also included are areas of Rock
<br />outcrop and Stone rock land on the steeper slopes and
<br />a few' small sandy areas of wind-deposited material nn
<br />north-facing slolses near Gunnison. Lrcluded soils make
<br />up 15 percent of the total acreage.
<br />A'early all the acreage is in native vegetation and is
<br />used for range, recreatimt, and wildlife. Runoff is me-
<br />dium to rapid, and the erosion hazard is moderate to
<br />high. About half the acreage, particulark where vege-
<br />tation is spare. has been eroded by wind and wader.
<br />Tn these areas the surface lacer is thinner and stonier
<br />than is typical. lu some areas up to 3 acres in size, the
<br />Spring Creek soil has been so severely eroded that bed-
<br />rock is expmed. Capability unit Vtls-1 nnnirrigated:
<br />Duffson soil in \1nuntain Loam range site, Spring ('reek
<br />sail in Dn' Dinunt:rin Inam range site.
<br />Evanston Series
<br />The Evanston series consists of deep, well-drained
<br />soils on alluvial fans and valley-fill slopes. Slopes are
<br />I to 2U percent. These soils formed in alluvium that was
<br />derieed from sandstone, rhyolite, and tuft.
<br />In a representative profile the surface layer is dark-
<br />brown loam about 6 inches thick. The subsoil is brown
<br />clay loam and Inam atx,ut 12 inches thick. it ie calcare-
<br />
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