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<br />All azeas of this unit except small areas of deep soil in drainageways are unsuited for use <br />as septic tank absorption fields. The fractures of the interbedded limestone and shale under these <br />soils conduct unfiltered effluent down toward ground water and also downslope. This can result <br />in contamination of ground water and lower areas. <br />Areas of this until where slop is grater than about 15 percent are poorly suited to home <br />site development. <br />This map unit is in capability subclasses IVe, irrigated, and Vie, non-irrigated. It is 50 <br />percent Limestone Breaks #58 range site and 50 percent Loamy Plains #6 range site. <br />84--Penrose-Rock outcrop complex, 25 to 40 percent slopes. This map unit is on steep to <br />very steep ridges, hogbacks, breaks, and canyon sides. The native vegetation is mainly pinyon <br />and juniper. Elevation is 5,100 to 6,000 feet. The average annual precipitation is 11 to 14 <br />inches, the average annual air temperature is 50 to 53 degrees F, and the average frost-free period <br />is 145 days to 165 days. <br />This unit is about 60 percent Penrose soils and about 30 percent Rock outcrop. The <br />components of this unit aze so intricately intermingled in most areas that it was not practical to <br />map them separately at the scale used. Extremely steep to vertical azeas are mainly Rock <br />outcrop, and Penrose soils aze mainly on slopes of 40 percent or less. <br />Included in this unit is about 5 percent Minnequa silt loam on side slopes, swales, and on <br />foot slopes. The Minnequa soil is moderately deep. Also included is about 5 percent Shingles <br />loam on ridges and breaks. Shingle soils have soft bedrock but lack hard bedrock within a depth <br />of 20 inches. In a few azeas moderately deep, clayey Gaynor silty clay loam is included on lower <br />swales and tow slopes. <br />The Penrose soil is shallow and well drained. It formed in residuum derived dominantly <br />from limestone. Slope is 25 to 40 percent. Typically, the surface layer is light brownish gray <br />channery loam about 4 inches thick. The substratum is channery loam about 11 inches thick over <br />hard limestone bedrock at a depth of 15 inches. The soil is moderately alkaline. <br />Petmeability of the Penrose soil is moderate. Available water capacity is very low. <br />Effective rooting depth is 10 to 20 inches. Runoff is very rapid, and the hazard of water erosion <br />is very high. <br />Rock outcrop consists of interbeddded limestone and shale. It is mainly in the form of <br />ledges and cliffs 1 to 30 feet high. Only the top surface of the bedrock strata is exposed, <br />however, on many areas of pediments and ridges. Slop is 25 to 200 percent. <br />This unit is used for rangeland. <br />The potential plan community on this unit is mainly sideoats grams, blue grams, Scribner <br />needlegrass, Indian ricegrass, and a scattered to open stand of one-seed or Rocky Mountain <br />juniper. The average annual production of air-dry vegetation is about 600 pounds per acre. If the <br />condition of the range deteriorates, juniper, unpalatable fortis such as frank bush, red threeawn, <br />and pricklypear increase. <br />This unit is poorly suited to homesite development. The main limitation aze steepness of <br />slope and shall depth to bedrock. <br />This map unit is in capability subclass Vlls, non-imgated. It is in the Limestone Breaks <br />#58 range site. <br />