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worked over a moderate range of soil moisture without serious loss of favorable physical properties for seedbeds. Any use of the soils of this unit for materials for new seedbeds probably will be accomplished by a mixture of the A2 and B2t horizons. The result will be a matrix of sandy loam or sandy clay loam in which clods of clay loam are embedded. Such a mixture would have physical properties intermediate between those described for [he two horizons separately and would still be physically capable of being toed as seedbeds. Thc soils of this unit are listed as moderate for use in new seedbeds due to anticipated poor fertility levels rather than physital limitations. The soils of this unit have low shrink/swell ratios, with a difference in volume changing ability between the upper and lower soil horizons. Assuming an upper 20 inches of loam to clay loam, the potential total extensibility of a 40-inch section is about 0.4 to 1.4 inches. Normally the soils of this unit are not subject to serious flood hazards, although streams may flood occasionally. In their natural state, these soils are not susceptible to accelerated sail erosion unless native vegetative cover has been destroyed or depleted. When disturbed and cleared these soils are moderately susceptible to both wind and mater erosion. No tendency toward mass movement was noted within areas mapped as mapping unit number X38 and the potential for such movement is low. Chemical Properties and Natural Fertility -These are moderately weathered, mature soils having genetic horizonation including horizons of silicate clay accumulation, but lacking horizons of calcium carbonate accumulation. Soil reaction ranges from slightly acid to mildly alkaline. Under these conditions the cation • cxchange complex (portion of the soil having the ability to hold and exchange cations) is base saturated or nearly so with calcium being the dominant cation. Thus, there is no deficiency of bases but there is no excess of calcium or magnesium carbonate to depress the availability of other plant nutrients. Detrimental accumulation of sodium or other soluble salt was not observed in these soils. It is characteristic of the type of soil development found in areas of mapping unit number X38 to have thick, strongly weathered and partly leached surface horizons (A2 horizons). These horizons are very light colored due to a lack of organic matter and part of their original content of clay has been removed. The type of vegetative cover (conifer) growing on these soils yields very low annual returns of readily decomposable organic matter and favors acid-forming microbiological life in the organic mulch that overlies the mineral portion of the soil. While these processes are not as advanced as in the Spodosolic soil groups (Podzols), they have exerted some influence on the genesis of the soils of this group. Consequently, natural fertility levels in the upper horizons of the soils of this group are below average for the area. While they are adequate [or present stands of timber and deep root systems, some program of fertilization including potassium, nitrogen, and phosphorus would prove beneficial to revegetation activities involving these soils. Soil analysis indicated a borderline detcienry of potassium in these soils (see F~hibi[ 26). Manoine Unit Number 200; land Tie: Rockland, Sandstone, and Shale -Mapping unit number 200 is a land type in which the soil pattern is extremely variable from area to area. Typically this unit is used to describe the steep and very steeply sloping escarpment-like borders of mesas, but may also occur on the crests and shoulders of ridges and hills. Its soil pattern is the same as That described Cor mapping unit number 1, except that the areas have a significant amount of bare rock outcrop. Rock is usually ledge sandstone but areas of raw shale are included as well. Rock outcrops constitute about 25 to 90 percent of • delineated areas.