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~ 00 C"": - PRmECT LANDS c Soils The most extensive arable areas of the project are Fort Lewis Mesa and Red Mesa.' They consist of reddish fine sandy loams to silt loams, aeolian in origin or modified by wind action in the surfaces, and are generally underlaid at depths of four feet or more by gravel, which forms a mantle covering the sandstone and shale substrata in the area. These soils are well drained, yet have a good water-holding capacity and are inherently fertile. The soils of the bottom lands have developed from recent alluVial deposits. In Thompson Park and along Cherry Creek the soils consist of deep silt loams to clay loams and are slightly less desirable for development than the mesa soils, but nevertheless well adapted to irri- gation agriculture. Soils along La Plata River are coarser-textured sediments--largely sands and.gravels--and in only a few small areas are these soils of sufficient depth over gravel to be satisfactory for irrigation. The soils in New Mexico are alluvial in origin. The terrace soils consist of brown fine sandy loams'to silt loams with a depth of about four feet over gravel, shale, or sandstone. In general, they are of excellent quality for irrigation, having good drainage, a relatively high fertility, and a good water-holding capacity. The bottom land soils adjacent to the channel of La Plata River are sl1glitly heavier textured than the terrace soils. The soils of the project are relatively free of harmful concentra- tions of soluble salts, though, in general, the soils in New Mexico con~ tain larger amounts than those in Colorado. TOPQRraphy ,and Draina~e For the most part, topography is favorable for irrigation practice. On Fort Lewis and Red Mesa, the lands are concentrated in a large com~ pact area with a uniform gentle slope. The bottom lands in Thompson Park and Hay Gulch slope steeply but they comprise relatively smooth continuous tracts that are favorable for irrigation. Similar features identify the lands in New Mexico. Soils and topographic conditions on most of the project lands are inducive to good surface and internal drainage under irrigation develop- ment. Some seepage is evident near the lower end of the terrane in New Mexic 0, where some artificial drainage would probably be required. The problem is a local one and is not expected to develop extensively. Land Classification A semi-detailed land classification was made of the project area in Colorado in 19~,l to iletenmne the extent and character of the lands and their degree vi" suH,Cl.'bleness for develoJl'llent, based on productive capa- city for genanl crop far:11J.ng under irrigation. The survey involved the delineatio~ of ' the arable lands and segregation of these lands into 17