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in the valleys and relatively level uplands to 50 percent or more along the sideslopes of major drainages. The area is characterized by mild summers and cold winters, and has a low average annual amount of precipitation. Seasonal temperatures can be extreme, ranging from 108°F in the summer to -33°F in the winter. Average summer temperatures range from 95°F in the daytime to 50°F at night. Average winter temperatures are 29°F. Precipitation averages from 8-1/2 to 9 inches annually, with the majority of it occurring in Late :summer and early fall. Average winter snow accumulation is usually less: than 12 inches and generally does not remain on the ground very long. Southern exposures may remain free of snow for most of the year. Th.e growing season is short, usually less than 100 days, and occurs from late Hay to mid-September. The Cretaceous Hesaverde Group in northwestern Colorado has been divided into two formations: the lower Iles Formation and the upper Williams Fork Formation, which are separated by the Trout Creek Sandstone. The Williams Fork Formation is further divided into Upper and Lower members. The Lower Williams Fork Member contains coal seams A through J, of which the B and D seams are or will be recovered within the Deserado Mine LHU. The dip of the Hesaverde Group within the general area is cont.colled by the asymmetric Red Wash Syncline, which strikes northwest-southeast. Dips vary from 1 degrees to the northeast in the southern part of the LHU, to horizontal at the synclinal axis, to as much as 70 degrees to the southwest on the north flank of the syncline. The coal and sandstone beds outcrop along this steep northern flank. Minerals Coal The coal deposits of the Prairie Dog Lease Tract are located in the Lower White River coal Eield, within the late Cretaceous Hesaverde Group. Coal seams of interest occur within the main coal member of the Williams Fork Formation (seams A thru J). Only coal contained in the B and D seams is of adequate thickness to be considered minable. Exploration in the area indicated the presence of splits and partings in both the B and D seams including a major parting in the D seam. The parting in the D seam reduces the minable seam thickness from 8 to 9 1/2 feet to 3 or 4 feet. The location of the parting in the D seam is a physical boundary which limits the recovery of D seam coal in the area. The thin interburden between the D seam •and B seam (less than 10 feet in some areas) would preclude mining in both the B and overlying D seams. The D seam has a higher clean coal reserve potential than does the B seam. Therefore, mining of the D seam is a priority and 8 seam coal is considered nonrecoverable. Oil and Gas All federal oil and gas minerals have been leased in this area. The tract is covered by two oil and gas leases. The leases are C-37363 6