Situated at approximately 1,881 m above mean sea level, the site area has a relatively mild climate, in contrast to much of Wyoming. The airport in Cheyenne reports an average annual temperature of 8° C, with the lowest average temperature in January (-3° C) and the highest in July (20° C). The average annual precipitation is 33.76 cm, with the greatest average precipitation occurring in May and June (Martner 1986:310). The average annual snowfall is 125.22 cm, mainly occurring from November through April (Martner 1986:310).

Crow Creek drains from the Laramie Mountains in the west to the South Platte River in Colorado. The combination of riparian and grassland habitat surrounding the drainage is year-round habitat for pronghorn antelope (Figure 3), mule deer, and white-tailed deer (Department of the Air Force [DoAF] 1984:2-32). Bison are not presently found in the area, but their frequent presence in the archeological record documents their importance before historic changes to the area. Small-game species are also abundant and include mourning dove, cottontail rabbit, and fox squirrels. Small numbers of ring-tailed pheasants, bobwhite, and sharp-tailed grouse may also be found. Fish are present in Crow Creek, and suckers, shiners, minnows, darters, and chubs can currently be collected there (DoAF 1984:2-96-2-98). Perch, walleye, and trout are also species typical of waters in the Central Plains.

The site area is covered in mixed-grass prairie and lies adjacent to the riparian environment surrounding Crow Creek (Figure 1). The mixed-grass prairie includes blue grama, buffalo grass, needle-and-thread grass, linear leaved sedge, and copper mallow (Tetra Tech 1987:6-9). Prickly pear and yucca are also present. Along the stream bed, cottonwoods are presently the predominant plant, although they were planted early in the history of the base (Bill Metz, personal communication 1991). Willows are also common along the river and predate historic occupation of the area. Other common riparian plants on the base include cattail, Baltic rush, spike-rush, sedges, scouring rush, slough grass, American manna grass, cordgrass, cow parsnip, dock, clover, death camas, plantain, water smartweed, cinquefoil, and violet (Tetra Tech 1987:6-10-6-11).

The environment seen today at F. E. Warren AFB is the result of relatively recent conditions. Fluctuations in past climatic regimes caused changes in the fauna and flora of the area that affected the way the people utilized their environment. Due to microclimatic differences, the environment at the base would have been affected by these changes in a unique manner, as it is today. However, a climatic chronology specific to the base does not, at present, exist. 

Radiocarbon dates obtained on materials from 48LA277 fall mainly within the Scandic period, a warmer and probably drier time period on the Northern Plains than today's climate. It is possible that the mountains became more important to Plains people during drier time periods. The mountains were cooler and moister and provided both people and game animals relief from the summer heat as well as plant species that may not grow on the Plains.

Charcoal recovered from the cultural features included wood from local riparian species: willow or cottonwood (Salicaceae), birch (Betula), and wild cherry or plum (Prunus) bushes (Appendix B). This suggests that at the time of occupation, these were probably the predominant woody plants available for fuel along Crow Creek near the site. Analysis of phytoliths from feature fill (Appendix C) suggests that a mixed-grass prairie, similar to the present, also existed at the time of occupation.

During 1992, extensive geomorphological investigations were undertaken (Appendix A). For the most part, the underlying soil horizons parallel the existing topography, suggesting that at the time of occupation of 48LA277, the terrace topography was similar to that found today. Fluvial sediments found in Backhoe Trenches 1 and 9 suggest that Crow Creek was located much closer to the site area during the occupation of 48LA277. In fact, the creek may have been as close as 50 m to the southeast of the main site area, as opposed to the 210 m separating the two areas today. Later, the creek was as close as 25 m to the site area. The soil type and the pollen evidence (Appendix B) both suggest that the ground surface was covered with a thick growth of grass. The pollen and macrobotanical evidence suggest that a riparian environment existed along Crow Creek.

A stratigraphic pollen column was taken from Backhoe Trench 1 at 48TE411, and the results of the analysis are reported here by Cummings and Puseman in Appendix B. The pollen diagram is shown in Appendix B, Figure B1. Most of the samples include fairly large amounts of Pinus pollen and traces of Picea and Juniperus. Much of this pollen probably results from long-distance wind transport of the pollen from the mountainous areas to the west. Fluctuations in the pollen in samples from colluvial sediments 150-220 cm below surface (cmbs) in the trench suggest the lack of a stable surface, possibly resulting from the high rate of colluviation after occupation of the site. Fluctuations in pollen quantities between this point and the surface may mainly reflect the changing local vegetation correlated with the changes in the location of Crow Creek.