90 SMITHSONIAN INSTITUTION 



archeological stratum in the banks of a deep ravine that traverses 

 part of the old valley bottom (fig. 93). Exposure of the former sur- 

 face of occupation started from the side of a test trench dug in 1938 

 and continued up, down, and along the slope (fig. 94). The layers 

 of earth in the overlying deposits at this part of the site hold so con- 

 sistent a level in relation to the course of the old valley and have 

 such a gradual slant in the other direction that a narrow trench was 

 cut through from the main excavation to the edge of the terrace to 

 ascertain the nature of their termination. They end on the surface 

 a few feet from the escarpment and clearly show that they formerly 

 continued on the same gradient (fig. 95), for an undeterminable 

 distance. The feature is significant because it augments and em- 

 phasizes previous indications that the valley once was bordered by 

 a ridge long since eroded away. Some of the material was swept 

 down across the site, forming the layers above the archeological 

 horizon, but the bulk of it has been carried away in the opposite 

 direction, thus producing the terracelike character of the formation. 



The thick, dark-colored stratum apparent in the photographs just 

 above the floor of the excavation is a soil zone produced by lush vege- 

 tation during a period of heavy precipitation when growing condi- 

 tions were more favorable than those of recent times. The layer is 

 important because it was the means of correlating the site with geo- 

 logic phenomena attributable to the waning of the Glacial period. 

 The artifacts and bones occur along the upper surface and in the 

 lighter-colored stratum below, some projecting into the zone above 

 (fig. 96). The light layer consists of a mixture of wind-blown sand 

 and decomposed material from the top of the tufaceous clay deposit 

 underlying the whole area. The stratum is evidence for a dry and 

 windy era associated with a minor oscillation in the last ice sheet 

 and establishes a slightly earlier occupation than previously supposed. 

 The positions of the artifacts and bones show inhabitation before the 

 onset of the wet cycle and that tenancy persisted for a time after its 

 inception but did not continue throughout its duration. The climate 

 may have become too damp, possibly somewhat cooler as well, and 

 as a consequence the animals and people moved on, probably farther 

 south along the edge of the Plains, where traces of their former 

 presence appear in several places. 



The excavated area yielded more specimens than any of comparable 

 size yet dug. The artifacts comprise typically fluted Folsom points, 

 fluted knives, knives made from channel flakes removed from the 

 faces of the points, other kinds of flake knives, a large variety of 

 scrapers including several forms of the spokeshave type, flakes with 



