As noted earlier, in some areas of the site the Zone II deposits are over one meter thick. In some of those areas, particularly up against the detached slab which forms the south side of the gully, vertebrate accumulations are relatively dense, and bone preservation appears quite good. The combination of relatively abundant fauna and deep stratigraphy allows one to look at faunal changes in more detail than is revealed in the faunas organised by zones. Three excavation units are considered in more detail here. These are unit 3, excavated in 1983, and units 26 and 28, excavated in 1990 and 1991. The Zone II deposits in unit 3 were excavated in a series of arbitrary 10cm levels in 1983. Radiocarbon dates and the depth of the unit suggest that unit 3 did not contain the lowest part of the zone II deposits. Units 26 and 28 were both excavated into the Zone I deposits, and both contain a complete Zone II sequence. These two units were excavated stratigraphically, and subtler changes in sediments defined the different layers recorded. Some of the the thicker layers were also excavated in arbitrary levels
MICROSTRATIGRAPHIC FAUNAL TRENDS more -->
In order to demonstrate the change from open to forested conditions in these units, the relative frequency of ground squirrel and snowshow hare are plotted. The bars on the left are from units 26 and 28, and the bars on the right are from unit 3. The bars represent layers or levels, and are arranged in sequence for each excavation area. The lowest bars are from lower Zone IIb, while the upper bars are from Zone IIIa. The radiocarbon dates are all from the excavation units, except the uppermost date which is from a unit adjacent to 26 and 28.
From about 10,500 to 10,000 B.P. the small mammal assemblage was dominated by ground squirrel, and this conforms to the overall pattern for one IIa and IIb. Starting at about 10,000 B.P. there is an increase in the frequency of snowshoe hare relative to ground squirrel, and by about 9700 B.P. ground squirrel has almost completely disappeared and snowshoe hare is dominant. Tree ring calibration is not available for the full range of zone II dates, but it aappears that the transition from open to forested conditions is unlikely to have taken more than 500 calendar years. If one simply calibrates the two dates which best mark the beginning and end of the transition, a figure of about 250 years seems plausible.
