Nov 2005:
C14 dating of carbonate coating (Sample 3) from the interior of the quarry gave a calibrated date of 2470 BP+/- 40 yrs.
This carbonate is thought to be the result of microbacterial action.
Since this sample was composed of the total accumulation of the carbonate over the life of that part of the quarry, the C14 date is only the average of the ages of the material in the sample. For instance, if the carbonate has grown uniformaly over the whole life history to the present, first activity might date as old as 4940 BP. It is expected that the growth was likely more rapid earlier when the climate was moister than present.
Future Activity:
Obtain C14 dates on thinner layers of the carbonate composing the carbonate coating of the quarry.
July 2005
Optical Stimulated Luminescence (OSL) will be run on samples of the silica crystals (sand) from 5 layers of the sampled fill. The processing of these samples is in progress. Results are expected before the end of the year.
