H.R. Schmoll

Radiometric Dating of Marine Shells from the Bootlegger Cove Clay, Anchorage Area, Alaska

Four radiocarbon age determinations indicate that the Bootlegger Cove Clay was deposited about 14,000 yrs ago. A new uranium-series age of 15,200 ± 2,800 yrs supports the radio-carbon age. In this age determination, U 234 /U 238 activity ratios are measured and correction is made for extraneous Th 230 . Previous uranium-series age determinations, ranging from 25,000 to 48,000 yrs, did not employ these procedures, and are seemingly invalid. The Bootlegger Cove Clay, which has been designated the type deposit for the Woronzofian transgression, is here interpreted to represent a marine transgression following the maximum development of the glaciation of Wisconsin age rather than an interstadial event of mid-Wisconsin age or an older glacial or interglacial event.