This paper provides the first radiocarbon date from CA‑LAN-1, also known as the Tank Site. This important prehistoric site, long considered the “type site” for the Milling Stone Horizon (MSH), had never previously been radiocarbon dated. Some six decades after the site was first investigated, we provide the date and its specific context, its conventional and calibrated ages, and discuss the significance of this singular date to southern California prehistory.

This paper presents two more radiocarbon dates derived from CA-LAN-1 (also known as the Tank Site), located within the Topanga Cultural Preserve in Topanga State Park. Building upon the first date (published in this journal in 2015), the new dates derived from the collections held at the Phoebe Hearst Museum confirm the age of the early component at the site yet suggest the existence of probable bioturbation that has potentially obscured the age of the presumably younger ìTopanga IIIî component. Specific information on the contexts of these dates, their conventional and calibrated ages, and a discussion of their significance relative to the rest of the site deposit and to the region as a whole is presented below.