Submerged prehistoric sites investigated in northwest Florida along the margins of the drowned Aucilla River channel (or PaleoAucilla) extend our understanding of prehistoric settlement patterns and paleolandscape utilization. Bifacial and unifacial tools indicate Late Paleoindian and Early Archaic logistical activities at these sites, as well as later Middle Archaic occupations. Other evidence for terrestrial conditions at these sites include extinct and extant terrestrial faunal remains, in-place tree stumps, and possible eroded middle Holocene shell middens. This report outlines the methodologies used for site investigations, and then discusses the geomorphic setting, character, cultural-historical connections, and timing of full inundation for these offshore sites. During late Pleistocene and early Holocene times, the coastline was much farther out on the continental shelf, and this segment of the PaleoAucilla was forested and well inland. Later, during the middle Holocene stages of transgression, the segment was more of a wide grassy marsh with brackish water tidal creeks and oysters. In this continental shelf setting, submerged archaeological sites remain in clustered arrays accessible by underwater archaeological methods, and the data provide a critical supplement to our present understanding of late Pleistocene and early Holocene settlement patterns and paleolandscape utilization.

The distribution of projectile points over broad geographic areas yields important insights about Palaeoindian settlement pattern and history. While traditionally viewed as a Great Plains adaptation, the data show that fluted points are far more common in Eastern North America. These artefacts are not evenly spread across the landscape, furthermore, but occur in distinct concentrations. Within some of these areas distinct cultural traditions quickly emerged, something that appears tied to the sudden onset of the Younger Dryas.

A compilation of 63 stratigraphic situations with evidence for human presence and two or more radiocarbon ages older than 10,500 B.P. has been processed to increase the accuracy and precision of the estimated ages and to compare their distributions at hemispheric scale. The compilation was developed to perceive patterns of population expansion and to plot early sites in their temporal and geographic order. The use of radiocarbon dates as data, criteria for inclusion in the compilation, the statistical processing methods used, and effects of controlling for precision and accuracy are described. The results indicate three earliest mean ages with great distance from each other in North and South America by 12,000 B.P., slightly later mean ages in Alaska, and the abrupt occurrence of Fluted and Fishtail Point sites at the beginning of the Younger Dryas climatic reversal (YD). One interpretation of these data is that there were different colonizing groups settling into different parts of the hemisphere in near-contemporaneity. Another is that Fluted and Fishtail Point sites may represent population relocations due to YD related ecological disturbances at the shorelines of those times. Corollary to the conclusions of early population diversity is the possibility of landfalls of people from areas other than Beringia in the late Pleistocene.

Underwater geoarchaeological research in Apalachee Bay, in the northeastern Gulf of Mexico off northwest Florida, has enabled the reconstruction of portions of the karstcontrolled paleodrainage system, the discovery of several inundated prehistoric archaeological sites, and the exposure of sediments accumulated during the drowning of the continental shelf. Diagnostic artifacts discovered at the sites included chipped stone tools and debitage indicating Paleoindian, Early Archaic, and Middle Archaic occupation. A geoarchaeological model using terrestrial analogs was used to locate and investigate inundated sites. Methods employed include seismic profiling, vibracoring, diver tow surveys, diver collection transects, and induction dredge excavations. We document evidence for sea-level rise, related environmental succession and site formation processes for indundated prehistoric sites in the Apalachee Bay region from approximately 8000 to 6000 yr B.P.