Underwater archaeological remote sensing survey has been a consistent regulatory requirement for decades. For many years, these surveys emphasized the identification of shipwrecks using side-scan sonar and magnetometers. However, during the last decade the sub-bottom data from these surveys has normalized submerged paleolandscape research, which is no longer a niche activity dominated by researchers and datasets from the Gulf of Mexico. Consistent sub-bottom paleolandform reporting from underwater geophysical survey has created a challenge for regulators and surveyors when existing guidelines do not address sub-bottom datasets, paleolandscapes, and submerged precontact archaeology. This paper discusses how submerged landforms and precontact archaeology may be addressed when regulatory guidance is minimal. I review strategies from successful survey projects and ongoing work. The goal for this paper is to further the discussion of regulatory best-practices for sub-bottom paleolandscape survey, submerged geoarchaeology, and effective paleolandform and underwater archaeology management.

Magnetometer data from a recent archaeological survey near Sabine Pass, Texas detected miles of relict stream channels buried on the Outer Continental Shelf. The channels were “hidden” near zero, in the low-amplitude signals between -5 and + 5 nanoTesla. Magnetometer data in this amplitude range is routinely ignored when searching for submerged cultural resources, pipelines and geo-hazards, thus it remains unmapped and unconsidered following most marine geophysical surveys. Correlation of magnetic anomalies with paleo-channels, incised into the top of the Pleistocene-age Beaumont Clay, was confirmed by sub-bottom profiles. Paleo-channel courses were mapped in detail beneath biogenic gas fronts, perhaps for the first time, using only low-amplitude magnetic data. This technique has potential to supplement both past and future studies of marine paleo-geography. Reexamination of legacy data might detect previously missed paleo-channels in areas of poor seismic penetration, while also helping to determine the geographic and depth-of-burial limits of this method.

Personnel from Coastal Environments, Inc., Louisiana State University, and members of the Chitimacha Tribe of Louisiana, conducted archaeological investigations at sites 16SMY17 and 16SMY95 to identify potentially intact midden to be protected by construction of a living-shoreline barrier along the eastern edge of East Cote Blanche Bay. Using grant funding provided by the National Oceanic and Atmospheric Administration to the Chitimacha Tribe, the research included terrestrial and submerged probing, terrestrial augering, and near-inshore remote-sensing surveys. Side-scan sonar and magnetometer surveys utilized an autonomous survey vessel (ASV), while sub-bottom profiler survey employed a typical sensor and a standard survey boat. GPR survey was conducted by placing the antenna within a small dinghy that was propelled by a trolling motor, allowing survey in extremely shallow water. Using these techniques, areas of subsided and potentially intact midden were recognized offshore, along with disturbances from past oil and gas activities.

The investigation of inshore waterway systems for submerged landforms has the potential to further our understanding of late Pleistocene and early Holocene populations. This study evaluates such potential by characterizing inundated landforms within a section of Pensacola Bay likely to contain relict channels. Initial geophysical survey with subbottom profiler and side-scan sonar yielded spatial and stratigraphic information regarding submerged landforms that assisted in understanding the precontact landscape. Mapping of surfaces that have been buried since the last glacial maximum also provided locations for future geoarchaeological testing. The analysis and interpretation of data generated by this project will assist in the identification of geomorphological features with greater probability of containing intact archaeological deposits. This work contributes to the field of submerged precontact archaeology by identifying inundated terminal Pleistocene surfaces in the Pensacola Bay system, and further, yields data that might one day allow for the identification of sites.

The now-submerged cave systems in Quintana Roo contain abundant evidence of Pleistocene/Holocene human and faunal activity and interaction. From skeletal remains to evidence of mining and water collection activities, these caves continue to reveal a nuanced picture of life not often preserved at other paleo sites. Beyond the documentation of individual caves and artifacts, it is important to understand how both humans and fauna accessed, navigated, and exploited these caves as part of the larger landscape. Detailed analysis of cave entrances and cave morphology is necessary in understanding how these caves were traversed. In this paper, we present new and existing 3D datasets combined with observations from divers of the cave entrances from the systems of Sac Actun, Tux Kupaxa, and Sagitario. This represents a component of the overall project, which aims to demonstrate how access and use of these systems changed over the course of their postglacial inundation.