Date of Award
Doctor of Philosophy in Oceanography
The field of shallow underwater archaeology has grown significantly during the last century, especially since the development of advanced technologies such as the self-contained underwater breathing apparatus (SCUBA). Other advanced technologies, such as high-resolution geophysical surveying systems and robotic undersea vehicles, which have been used extensively in the oceanographic sciences during the last several decades, are now being used in the archaeological sciences to investigate underwater sites representing human history. These technologies, in addition to the oceanographic and geophysical methodologies for exploration, prospecting, and site surveying, now form the technological basis of the nascent discipline of "Archaeological Oceanography ." This discipline combines the traditional methodologies of archaeology with those of oceanography to search for, investigate, document, sample, and analyze submerged cultural remains. For the most part, these remains are shipwrecks, but other submerged sites, such as drowned prehistoric terrestrial sites, have been discovered and recognized as significant to our understanding of human history. The major process by which these sites become submerged is the inundation of low-elevation land masses due to the rising level of large bodies of water, both marine seas and inland freshwater lakes.
It is well-established that prehistoric human populations existed in coastal environments. Since the last Ice Age, about 20,000 years before present, global sea level has risen more than 100 meters in response to melting continental ice sheets. Nearly all present-day coastal embayments, lagoons, coves, inlets, fjords, channels, sounds, and shallow outer continental shelves throughout the world were exposed above sea level for several millennia as the glaciers retreated. In addition, the shorelines of most large inland lakes were at a much lower level during the dry times associated with the last Ice Age. The exposed low-elevation coasts, in addition to interior lake shorelines and adjacent landscapes, were gradually or, in some cases, catastrophically flooded by rising water levels. Any sites of human occupation along these coasts are now under water and draped by modern sediments. Many shallow water prehistoric archaeological sites have been discovered throughout the world, but systematic approaches to the survey of these sites have been infrequent and poorly defined.
Some researchers hypothesize that prehistoric humans migrated along coastal routes, but this has yet to be definitively proven. Most of these coastal routes followed shorelines that are now submerged on the continental shelves. In addition, inland bodies of fresh water would have been attractive to prehistoric humans during the last Ice Age as a valuable resource during a very dry climatic period in recent earth history. The paleo-environmental and archaeological features of these coastal settings are now preserved in the shallow offshore geologic record. Oceanographic and geophysical methodologies are directly applicable to the investigation of these features and used to study the "underwater environmental archaeology" of potential sites. Several diverse submerged coastal regions have been intensely surveyed for their prehistoric archaeological potential, and these represent the case studies presented in this investigation.
Offshore southern New England , in the vicinity of what is now Block Island, was once a habitable coastal environment that has now been naturally inundated by about 100 meters of rising ocean water. This environment, which was located along the fringe of the glacial ice ] during its maximum extent, has also been slowly uplifted by glacial rebound and reworked by modern coastal oceanographic processes. A number of archaeological sites have been found on Block Island, and exploration off its southern and western coasts has revealed an interesting landscape that would have been favorable to early human populations. Several ancient river channels and coastal lagoon features were investigated using geophysical mapping methods and sediment coring. Although further visual investigation is required, the submerged environmental archaeology of a paleo-Block Island reveals significant potential for the discovery of ancient human occupation sites.
During a dry time period critical to the advance of people in the New World, ancient Lake Huron was at a substantially lower elevation. From about 10,000 to 8,000 years before present, the shores of the lake were as much as 120 meters lower in elevation. Gradual refilling of the Lake Huron basin has occurred since that time, thereby inundating and preserving any potential sites of human occupation near the shoreline. A number of prehistoric archaeological sites and Pleistocene mammal remains have been discovered near the basin. Detailed mapping and exploration in Thunder Bay National Marine Sanctuary, off northeastern Lower Michigan, has revealed a number of submerged sinkholes, part of an evaporite and limestone karst geologic formation that can be traced onshore. Several sinkholes were investigated using geophysical mapping techniques and visually explored using a remotely operated vehicle. One sinkhole that was discovered in 90 meters water depth contains a unique deposit that could yield human cultural material, and this site will be the focus of future intensive geologic and archaeological sampling.
The Black Sea was once an isolated, inland, freshwater lake. Several advanced Neolithic cultures are known to have populated the surrounding coastal regions of the Black Sea. For this and other reasons, the region is an ideal location to explore for inundated archaeological sites. This body of water is suspected of being catastrophically inundated by rising marine water about 7,500 years ago. The inundation would have driven away the coastal population, but the sites that represent their habitat could be preserved in what is now a shallow marine setting, up to about 150 meters water depth. In addition, and due in part to the inundation, the deep waters of the Black Sea are devoid of oxygen, which means submerged archaeological sites near and below the anoxic interface are very highly preserved, as no organisms can exist to destroy them. Exploration off the northern coast of Turkey in the southern Black Sea and off the western Black Sea coasts of Bulgaria and Romania has resulted in several interesting discoveries that could represent significant archaeological sites. One location in particular contained what appeared to be a stone and wooden structure that sat atop a topographic high point at about 95 meters water depth in the submerged landscape. This has enormous potential to represent a significant pre-flood Neolithic archaeological site, and will be intensely examined and sampled using an advanced remotely operated vehicle system during a future expedition.
Although these case studies do not confirm or deny the existence of inundated prehistoric cultural sites in these locations, they do represent examples of diverse environmental settings that responded differently to the geologic and oceanographic processes following the last Ice Age. More work clearly needs to be done in this field, on the sites mentioned here and elsewhere, to learn more about the existence and preservation of submerged prehistoric archaeological sites. There is great potential for significant archaeological discoveries to be made using the available advanced oceanographic technologies to investigate submerged landscapes. Many mysteries surrounding the evolution, adaptation, and migration of the human species throughout the world could be solved by more detailed and advanced underwater exploration using the archaeological oceanographic approach described here.
Coleman, Dwight F., "ARCHAEOLOGICAL OCEANOGRAPHY OF INUNDATED COASTAL PREHISTORIC SITES" (2003). Open Access Dissertations. Paper 1133.