ARCHAEOLOGICAL OCEANOGRAPHY OF INUNDATED COASTAL PREHISTORIC SITES

摘要

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