Archaeological Geology
In reviewing each year the efforts of archaeological geologists it becomes more and more apparent that most geologic methodologies are now being applied to archaeological problems. This review focuses on recent efforts to detail major Holocene landscape changes (especially in coastal regions) that have drastically altered a local human environment.
In coastal areas, relative sea-level change is often the dominant factor in geomorphologic evolution. Such changes are due to a mix of 3 geologic processes: eustatic sea-level rise or fall, vertical tectonic movements of the regional land mass, and addition to or removal of coastal sedimentary deposits. Sediment infill from eroding uplands has landlocked many ports of historic importance. Nearly 150 years ago C.T. Beke first presented geological evidence for a theory of delta advance at the mouth of the Tigris-Euphrates system. Cuneiform texts imply that the Sumerian city of Ur was a port, possible on a large fresh-water lake in the Euphrates delta; Ur is now more than 100 km from the sea.
The Nile River now has 2 main branches in it delta. Herodotus recorded 5 branches; Ptolemy listed 8. Vance Haynes, continuing his longrange work in Egypt, has reported on one ‘lost’ tributary. Studying geomorphic change in the western desert of Egypt, James Underwood and Robert Giegengack found an Acheulian hand ax made of Lybyan Desert glass. Although Acheulian hand axes are fairly common in the region, the discovery is the first of one made of that unique glass.
Farther west, along the North African coast of Tunisia, Reuben Bullard has been studying the Punic and Roman harbor areas of ancient Carthage, long buried by coastal sedimentation. North across the Mediterranean, in Greece, Rip Rapp, J.C. Kraft, S.E. Aschenbrenner and Christos Tziavos have reported on their paleogeomorphic studies on the long-standing question of the width of the pass at the site of the historic battle of Thermopylae, and the associated problems of historic and prehistoric access between northern and southern Greece. With John Gifford, they continued their study of Holocene coastal changes in the Peloponnese; last season’ work centered on the coast west of ancient Olympia.
Across the Aegean, in northwestern Turkey, J.C. Kraft, I. Kayan, and O. Erol illustrated the importance of geomorphic reconstructions of the ancient environs with their work near the site of Troy. Using subsurface data, they detailed the continuing landscape change since Troy was first settled, 5,000 years ago.
Frank Koucky has surveyed much of south-central Cyprus and described the geologic/geomorphic controls of settlement sites, travel routes, and natural resources from the Chalcolithic (earlier than 5,000 years ago) through the Medieval period. To the east, in northern Israel, William Farrand reconstructed a coastal landscaped rom 40,000 to 125,000 years ago in the vicinity of Carmel caves. The coastal plain has baried from 0 to 13 km in width. Using archaeological, geohydrological and paleoclimatological data, Curtis Larsen showed that Holocene land-use variations on the Bahrian islands in the Arabian Gulf depended primarily on water supply. The islands have suffered a steady depletion of artesian water since the end of the Pleistocene, and have become increasingly dependent on rain fall.
In England, the topic of archaeology and coastal change was the theme of 2 recent conferences integrating the work of geologists, archaeologists and biologists. Papers from those conferences appear in Archaeology and coastal change, published by the Society of Antiquaries of London. 9 chapters present extensive data on relative sea-level change and its effect on populated coastal areas.
In the New World, John Barber, John Adams, and Anthony Ranere presented evidence of the major influence of geological parameters on early adaptation of humans to the coastal environment on Panama. Middens formerly on the coast are now 8 km inland. Mark Brooks, Donal colquhoun & colleagues related archaeological sites to Holocene sea level in southeastern United States. They conclude that site types and locations support transgressive and regressive salt-water/fresh-water boundary movements in response to glacio-eustatism. James Howard and Chester Depratter, using a local pottery sequence as a dating tool, postulated a series of sea-level fluctuations and a tentative sea-level curve for the last 5,000 years for the Georgia coast. On the West Coast, Curtis McKinney used uranium-series ages of mammoth tooth enamel from Santa Rosa Island to deduce low-sea stands when the animals could reach the island across no more than a narrow strait. To the north, Dale Ritter and Norman Ten Brink studied the Late Wisconsin glaciofluvial terraces and the glacial chronology of north-central Alaska to determine that region’s potential for human occupation.
Historians, archaeologists and historical geographers have very few paleogeomorphic maps that delineate with any accuracy the shifting coastlines and meandering river systems of geomorphically dynamic areas during the last 10,000 years. The dramatically increased interest of geologists in archaeologically important regions could produce such maps if the research is published in map form.