Archaeological Geology
Although remote sensing in regional and site-specific surveys is not a new approach to archaeology, many advanced data-analysis techniques and software-filtering packages are being applied to satellite imagery, aerial photography, and electromagnetic/magnetometer data sets. That was the feeling at the 1986 symposium of the Archaeological Society of America. They symposium, Surveying & Prospecting for Archaeological Sites, was held in November in San Antonio.
It is now possible to extract useful information from historic-period sites that are complex structurally, as shown by Ralph R.B. von Frese, Ohio State University, Columbus, in his presentation. D.L. Rickman, National Space Technology Laboratory, used modified thermal-emission characteristics of soil, as seen in aerial images, to map buried cultural features in the Gulf Coastal Plain (Poverty Point site) and the Southwest (Chaco Canyon site).
Other presentations at the symposium: a mixture-modeling approach for recovering archaeological information from LANDSAT images of the Nile Delta, by Paul Buch and others, University of Washington, Seattle; remote sensing of transitory cultural features in the Costa Rica rain forest, by Payson Sheets, University of Colorado, Boulder; and prospecting with archaeological instruments of Lake Neuchatel, Switzerland, by Ervan Garrison, Texas A&M University.
Further evidence of current interest in remote-sensing techniques was seen in March 1986 Geophysics special issue on archaeology and geophysics. That issue was edited by Jeffrey C. Wynn, U.S. Geological Survey, Reston, Va., who also published a comprehensive review of geophysical methods used in archaeology (now known as archaeogeophysics) in the first volume of Geoarchaeology.
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| This section of late Pleistocene mastodont tusk was used for oxygen-istope analysis. Holes were drilled parallel to laminations in the tusk dentine and powder from each row was analyzed. An interval of more than 4 years old of the mastodont's life was studied using 4 to 5 samples a year. (Photo from Paul Koch and Dan Fisher, Univ. of Michigan, Ann Arbor) |
North American field work in archaeological geology is still active. In addition to regional projects mentioned in 1985, others are worth nothing because they stress archaeological geology as a research tool. 2 projects involve geoarchaeological surveys in Alaska; the Nenna River Valley of central interior Alaska (Roger Powers and students, University of Alaska, Fairbanks), and the Seward Peninsula area (Jean Schafe, national Park Service, Anchorage, with David Hopkins, University of Alaska, Fairbanks).
In southern Arizona, Michael R. Waters, Texas A&M University, continued his investigation of late Quaternary lacustrine stratigraphy and geochronology of ancient Lake Cochise (Wilcox Playa) in conjunction with an archaeological survey by the Amerind Foundation, Dragoon, Arz. Waters also interpreted the geomorphology and paleohydrology on several alluvial pedimonts (bajadas) and related those to prehistoric Hohokam flood-water farming systems.
North Texas State University, Denton, recently began a cultural-resource management project that is significant to archaeological geology. C. Reid Ferring, of that institution, reports that the project area covers 60,000 acres in 2 reservoir areas of the upper Trinity River basin, north-central Texas. Archaeology studies of prehistoric sites are supplemented by evidence of late Quaternary geomorphology, stratigraphy, and soils.
In addition to field work, geologic studies are being done using IBM’s ERDAS geographic information system. That permits simultaneous analysis of multiple data sets including geomorphic, stratigraphic, sedimentologic, topographic, and LANDSAT-based vegetation overlays on U.S. Geological Survey topographic base maps. The ERDAS system is used to develop a multivariate model of site construction, environments, preservation potential, and detectibility.
Ferring is also trying to identify 19th century site-distribution pattens in the basin and compare them to historic vegetation, soil-fertility, land-use, and erosion patterns. When combined with studies of post-occupational disturbance through bioturbation, pedotubation, and erosion, those historic records may be used to calibrate recent processes of site formation. Thus, the reconstruction of well-dated short-term site-forming processes of last century might help explain similar processes earlier in the Holocene.
Jonathan Davis and Steve Durand (Desert Research Institute, Reno) have been experimenting with direct video input of geoarchaeological data into microcomputers using inexpensive peripherals. Recently they have submitted a Technique Development Proposal to the National Science Foundation’s Archeometry Program. They propose studying several aspects of direct input of artifact, bone, and obsidian hydration-rim images using a video camera and without handling specimens. That promises to be more efficient and accurate than hand measurements.
Much field work continues to center on the eastern Mediterranean. The eruption of Thera (Santorini) at about 1,500 B.C., in the southern Aegean focuses on the problem of its precise timing and effect on the decline of the Bronze Age Minoan civilization of Crete. Charles and Dorothy Vitaliano, Indiana University, Bloomington, note that their bibliography of Santorini references contains 241 entries.
The recent discovery of Theran pumice ash in a late Minoan stratigraphic context on Pserira, off the coast of Crete, is the fifth such find, and reinforces the conclusion of G.R. Rapp Jr., University of Minnesota, Duluth, the Vitalianos, and others, that the eruption was not responsible for the final destruction on Crete.
Fragments of Theran Bronze Age volcanic ash were discovered in 1985 in cores samples taken from the Nile Delta by D.J. Stanley, Smithsonian Institution, Washington, D.C., and others. The study was part of a regional multi disciplinary program to interpret the late Quaternary to Recent history of the Delta.
The project is defining the sediment facies in more than 30 cores, some of which are 50 m long, by x-radiography; size analysis; scanning electron microscopy; mineralogy of clay, silt, and sand; and the interpretation of the biogenic components )foraminifera, ostracods, and pollen). More than 100 radiocarbon dates are now available.
The aim is to outline changes in the positions of the former coastlines and depositional environments such as pre-Recent Nile distributaries and their deltaic lobes, and to define the late Pleistocene to Holocene paleogeography of the area at times when early archaeological sites in the eastern Nile Delta were occupied. Phase II of that program includes further exploratory drilling in 1987.
Information for identifying earthquakes in the archaeologic record (archeoseismology) has increased considerably from the excavations at the Roman city of Kourion in southwest Cyprus. Many of the structures excavated recently by David Soren, University of Arizona, Tucson, may have been destroyed by a major earthquake known from historical records to have struck the eastern Mediterranean July 21, 365.
Well-preserved human skeletons have been found in rooms of a house currently under excavation. Reuben Bullard, University of Cincinnati and Cincinnati Christian Seminary, is studying the site’s geology. He reports that directional structure throws and sinusoidally warped floors attest to the character and forces of the quake pules.
New analytical techniques that give researchers information about prehistoric subsidence, climate, and diet continue to be refined. For example, in 1983, Thomas Loy, British Columbia Provincial Museum, Cancouver, reported on a technique for detecting and identifying animal blood residues on prehistoric stone tools. Loy and James Dixon, University of Alaska, Fairbanks, have now begun research on blood-residue analysis of Northern Paleo-Indian lithic artifacts that may show which animals were preferred by big-game hunters.
Daniel C. Fisher, University of Michigan, Ann Arbor, developed methods to find the season when late Pleistocene mastodons and mammoths died, by looking at patters of growth laminations in tusk and molar dentine. One purpose of that research is to document the seasonal incidence of mortality in butchered proboscidians, compared to those that died naturally.
Recently, that work took an interesting turn with the addition of oxygen-isotope analyses by Paul Koch, University of Michigan, Ann Arbor. Koch and Fisher demonstrated a cyclic (annual) pattern of variation in d15O values in which winters can be identified as zones of dentine that are isotopically light. The techniques, described at the November GSA meeting in An Antonio, may help answer questions about climatic seasonality, based on the amplitude of the annual isotopic fluctuations.
Finally, at the GSA meeting P. Edgar Hare, Marilyn L. Fogel, Thomas W. Stafford, and Thomas C. Hoering, all of the Geophysical Laboratory, Carnegie Institution of Washington, D.C., reported on the stability of nitrogen isotopic patterns in certain amino acids from fossil proteins. High-precision chromatographic separation of individual amino acid species makes it possible to analyze bone collagen from herbivores and carnivores and estimate the number of trophic levels through which the amino acids have been cycled.
The implications for studies of late Pleistocene high-latitude ecosystems are significant. And the same isolation technique may be used to radiocarbon date (with an accelerator mass spectrometer) individual, relatively stable amino acids such as hydroxyproline from bone samples that were previously thought to be unsuitable.
For the first time, a GSA Penrose Conference was devoted to archaeological geology, with discussions on site reconstruction and sedimentation, lithic and metal artifacts, chronology, provenance studies, and remote sensing. It promises to affect the direction of future research in the field.
