Date of Award
Doctor of Philosophy in Oceanography
Robert D. Ballard
Our ability to understand and interpret archaeological data collected from the excavation of an archaeological site is constrained by our capacity to investigate it. This is often limited by our understanding of the surrounding environment and the modern landscape. This dissertation is composed of three separate studies, each of which examines the environmental and oceanographic contexts of archaeological sites using geophysical and geochemical analyses. The focus of these case studies is to initiate the process of determining the oceanographic and geological histories of the modern sites. Viewing sites from their abandonment to the present day provides an understanding of the ways these sites have changed and come into equilibrium with the surrounding environment over time. By establishing such environmental parameters for each of these regions, this research provides a framework from which future overall site interpretations can be based. Two of these studies focus on the documentation and characterization of shipwreck sites, while the Belize chapter examines the geochemical composition of marine limestone formations at a Maya site.
This dissertation addresses the following research:
1. The issue of damage to shipwreck sites caused by the operation of mobile fishing gear has only recently begun to be addressed by the archaeological community. However, the nature, extent, and intensity of this damage has yet to be quantified. Acoustic and video surveys conducted between 2008 and 2010 located and imaged sixteen ancient shipwrecks around the Bodrum and Datça Peninsulas, Turkey, many of which were heavily damaged by trawling activity. The results of this research illustrate the unfortunate reality that many wreck sites in the Aegean Sea are heavily damaged by modern fishing activities. Quantifying the extent and intensity of trawl scars on the seabed further reveals the geographic spread of damage in these areas. The results of these mapping projects call attention to the dismantling of cultural sites by the use of mobile fishing gear on the seabed. By comparing the number of broken artifacts on these wreck sites to other sites that have escaped the effects of trawling, such as those in the Black Sea, we demonstrate that shipwrecks that are or were at one time in areas of trawling activity show a considerable amount of damage. The location and condition of these wreck sites helps map and quantify past and recent trawling activity, and pinpoint areas on the shallow coastal shelf where additional trawling restrictions or protected zones may be able to help the preservation of archaeological material.
2. A continuation of exploration of the coastal area of the southern Black Sea off Sinop and Ereğli, Turkey in 2011 documented additional areas at the transition zone along the oxic/anoxic interface. Push cores collected with an ROV from sediments underlying the oxic, suboxic, and anoxic waters were analyzed for geochemistry, meiofauna, and microbiology to help characterize this transition zone. During the course of side-scan sonar surveys, nine shipwrecks were located at various states of preservation, all within 100-115 m depth and ranging from the 4th century BC to the early 20th century. Many of these wrecks have wooden components well preserved due to the influences of the anoxic waters being washed up along the shelf by internal waves. However, many of these sites have also been heavily damaged by bottom trawling along the seabed up to the shelf break, highlighting the drastic threat such activities present to archaeological sites.
3. The carbonate bedrock of northwestern Belize is poorly understood both geochemically and from the standpoint of the use of stone as the building blocks of ancient Maya sites and monuments. This research analyzed 67 limestone samples collected from sites in the Three Rivers Region of Belize with ICP-MS and ICP-AES to characterize the major, minor, and trace element chemistry of the bedrock of the region. Bedrock, quarry, and possible monuments were sampled for this study for the purposes of tracing the movement of monument stone to either the local bedrock or quarries, or to determine if it was imported from outside of the sites’ core. At Chawak But’o’ob along the flank of the Rio Bravo, changes downslope in Mg concentration suggest a leaching of the bedrock by meteoric waters based on differences in porosity. However, at Maax Na, a hilltop site, such leaching is not as apparent. Many monuments were found to be composed of stone with the same trace element chemistry as the bedrock, although this does not preclude them from being monuments. A few monuments were shown to be composed of material with a different chemical composition than the local bedrock, which included some of the stelae at Maax Na, and appear to have been made of stone imported from outside the site.
Brennan, Michael Lee, "Cultural Sites as Platforms for Environmental Characterization of Marine Landscapes" (2012). Open Access Dissertations. Paper 75.