Environmental Work

Geomorphological Survey and Sediment Coring

2006

As part of the broad goals of the Central Lydia Archaeological Survey, we aim to determine the geomorphological, topographical, and paleoenvironmental history of the area. In 2006 these aims were addressed with a program of lake sediment coring and bathymetric (underwater topography) survey in the Gygaean Lake (Marmara Gölü). Prior to work on the lake, necessary permissions were obtained from the Koruma ve Kontrol Genel Müdürlüğü of the T.C. Tarım ve Köyişleri Bakanlığı, with especially important assistance from Kadir Özdemir and Erkan Mutlu, two Su Ürünleri Yüksek Engineers from the Manisa İl Tarım Müdürlüğü; the latter two even provided a tour around the lake on their official vessel, the “Gediz I.”

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The coring program was overseen by Dr. Mark R. Besonen of the University of Massachusetts, Amherst, and was conducted during five days on the lake. Prior to coring, a roughly 2.5 x 2.5 m coring platform was constructed from wood and plastic barrels. This was towed to coring locations behind the “Balıkçı,” a local fishing vessel rented from Mehmet Ali Kerse, the local shopkeeper from the village of Tekelioğlu. Over the course of lake work, 14 lake sediment cores were extracted with a five-centimeter diameter, modified Livingstone Square-Rod Piston Corer from ten different locations in the western area of the lake, north-northwest of Tekelioğlu. Observable lake sediment stratigraphy was noted when the cores were removed, and at present it is possible to say only that each of the cores ended at a uniformly hard and partially oxidized clayey layer that may represent a once dessicated lake floor or a flood plain. Alternating organic, carbonate, and sterile lake muds stratified above the uniformly hard layer may suggest alternating periods of deep water and dessication, but full interpretation will have to await analyses to be conducted in the United States by Dr. Besonen.

In addition to the coring program, a hydrographic or bathymetric survey of the lake was begun in 2006. The depth and underwater topography of the Gygaean Lake is currently not well documented. The establishment of lake bathymetry will help guide our coring program, and will provide data for reconstructions of paleotopography. Using a Garmin GPS178 Sounder, a combination Global Position Satellite (GPS) receiver–depth sounder, we were able to conduct a hydrographic survey of parts of the western area of the lake from the “Balıkçı.” Due to the abundance and density of lake grasses, however, the survey was successful only in the western half of the lake, and in areas where lake grasses were absent. At present we can say that the deepest area of the lake during the late spring / early summer period of high water is north and northwest of Tekelioğlu, where depths of up to c. 6.1 meters were recorded with the GPS-depth sounder. In order to complete the bathymetric survey in an accurate fashion, we will have to return another time when the grasses are less pervasive, probably before 15 April or after 30 August, according to local information.

2008

One of the primary goals of CLAS is to understand long-term cultural changes with respect to concurrent changes in the central Lydian environment. In 2006 we began to address this goal with a program of lake-sediment coring under the supervision of Dr. Mark Besonen in which we extracted several cores from the bottom of the Gygaean Lake to help determine its history of formation and fluctuation over time and to recover proxies for ancient environmental conditions. A preliminary result of that work seemed to confirm an earlier proposal that the Gygaean Lake initially formed somewhere to the east of its current basin and gradually migrated into its current position (Hakyemez, Erkal, and Göktaş 1999; Besonen and Roosevelt 2008). In 2008 we aimed to further investigate this theory to help refine our preliminary understandings. All work was carried out under the supervision of Dr. Besonen, and preliminary and final reports were submitted to the Regional Directorate of Maden, Tetkik ve Arama (MTA) in Bornova, İzmir.

img_7499Over the course of four days and using a gouge auger with 6 cm and 3 cm diameter barrels, we obtained ten sediment cores of shallow subsurface stratigraphy to the east and southeast of the modern lake basin, with core lengths ranging between 4–8 meters. Core sediment stratigraphy was logged at the field house and three types of subsamples were prepared for export to the US for expert analyses: A) samples for magnetic susceptibility analysis (in clear plastic cubes; 228 total); B) samples for general analysis (in clear plastic bags; 49 total); and C) samples for radiocarbon analysis (in aluminum foil in clear plastic bags; 4 total). Export permits were obtained from the Manisa Museum.

Based on observations made during core logging, we encountered lacustrine sediments beneath modern floodplain sediments in multiple core locations, presumably revealing ancient configurations of the Gygaean Lake. In addition, the presence of scoria pebbles in one sediment core (MGT-16JUN2008-AUG-1) appears to indicate that a former course of the Hermos (modern Gediz) River passed at least as far north as the location of this core. These preliminary observations further support the theory of the migration of the Gygaean Lake (Hakyemez, Erkal, and Göktaş 1999), and that its formation results, at least in part, from the alluviation of the Hermos River.