GEOMORPHIC CONTROLS ON THE DISTRIBUTION OF ARCHEOLOGICAL SITES IN EGIIN GOL, NORTHERN MONGOLIA

Geomorphic processes influence the apparent distribution of archaeological sites in two ways: a) by controlling the distribution of resources, either food or shelter and b) by influencing the preservation of sites. An understanding of the timing and rate of the development of land forms provides a basis for stratifying a landscape and allows identification of areas of higher probability for containing archaeological sites. This becomes particularly important when archaeological surveys have to be undertaken in a limited time frame.

The Egiin Gol river is a tributary of the Selenge River in northern Mongolia. A proposal to build a hydroelectric dam on this river in 1990 resulted in an intensive survey to identify all archaeological sites in the valley which would potentially be impacted by this project. The survey showed evidence for habitation in the Egiin Gol from circa 30,000 yrs BP to the present. Concurrent with the archaeological survey, a detailed map was made of the land forms in part of the survey area. Relative ages of the surfaces of land forms were assessed on the basis of soil development and the occurrence of specific artifacts in subsurface strata.

A large part of the survey area is occupied by the Egiin Gol river valley and major tributaries. The active floodplain and the lowest terrace of these fluvial systems contained predominantly recent (20th century) sites, whereas older sites were preferentially found on the higher and older terraces both in the main valley and along the tributaries. Loess deposition occurred on this landscape probably in the late Pleistocene. The loess is preferentially preserved on older depositional land forms, particularly on former terraces of the Egiin Gol and its tributaries. Therefore, these areas have a high potential for containing sites that have been buried by loess deposition or post-depositional reworking.

Based upon the results of the Egiin Gol geo-archaeological survey, it is clear that stratifying a survey area on the basis of land form age and type and incorporating this information in the methodological design of an archaeological survey may increase the effectiveness of studies of past land use.