Academic journal article Southeastern Archaeology

Geophysical Survey of Complex Deposits at Ramey Field, Cahokia

Academic journal article Southeastern Archaeology

Geophysical Survey of Complex Deposits at Ramey Field, Cahokia

Article excerpt

Research Goals

Archaeologists in the Southeast United States have found that near-surface, high-resolution geophysical surveys (Heimmer and De Vore 1995) can benefit investigations of large late prehistoric sites in two important ways. Large-area magnetic field grathent surveys, for example, can provide a more nuanced understanding of a site's overall settlement plan (Hargrave 2005; Kvamme 2003), particularly the distribution of subsurface defensive, residential, and public or ritual facilities relative to plazas and mounds that are visible on the surface. Geophysical surveys can also allow small-scale excavations to be targeted on selected features, greatly improving the ratio of information return to cost and site damage (Butler et al., this volume; Hargrave 2006; Kvamme et al. 2006).

One characteristic of large, complex sites that can limit the usefulness of geophysics is the presence of rich midden. Each data value recorded by many geophysical techniques (ground-penetrating radar is an exception) is influenced by all deposits within the sensor's effective range. Where features are closely spaced, occur at various depths, below or within a stratum of rich midden, it may be impossible to resolve individual features such as pits, house walls, or floors. Given this, is the use of near-surface geophysical techniques at such sites or site areas a wise use of one's limited resources? This paper explores the benefits and limitations of magnetic field grathent and electrical resistance surveys at Ramey Field, a portion of the Cahokia site that was known to have deep, rich deposits as well as a potential for large-scale architectural remains.

Ramey Field

Located immediately east of Monks Mound, Ramey Field is bounded on the north by Cahokia Creek, and on the south by Collinsville Road (Route 40) (Pauketat and Koldehoff 2002) (Figure 1). The stockade marks the approximate eastern limit for this study, although Ramey Field extends well beyond it. The survey area occupies one of the higher elevation portions of the site. It is situated on a natural levee of the Edelhardt meander scar (Kelly 1982:6). Early historic observations indicate that Cahokia Creek was much wider and deeper than one might suppose based on its current heavily silted channel (Brackenridge 1868:254; Dalan et al. 2003:90; Tucker 1942:46).

The survey area is located within Cahokia's Central Precinct, an area that was architecturally and symbolically delimited in several ways. Monks Mound and the paired Round Top and Fox mounds (numbered 38, 59, and 60, respectively) occupy opposite ends of the Grand Plaza (Dalan et al. 2003; Fowler 1997). Geophysical and archaeological investigations by Dalan (1991, 1993) and her co-workers (Holley et al. 1993) demonstrated that the naturally undulating site of the Grand Plaza was first used as a source of soil for mound construction then reconstructed as a level, massive anthropogenic feature. That landscape transformation began at the end of the Late Woodland period (ca. A.D. 900), with the Grand Plaza and Monks Mound in place by the end of the Lohmann (A.D. 1050-1100) phase (Pauketat 2004:11). The first of four stockades was constructed during the Stirling (A.D. 1100-1200) phase, surrounding at least 18 mounds and an area of from 60 to 160 hectares (most of the western and northern stockade alignments have not been located) (Iseminger et al. 1990:31; Milner 1998:112).

Other major plazas, defined by the mounds that surround them and surface artifact density, were located outside the stockade on the east, north, and west in a cross-like configuration, with Monks Mound at the center (Kelly 1997:143, 145). This quadripartite arrangement of plazas may not be cause to expect symmetry in the distribution of other feature types. Kelly (1997) notes, for example, that the western plaza is defined by a small number of mounds that vary greatly in size, whereas the east plaza is defined by numerous mounds of far less disparate proportions. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.