Edgewater Park (13JH1132): A Late Archaic Site

by William Whittaker, 2007

The Edgewater Park Site (13JH1132)

Coralville, Johnson County, Iowa

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In Coralville, just north of the Marriott Hotel along the Iowa River, the OSA excavated a Late Archaic site, occupied ca. 3,800 years ago. This small site had organic preservation, and included a central hearth and activity areas, including deer processing, lithic reduction, and discard areas. The excavated soils, associated with a buried A horizon, were wet-screened. 
The people at the Edgewater Park site 3,800 years ago were mobile hunters and gatherers. Their site was a temporary camp along the Iowa River where the inhabitants chipped stone tools including hunting weapons, sat around at least two hearths, and fished and hunted. The types of stone used for tools suggested they had just come down river from central or northern Iowa, and plants found at the site indicated camping in late summer or early fall. It is reasonable to assume that they were probably headed south, and the site offered a good spot to rest and resupply before continuing their trip toward the Mississippi River valley for winter.
The site was found about 4 ft below surface. Excavation proved very slow, since the site rested below the water table and had to be continuously pumped. Archaeologists used this water to wash excavated soil through fine mesh, which resulted in the collection of very small artifacts. Although little could be seen in the muddy clay during excavation, the residue of burned earth and charcoal, small stone flakes, and butchered animal bone made it possible to determine the location of hearths, flintknapping (stone-tool making) areas, and butchering spots. Soil samples from the site contained seeds of little barley, a plant that is not native to the area and barnyard grass, a local plant similar to millet. 
These seeds suggested the people at Edgewater were involved in the earliest stages of domestication, the movement of plants to new areas. The Edgewater site is younger than eastern U.S. sites where there is confirmed evidence of domestication, but older than sites in Iowa with evidence of domestic plants. More than 4,000 years ago domesticated plants appear in the southeast U.S., with the oldest confirmed horticulture in Iowa ca. 3,000 years ago at the Gast Spring and Sand Run sites.
Other people were beginning to grow domesticated plants in the southern Mississippi River region at this time, and it is likely that the people at the Edgewater Park Site were directly or indirectly in contact with them. While the occupants did not grow crops, they were changing the way they produced food, shifting towards plants that would later be domesticated, a necessary step towards becoming farmers. This continued transition to agriculture can be seen at other sites in Iowa.  The 2800-year-old Gast Spring Site in Louisa County has the earliest unambiguous evidence of domesticated plants in the state, including squash, goosefoot, and little barley.

To Visit:

The Edgewater Park site was located north of the parking ramp of the Marriott Hotel and Conference Center, 300 E. 9th St.  On the second floor of the Marriott, there is a public display about the site that includes the excavated spear points.

Want to Learn More?

Whittaker, William E., Michael T. Dunne, Joe A. Artz, Sarah E. Horgen, and Mark L. Anderson
2007 Edgewater Park: A Late Archaic Campsite along the Iowa River. Midcontinental Journal of Archaeology 32:5–45.
Edgewater Park excavation map

Edgewater Park excavation map
Points recovered from Edgewater Park

Points recovered from Edgewater Park
Digging muddy clay soils

Digging muddy clay soils at Edgewater Park. Excavation was a muddy mess, every morning the excavation would fill with water that had to be pumped out.
Excavation at Edgewater Park

Excavation at Edgewater Park
Wet screening at Edgewater Park

Wet screening at Edgewater Park. The soil was too clay rich to screen dry, but this clay also helps preserve flora and fauna.
Soil analysis at Edgewater Park

Soil analysis at Edgewater Park. Constant pumping kept the water levels down for excavation.
Schematic map of activity areas

Schematic map of activity areas, based on artifact distribution