Conference Name: Geological Society of America Annual Meeting & Exposition 2010: Reaching New Peaks in the Geosciences
To predict undiscovered archaeological sites in the Lower Grand River, we mapped known archaeological sites using color and infrared aerial photos, digital raster graphics, and digital elevation models. We interpreted the geomorphic and environmental settings of sites using this preliminary geographic information system. We found both spatial and temporal patterns in site location.
The Lower Grand River valley is cut into Quaternary glacial sediments that formed during the retreat of the Laurentide ice sheet ~16,000 to 13,000 14C years before present (B.P.). Initially the glacial Grand River was graded to Glacial Lake Chicago. Next, the Grand River incised due to the Chippewa low stand ~9,000 14C B.P. The first inhabitants were the Paleo-Indian culture which occupied the valley ~11,000 14C B.P. By 10,000 14C B.P. the climate of the region supported deciduous forests. This corresponds with the start of the Archaic period, which ended ~2,500 14C B.P. Between ~6,000 and 5,000 14C B.P. a transgression inundated much of the Lower Grand River Valley during the Nipissing high stand. By ~4,000 14C B.P. Lake Michigan had reached its current level resulting in down cutting of the Grand River. The evidence for this is a stream terrace at elevations between 590 and 610 feet a.m.s. For the last 4,000 years the base level of the river has stayed relatively the same, and lake levels have fluctuated by about two meters. The following Woodland (~3,000 to 400 B.P.) and Historic periods had a climate similar as present, with much less variation than during deglaciation.
The frequency of sites decreases from higher elevations to lower elevations. Younger sites are more common than older sites. Paleo-Indian sites occupy uplands near the Grand River and stream terraces. Archaic sites exist on the uplands near the river, and deglacial to middle Holocene stream terraces. Woodland sites are found on all pre-settlement surfaces. Historic sites exist on uplands and the modern flood plain. The high number of sites located on the uplands suggests that they should be the focus of future archaeological investigation. Most of the sites are associated with resource gathering and camps, while larger more permanent settlements were located on alluvial surfaces within the valley. The type of geomorphic surfaces should be considered in future studies.
Nathaniel Hansen , Patrick Colgan