Project Summary
The excavation site is located on old farmland located southeast of Grand
Rapids in Ada, Michigan. The land had been purchased by the Ada Bible Church
to be the location of their new building. Construction of the main driveway
began in the spring of 1999 but was soon halted when a construction worker,
looking for a drainage pipe, saw a shiny object in the ground. He stopped to
examine it and realized it was a very large tooth. The worker contacted the
Ada Bible Church site engineer, Sam Tawney, who then contacted the Calvin College
Department of Geology & Geography. Two Calvin geologists, Ralph Stearley
and Jim Clark, went to the site and were able to identify the tooth as that
of a mastodon. The identification was later refined by Daniel Fisher of the
University of Michigan, as the lower left molar of an individual aged 35-40
years. Based on diameter and taper of tusk material, the individual is interpreted
as a male. The Ada Bible Church staff realized the importance of this discovery
and were willing to postpone construction of the driveway for the duration of
the summer. Dr. Stearley agreed to supervise the excavation. He quickly assembled
a small excavation team comprised of Calvin College Geology and Archaeology
undergraduates and recent graduates. The project was also greatly aided by many
volunteers from various academic institutions and the community.
Work began immediately as a survey of the area to be excavated. A grid pattern
was superimposed over the site which was used for mapping bone spatial disposition.
While the surveying began others did a surface overview looking for bone material
and tusk fragments that had been disturbed by the construction activity at the
site. The construction company had removed a minimum of one foot of sediment
before noticing the tooth, leaving many of the skeletal elements exposed or
barely beneath the surface.
One problem the project endured was the consistent tendency for the site to flood with each rain event. During the summer of 1999 it rained frequently. The solution was found in a gas-powered pump that was used to remove water from all low-lying areas and excavation pits.
The excavation was conducted throughout the summer as weather conditions permitted.
All recovered elements were cleaned and stabilized in the lab prior to any reconstruction.
Skeletal materials were greatly fragmented and leached. Considering the poor
condition of the bones, some areas were excavated in block form, so that an
entire section (less than 1m square) could be sketched and then brought to the
laboratory to be excavated in a much more controlled fashion. Most excavation
was done using popsicle sticks and paint brushes, to minimize abrasion to the
bone. All skeletal elements were photographed in situ with a digital camera
during excavation, as well as mapped in the field. By the end of September,
all skeletal remains in the vicinity had been removed. These amounted to approximately
50% of the individual mastodon.
Fine-scale stratigraphy was undertaken by Calvin College undergraduate Beth
Vanden Berg in collaboration with Deanna Van Dijk, Geomorphologist at Calvin
College, and Mischelle Julien, Soil Scientist at Aquinas College. A back-hoe
was used to dig two trenches along the perimeter of the site, aligned on its
north-south and east-west axes. Each trench was approximately 25 meters long
and 1.5 to 2 meters deep. Numerous sediment samples were removed from the trench
walls and analyzed in the lab at Calvin. Cores were also taken throughout the
site to confirm correlation of units in areas a trench could not be placed.
The stratigraphic analysis confirmed that the sediments underlying the mastodon
remains were glacial till, deposited during the retreat of the latest Wisconsinan
ice sheet. Holocene organic-rich paludal sediments surround and overlie the
skeleton. The Holecene paleoecology of the site area is now in the early stages
of investigation by Mischelle Julien, as part of a graduate thesis at Michigan
State University.
Untreated bone material in reasonably good condition was submitted to Geochron Laboratories, Cambridge, Masssachusetts, for radiocarbon dating. The date returned was 3400 + 130 years B.P. The sample is believed to be contaminated with organic carbon from the surrounding sediment, based on a 13C of -28.