Around 10,000 years before the present, nearly 30 mammalian species disappeared from the North American continent. Included in these are the native American horses, a few species of camels, several types of large ground sloth, odd antelope species with horn arrangements differing from that of our present pronghorn, bears much larger than our present grizzly, sabertooth cats, and the American lion (larger than the current African lion). Almost all of these were large-bodied, and are often labeled the "extinct megafauna". This extinct megafauna included large proboscideans, like the various species of mammoth as well as the American mastodon, Mammut americanum.

A controversy has ensued over this megafauna extinction concerning whether it was due to climate changes at the end of the Pleistocene epoch, or hunting activities of the earliest native Americans. Evidence can be brought to support both of the hypotheses, and both may be at least partially correct. The resolution of this controversy requires careful analysis of skeletal remains, to ascertain the cause of death and to discern post-mortem modifications. It also requires multifaceted approaches to the analysis of the environmental context of the death assemblage, in order to test hypotheses involving an ecological cause for the extinction event. Thus the long-term goals of the research on the Calvin College-Ada Bible Church mastodon include careful evaluation of the skeletal remains, and their depositional environment. At the end of the summer 1999, the beginning of this long-term study was under way. 

Site overview looking north
 
 
 

Surveying the site

Site overview - May 1999, view to west

In May 1999, construction on a new driveway for the Ada Bible Church, located in Cascade Township, Michigan, revealed skeletal element belonging to an American mastodon, Mammut americanum. During the summer of 1999 a Calvin College team and community volunteers conducted an excavation and recovered all skeletal remain in the vicinity of the original finds. The geographic setting is a swale in an upland region supporting a pond in historic times. The mastodon remains lie directly on glacial till and are covered with a shallow organic-rich clay horizon resulting from pond deposition. The individual mastodon was a male in its later 30's at time of death. Approximately 50% of the skeleton was present; primarily from the trunk or skull regions. Portions of two feet; the left tibia +fibula; and the right patella were the only leg elements recovered. Most of the skeletal remains were badly fractured in situ and will require extensive repair and treatment. Bone material has been submitted for radiocarbon dating. A portion of the site will be covered this winter by the new roadbed, but excavation at the margins will be resumed during the summer of 2000.

• ~ 35 of a possible 40 ribs
• Left tibia
• Fragments of left fibula
• Left proximal tusk
• Right proximal tusk
• Numerous dorsal processes
• Numerous vertebrae
• Left lower jaw with molar in situ
• Portions of basicranium & palate with associated molars
• Right patella
• Most of the left fore foot
• Parts of the left hind foot
• Two tail vertebrae
• Parts of both scapulae
• Portions of the pelvis

* All elements have been severely cracked and/or fragmented due to the weight of farm equipment and construction machinery. Restoration will take a minimum of two years.

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.

* An examination of the Holocene stratigraphy and paleoecology of the site is currently underway as a graduate thesis project by Mischelle Julien at Michigan State University. This study should include a pollen analyses as well.
* Microvertebrate analysis of sediments taken from the site will be conducted in collaboration with Karel Rogers of Grand Valley State University.
* Following further bone reconstruction during the 2000-2001 years, a taphonomic analysis will be attempted examining bone destruction/preservation and the spatial distribution. This will be done in consultation with Daniel Fisher, University of Michigan Museum of Paleontology/
* Some further excavation of the area will take place in subsequent years but currently no definite plans have been made concerning the details of this phase.