Cranium and Retouched Tusk

September 6, 2012

Sarah, David and Holmes left Iowa City at 7:00 am and arrived at the site shortly after nine; road repairs required taking the scenic route to Farmer John’s, but Sarah’s GPS kept us on track. Half of the volunteers were already on hand when we arrived and had Jim’s pickup loaded with all tools needed for the excavation. The excavation area had three feet of water from seepage and a sump pump was employed to drain the site. A large portion of the woolly mammoth’s cranium, found under the previously removed palate, reappeared partially resting on a detached tusk as the water dropped. While the volunteers removed slop from around the bones, Sarah loaded GPS coordinates for exposed elements. Work then began to pedestal the cranium, difficult because of the tusk’s juxtaposed location. The cranium, lying sideways, was undercut on three sides and plaster bandages were applied with the idea of rolling the specimen into a topographic low opposite the tusk. Holmes then felt sinus box-work extending into the matrix below the cast. Further bad news occurred when the plaster on the tusk side failed to cure properly, probably because of local humidity. The specimen would be under a foot of water by morning so rolling the specimen to a safer area was the lesser of evils. The box-work came up with the specimen but fell out of the poorly cured portion of the cast as a single unit; it was stable. The tusk was then cleared, covered with wet burlap and rolled onto another board. The cranium was placed on a heavy blanket for handling and gently carried out of the excavation. The tusk was moved to Farmer John’s damp basement and the cranial element to his barn because it required five people to lift it. We decided not to move the specimens to the museum in Iowa City because President Obama was holding a pep rally beside the museum and the secret service had secured the building. It would have been a trying experience for both groups involved. Three ribs also were removed and several other elements, apparently ribs and a vertebra, were discovered and will be collected at a later date.

The geology at the site still is perplexing. Both the west (upstream) and east (downstream) walls of the excavation were modeled ‘smurfic’ blue and black and the downstream exposure contained a well preserved rib. The south (right hand) wall was composed of sand stringers in a much coarser grained matrix with plant fragments and bone at the same level of the downstream slump. This may be the wall of the plunge pool or creek deposits that cut the bone-bearing deposits. This bone-bearing deposit is four feet, three inches thick and deep enough to accommodate a standing rib (70°).  Cobbles are intermingled with bones of all sizes as if all items gently settled into the deposit. As noted earlier, there is no evidence of abrasion on the bones but dry fracture on some elements indicates surface exposure prior to burial.

Participants were Laura DeCook, Mike Goudy, Peter Eyheralde. James North. Jim Roberson, Lee Wymore, Mary Jane Sullivan and Leanne Van Donselaar.