Plunge Pool, Upper Jaw 2 Recovery

Wednesday, August 29, 2012

The team did not return to the site until Wednesday to give the site and surrounding area some time to dry after over two inches of rain Saturday.  Farmer John and Dave traded numerous text messages and phone calls Monday and Tuesday discussing the problem and possible solutions.  John finally located an electric generator from a co-worker and Dave borrowed a sump pump from the Indian Creek Nature Center (ICNC). Dave arrived at 8 AM accompanied by Jan Aiels from the ICNC.  They met Jim Roberson and were soon joined by Farmer John's neighbors Leanne and Shirley. The pit was quickly pumped dry but the water left a large quantity of muck that had liquefied and slumped under water, on the bottom of the pit.

Unlike the Tarkio Valley sloth site, which stayed dry after pumping, the mammoth site has sprouted a number of leaks both on the bottom and on the sides. Apparently, Saturday's rain recharged the ground water and flowing down from the western uplands it has found the path of least resistance into the pit.  One cannot dig long without stopping to bail out water--sloppy conditions will be a permanent challenge ahead.

Shirley recovered a portion of a vertebra while clearing the drainage ditch downhill from the discovery pit.  Jan recovered some skull fragments in the muck directly under where the tree had grown.  One piece still has roots attached. 

The team began extracting the ribs found the previous dig so they could renew their attack on upper jaw #2.  The team was joined at 1 PM by Indian Hills Community College Professor Lee Wymore and veteran mammoth digger Jenn, a nursing student and President of the IHCC Science Club.  The team continued extracting ribs, while making clean cuts on the pit walls in anticipation of the arrival of Art Bettis later in the PM.  Leanne discovered a new rib less than one ft. north of the main rib deposit and 6 inches higher, resting in clay rather than the gravel. It was left in place for Art to see.

UI Professors Art Bettis and Frank Weirich with graduate student Phil Kerr arrived at the site at 4:30 PM with the goal of determining the nature of the skull/rib deposit.  They scraped and sampled the wall. They also used a hand auger to collect samples, comparing their observations from Phil's notes related to the core they collected approximately 20 ft. west and uphill from the skull.  Art confirmed the importance of the tree that was excavated last week for marking the date of the slump.  He recommended collecting and saving any pieces of wood found directly associated with the bones to date the deposit with greater precision.

Art suggested that the bones may simply be sitting in a large block of slump which was undercut, broken apart and transported by a flood in one of the two ancient streams that bordered the site.  It is also possible the bones are sitting in a plunge pool created by the junction of the prehistoric Skunk River tributary that still runs east of the site and the prehistoric predecessor of the dry gulley coming down from the uplands overlooking the site from the west.  An ancient flood on the Skunk may have created a nick point which eroded uphill (much as occurred after the 1993 flood which ultimately exposed the bones) causing the bone-bearing deposit to collapse into the plunge pool.  This scenario would account for the large range of depth of the bones and the large angles from horizontal in which some are sitting. Art requested that as we move west we continue to take wide-angle photos of the sediments/walls and send them to him.   He asked if any of the diggers had a 35mm camera to take a high resolution photo of the west wall.  No one had one on them, but Osky News reporter Ken Allsup, who arrived with William Penn reporter Maureen McKamey at 5:30PM to interview Art, volunteered to come back in the AM to take the photo. Leanne extracted the rib she had found for the reporters and the team departed at 6:15 PM.