The excavator and a bull dozer arrived at the Tarkio Valley sloth site at 8:30, Sept 19. The dozer then constructed a road for the excavator down to the top of the second slump block surface above the south bank of the Tarkio. The excavator skillfully worked across this surface, frequently building a working platform to remove about 12 feet of overburden, largely slump sediments, within six inches of the sloth level. A ditch was also constructed 15-20 feet to the south of the present stream to bypass the whirl pool about 20 meters downstream from the sloth bone concentration. The project was completed about 4:00 PM with most of the creek diverted into the new channel. It may be necessary to sandbag a small space upstream to completely close the old channel. Late breaking news. Dean informed me that a debris dam has developed at the upstream end of the channel behind a large log that lies just above stream level. He also noted that beavers apparently have a dam downstream in the new channel. The owner of the construction company that did the earth moving, Butch Mather, is aware of the problem. All associated with Mather and Son Construction have gone out of their way to be helpful. This should be resolved before next weekend. 
 
Observations: 
 
1. The sloth-bearing blue-grey surface exhibits rolling topography. This topography probably is a result of the 1993 flood that moved the West Tarkio from the south to north bank of the valley. A black muck, which clearly is reworked, usually is stratigraphically above the sloth layer in the cleared area. Thus, the sloth bearing unit is displayed as islands surrounding by the black muck. Coarse sand overlies the blue-grey clay on some of these islands and may correlate with the sand stringers entrenched into the blue-grey clay noted during the first excavation. The sand also is exposed on the unconformity above the blue-grey clay in the north wall of the first excavation. These islands, which seem to lie at sloth level, should be skimmed for sloth remains. 2. As noted previously in Megalonyx Matters, the present stream truncated the sloth level south of the rib cage and removed any bone present. If the bone was removed after formation of the whirl pool about 20 meters down stream, it probably is concentrated there. 3. Examination of the pool contents is the next priority. The bottom of the pool is rocky (and hopefully bony), at least on the upstream end. The next step will be to completely sand bag the north and south ends of the old channel to isolate the pool and pump the pool as low as possible. Volunteers will then pass rocks, bones and buckets of sediment to a screening area above the pool and remove the bone. The screens consist of ¼ inch hardware cloth with 1/8th inch hardware cloth baskets available to insert on the screen.  4. The much of the bone will be fragmentary. There were at least 46 pieces involved in the reconstruction of the left femur. All bone collected to date was fractured, probably by freeze/thaw, but the pieces remained in place facilitating repair. The good news is that the breaks are clean. 
5. The pool excavation probably will present a giant jigsaw puzzle to assemble over the winter. Bob Athen, Dean Tiemann, Dave Brenzel and Holmes Semken were present during this phase of the sloth recovery program. 6. The plant macrofossil sample did not contain any remains. The same is true, so far, of the microvertebrate sample taken from the sloth rib concentration. Two samples taken from the underlying blue-grey silt are still too damp to process. Jim Huber will process the pollen sample from the rib cage area in the next two weeks. 
 
Holmes A. Semken Sept. 26, 2003