2007 Nevada Field School
Certainly the highlight of Week 3 was a two-day field trip. Our first destination was Bonneville Estates Rockshelter, which lies about 20 miles south of Wendover, Nevada. The shelter was formed by wave action during the highest stand of Pleistocene Lake Bonneville, some 15,000 years ago. Since Lake Bonneville receded from its highstand, sediments have accumulated in the shelter, reaching a depth of more than two meters. Humans have contributed to these sediments by building fires and bringing in plant and animal materials, but the bulk of the record reflects the rain of rocks from the shelter ceiling and dust blown from the saltflats several miles away. The site has been excavated since 2000 by Ted Goebel of Texas A&M University (and formerly of the University of Nevada--Reno), Bryan Hockett, of the Elko BLM, and Kelly Graf. Here, Ted is giving Hamilton students a brief history of the work at the shelter before we all descend into the excavation pits.
Here Ted is “reading” the layers from top to bottom to Maddie and Ceci. The uppermost layer is a compact zone of sheep dung which seals the underlying sediments. Descending toward the bottom of the deposit you pass 7000 years ago at about Ted’s midsection. The earliest human occupations, nearly 11,000 years ago, lie near the bottom. There appears to be about a 1500 year gap between the oldest cultural zone and the layer it rests on. This lower layer contains a few bones of extinct mammals, perhaps including American cheetah.
Kelly and Ted
This is a newly excavated portion of the shelter. The dark layer to the left of Ted’s lower arm contains two small hearths--thin concentrations of fire ash and charcoal. Charcoal samples from these hearths have been submitted for radiocarbon dating. These hearths lie in Stratum 18b, the lowest cultural layer in the shelter, and probably will return ages of 10.800-11,000 years ago (that’s radiocarbon years ago. When corrected, the actual ages will be closer to 12,500 calendar years ago). Notice also the fine layering in the wall behind Kelly and Ted. This complex stratigraphy mandates careful excavation technique in order to recover accurate data.
This will be a familiar sight to most archaeologists. Every bit of sediment is passed through fine-mesh sieves in order to recover even the smallest flakes of stone, tiny rodent bones, and bits of twisted cordage.