Old Dirt - New Thoughts

The 2007 Council for Minnesota Archaeology Symposium was held this weekend. Archaeologists from around the state (including a few of our friends from across the border) met to hear papers on recent research and cultural resource management issues. One of the big events was a presentation on the Walker Hill Site by Thor Olmanson, Mathew Mattson, and Colleen Wells. They really provided a great service to Minnesota archaeologists by presenting their findings even as their analyses continue. Perhaps the best part of their presentation was the chance to see in person the Walker finds and to hear the assessments of these finds from different archaeologists. Although I didn’t take a poll, there were clearly a range of opinions with many archaeologists unconvinced of the site’s cultural reality.

The paper presentation by Thor and colleagues provided many important details about the site setting, stratigraphy and lithic finds. The lithics were recovered from beneath a relatively thick (40 cm) deposit of aeolian sand. The lithic bearing horizon varies across the site. In some places it is a gravel lense and others it is a water-sorted sand deposit. The researchers were convincing in their argument that the lithic bearing horizon was an intact and sealed deposit, unlikely to contain significant mixing from upper soils.

They note that the site sits on one of the highest land surfaces in the area, and some distance from water (this is northern Minnesota though, the land of 10,000 lakes, so it’s hard to get too far from water). The glacial geology maps they showed indicate this setting was at the “confluence of a lot of glacial activity”. Given this geological complexity, it is not surprising that a variety of cherts, chalcedonies, jaspers, siltstones and other lithic materials are locally available.

The Walker finds are mostly pebbles, 2-3 cm in diameter, with some edge flaking. Thor and colleagues suggest these were scrapers, possibly used in the manufacture of wood and bone tools. (I believe this interpretation is based on edge morphology and not use-wear analysis.) There are no formal tools in the assemblage, no bifaces (although at least a few items have bifacial modification on an edge), and overall very little diversity. I looked at a number of their recovered flakes, including several jasper taconite flakes found in close proximity to each other, but saw none that appear to be from bifacial tool production or retouch - with one exception. The exception is a small flake of Hudson Bay Lowland chert that had multiple dorsal flakes scars and a distinct striking platform. I would not hesitate to identify this flake as cultural if I had found it while surveying for sites.

This small flake highlights the most obvious issue with the Walker Hill site - the essential absence of any indisputable artifacts. The question raised in the discussion following their presentation was why did the site’s occupants not manufacture any formal stone tools? Humans all over the world at this time were making exquisite bifacial and blade tools. Clovis, Dyuktai, Solutrean, even Chesrow complexes all include many items of indisputable human origin. The researchers’ reply that the Walker Hill occupants may have relied on bone and wood projectile technology because of the poor quality of northern Minnesota lithic materials is unconvincing given that later occupants of the region manage to chipped some decent tools from these same crappy rocks.

Perhaps the most pressing question I heard raised yesterday had to do with the geological context of the lithic bearing horizon. The water-sorted sands and gravel lenses identified by Thor and colleagues suggest fast flowing water formed these deposits. The key question is whether the modified lithics are coming from the aeolian soils or the fluvial soils? A high energy, flowing water environment could be the real culprit behind the Walker Hill materials and not some intrepid hunters living on the glacial margins.

My final thought on the Walker Hill site is that despite the impression made by recent press accounts, Thor and colleagues are approaching their investigation with due caution and skepticism. They are inviting the critical review of professional archaeologists, geologists, and other specialists. And they are marshaling multiple lines of evidence (soils, phytoliths, micro remains, etc) so that the question of the Walker Hill finds will eventually be answered to the satisfaction of most of us.

Although the Walker Hill discussion was of obvious importance, there were several other presentations that I found very interesting. Issues related to cultural resource management was a common theme in many of the papers, including the need for greater collaboration between archaeologists and local government planning agencies, improved site location data, and greater access to electronic records.

Kent Bakken’s presentation on lithic raw material use was the only regional analysis from the first day of papers. Kent’s presentation represents a major revision to his extremely useful, encyclopedic raw material paper from 1995. His new model on chronological patterns in raw material use offers considerable insight into changes in settlement patterns, territorial boundaries, and social interaction throughout Minnesota prehistory.

One comment made by Kent, almost in passing, needs further consideration by Minnesota’s archaeology community. Kent’s study clearly required an enormous data set drawn from the work of many different archaeologists and research programs. His comment that raw material type was the only attribute he found consistently recorded, however, suggests that a similar regional approach to the study of other data sets would be nearly impossible if based on existing records. I think Kent’s study illustrates the potential of a regional approach to archaeological analysis, but we as a community need to have a lengthy conversation about data standards, terminology, and open access to records if we want to expand beyond lithic raw materials.