Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Sociology, Social Work, and Anthropology


David Byers


Judson B. Finley


Jacob Freeman


The purpose of this study is to complement existing knowledge on prehistoric mobility in eastern and southern Idaho. I add specific detail regarding the use of Skull Canyon and its well-known Birch Creek rockshelters during hunter-gatherers’ logistical foraging rounds.

In addition, my research is a case study in combining debitage attribute analysis and intensive toolstone sourcing to read prehistoric mobility. Prior research has looked to obsidian toolstone sourcing to understand prehistoric eastern and southern Idaho mobility. However, no prior research has involved sourcing an entire, stratified assemblage of prehistoric debitage.

I collected flake attribute data from all 2,846 pieces of Bobcat Shelter debitage including both obsidian and microcrystalline silicate artifacts. I collected x-ray fluorescence, obsidian sourcing data on all 1,830 pieces of Bobcat Shelter obsidian debitage.

Analysis involved combining strata based on similarity in strata mean toolstone source distance. This was necessary due to strata sample sizing constraints. Mann Whitney U tests were used to find significant differences between groups based on every one of ten disparate debitage attributes. These attributes are expected to change in predictable ways with increasing mean toolstone source distance. Group median attribute values were used to verify predicted differences between groups.

Debitage characteristics appear dependent on distance from toolstone source. As expected, this is especially true for exclusively obsidian samples as 100% of significant Mann Whitney U results are associated with predicted trends in group median attribute values. Obsidian material deposited before the Late Archaic/ Late Prehistoric transition originates from farther geological sources than after, pointing to an important difference in mobility levels. This research also uncovers a large increase in the proportion of specific toolstone sources during the end of the Late Archaic (2,950 –1,650 BP), detail missed during less intense sampling of Bobcat Shelter sourced obsidian.