Advancing archaeology: Industry and practice in Alberta, 2019 ARCHAEOLOGICAL SURVEY OF ALBERTA OCCASIONAL PAPER NO. 39 Glacier Pass Concretions: A pre-contact toolstone from an alpine quarry complex in Alberta’s Rocky Mountains Todd J. Kristensena*, Timothy E. Allanb, Emily Moffata, Aaron Osickic, Dale Fisherd, Robin Woywitkae, and John W. Ivesd a Archaeological Survey of Alberta, 8820-112th St. NW, Edmonton, Alberta, Canada, T6G 2P8 b Tree Time Services Inc., #3464-78th Avenue, Edmonton, Alberta, Canada, T6B 2X9 c Archaeology and History Branch, Indigenous Affairs and Cultural Heritage Directorate, Parks Canada, 720-200-4th Ave SE, Calgary, AB, T2G 4X3 d Department of Anthropology, University of Alberta, Edmonton, AB, T6G 2H4 e Department of Physical Sciences, MacEwan University, Edmonton, AB, T5J 4S2 * corresponding author: [email protected] ABSTRACT A pre-contact stone quarry complex was recorded in the 1970s in Canada’s Rocky Mountains on the north edge of Jasper National Park and south edge of Willmore Wilderness Park, Alberta. Anderson and Reeves (1975) called the raw material Glacier Pass siliceous mudstone. We present geochemical and mineralogical analyses of the material including portable X-ray fluorescence, thin sections, and hyperspectral imaging. When combined with field observa- tions and modern bedrock maps, our analyses suggest the raw materials are best defined as concretions that formed around carbonate-rich nuclei. Concretionary materials presented challenges to flintknappers. Our results indicate that pre-contact toolmakers were aware of internal inconsistencies in concretions and targeted specific high silica bands that produced a better quality, predictable substrate for tools. Preliminary experiments demonstrate that the material responds well to heat treatment. Glacier Pass Concretions appear to have been reduced in situ to remove impurities and low-quality bands. Some of the remaining uniform, silica-rich portions may have been transported away from the alpine quarry complex to lower altitude regions for heat-treatment (with ready access to trees for fuel). We present photographic libraries to aid identification and summarize an archaeometry-based reconstruction of pre-contact cog- nitive approaches to a raw material seasonally exploited in an alpine area for several thousand years. KEYWORDS Concretions, mudstone, Canadian Rockies, pXRF, hyperspectral, alpine, hunter-gatherer, flintknapping 1. The Alberta Lithic Reference Project Some pre-contact lithic materials (toolstones) in Alber- 2018) in the Alberta Lithic Reference Project, the goals ta, Canada have been inconsistently identified due to a of which are to illustrate and analyse archaeological raw lack of accessible references with standardized nomen- materials used in the province, standardize terms, and clature and high resolution photographs. This is the fifth spur new research agendas. The current article explores in a series of articles (Kristensen et al. 2016a; Kristensen Glacier Pass Concretions (GPC) that were quarried for et al. 2016b; Kristensen et al. 2016c; Kristensen et al. several thousand years in Canada’s Rocky Mountains. 113 Kristensen et al. / Archaeological Survey of Alberta Occasional Paper 39 (2019) 113–142 2. Introduction: Glacier Pass Concretions Elliot and Reeves recorded a series of 20 archaeological Glacier Pass Concretions (GPC) were first identified in sites containing artifacts made from Glacier Pass siliceous 1970-71 by Jack Elliot and Brian Reeves at the east edge mudstone in an alpine subregion that extended from the of the Rocky Mountains (Figure 1) during an archaeologi- northern tip of Jasper National Park to the southern edge of cal inventory of Jasper National Park (Anderson and Reeves what is now Willmore Wilderness Park (Figure 2). 1975). The material was called Glacier Pass siliceous mud- stone, which occurred as nodules presumed to have eroded Anderson and Reeves (1975:117) thought cobbles (Fig- out of underlying shale (Anderson and Reeves 1975:117). ures 3 and 4) originated in mud beds via silica migration. Figure 1. Glacier Pass Concretions source area and North America bed- rock geology (data from USGS 2015). The dashed lines encompass the rough boundary of the Northern Rocky Mountains Range. Figure 2. Glacier Pass Concretions source area and Alberta bedrock geol- Figure 3. GPC cobbles from Willmore Wilderness Park. The majority of ogy (data from the Alberta Geological Survey, 2019). The boundaries of cobbles encountered are already naturally fractured, which would have Willmore Wilderness Park and Jasper National Park are in white. exposed the concentric bands to pre-contact knappers. 114 Kristensen et al. / Archaeological Survey of Alberta Occasional Paper 39 (2019) 113–142 Figure 4. GPC nodules are most commonly found in eroded secondary contexts in which rounded to sub-rounded cobbles have moved short distances downslope from bedrock outcrops that no longer exist. This process formed concretion-like nodules more resis- the raw material has remained largely restricted to a black tant to erosion than the shales that originally housed them. and white technical report (Anderson and Reeves 1975). The material was estimated to have been used in a localized north-south range because Glacier Pass siliceous mudstone Identifying this material has been hindered in part by had yet to be recovered in neighbouring valleys to the east broader inconsistencies about the interpretation of sedimen- and west. Very little was known about a broader distribution tary raw material types. Mudstones are generally defined as of the material because of the sparseness of regional archae- carbonate and/or silica-rich sedimentary rocks comprised of ological research. While a great deal of archaeological work a combination of fine-grained clay and silt-sized particles has since occurred along the eastern edge of the Rockies (the that were plastic (fluid) when wet and were often deposited Eastern Slopes and Foothills regions of Alberta), for exam- in active, organic-rich aqueous environments (Potter et al. ple, Brink and Dawe’s (1986) work in the Grande Cache 2005; Macquaker et al. 2007; Aplin and Macquaker 2011; area, our understanding of Glacier Pass siliceous mudstone Lazar et al. 2015). Rocks made of uniform clays are gen- has not significantly advanced because information about erally shales while rocks of uniform silt-sized particles are 115 Kristensen et al. / Archaeological Survey of Alberta Occasional Paper 39 (2019) 113–142 3. Portable X-ray fluorescence generally siltstones. The term concretion generally refers to a secondary structure (as opposed to parent material) formed X-ray fluorescence analysis involves the emission of by alternating diagenetic conditions (the changes that occur x-rays onto a surface to excite electrons from the sample’s when sediment is converted to rock). This process can re- atoms, which then exit their respective electron clouds. En- sult in the growth of concentric bands and layers of matrix ergy is released during this electron movement in the form or interstitial material within the host rock (McCorquodale of X-rays and beta particles; the quantity and wavelength of 1963; Pye et al. 1990; Chan et al. 2007). The distinction energy is diagnostic of the elements from which the elec- between mudstone and concretion is not always clear if a trons belong (Parkes 1986; Andrefsky 2005:44). An analyz- mud parent material gives rise to concretions (Astin 1986; er interprets and converts fluorescence energies into elemen- Scotchman 1991; Marshall and Pirrie 2013). We argue be- tal concentrations in absolute values. PXRF has been most low that the material at Glacier Pass developed into a knap- commonly used in archaeology to determine concentrations pable toolstone through the concretionary process and was of high energy trace elements in samples, e.g., rubidium targeted because of its visibility as concretions. That is, the (Rb), strontium (Sr), yttrium (Y), zirconium (Zr), and niobi- diagenetic conditions during concretion formation converted um (Nb) because they are easier to detect than low energy el- a carbonate-rich mudstone into a silica-rich material suitable ements, e.g., Si, Ca, Mg, Fe, and potassium (K). Recent im- for stone tools. For these reasons, we propose moving from provements in pXRF technology, including those employed the informal name of Glacier Pass siliceous mudstone (An- here, enable quantitative analyses of lower energy elements. derson and Reeves 1975) to the formal name Glacier Pass In particular, Si and Ca are important for differentiating Concretions. highly siliceous and poorly siliceous (e.g., carbonate-rich) sedimentary rocks, such as mudstone, ironstone, and chert The objectives of the current article are to: 1) Use portable (Williams 1994; Rowe et al. 2012; Thöle et al. 2020). X-ray fluorescence (pXRF), thin section analyses, longwave infrared (LWIR) hyperspectral imaging, and effervescence PXRF was employed for three purposes: 1) To determine tests to characterize the geochemistry/mineralogy of GPC the composition of Glacier Pass Concretions and inform and infer its geological origins; 2) Provide means to distin- their origins (see Croudace and Gilligan 1990 for XRF utili- guish GPC from local Alberta materials used in pre-contact ty on iron-rich rock); 2) To determine whether or not the ma- times to make stone tools using microscopic, macroscopic, terial has a distinct geochemical signature compared to other and geochemical analyses; and, 3) Summarize