Glaciers brought mountain to man (not really)

Dionisio Point, north end of Galiano Island. Main vlillage sites (DgRv 6) in central upper portion of image. Credit: Colin grier via NPR.

A couple of months ago you may have heard of an exciting new study on the sources of rock for making stone tools in the Salish Sea.  “Glaciers brought mountain to man“, the headlines said, affirming that archaeologists working on Galiano Island had found nodules of raw material, not yet worked into tools, from the Mt. Garibaldi area of the lower mainland.  If, like me, you have a rudimentary knowledge of Salish Sea archaeology, you probably leapt to the conclusion that the raw material would be from the Garibaldi obsidian source.  So, cool: the mountain moves to Mohammed after all.  But, despite my being fairly disapproving of both sobriety and thinking in general, sober second thought did have me wondering: is it even possible that glaciers carried raw material from Garibaldi to Gabriola?  And from the relatively small and isolated high-altitude obsidian sources to a prominent village site?  ” It was brought there by glaciers, conveniently, 12,000 years ago”, the article asserts – thousands of years past the local ice maximum.  It didn’t easily compute. Luckily I was emailing with one of the paper’s authors, Dr. Colin Grier from Washington State University, and he set me straight on how the new article came to have something of a misleading takeaway point, while shedding some light on his recent interactions with the press.

Example of tool made from fine at Dionisio Point. Credit: Colin Grier via CBC. grained volcanic rock

The study, by Adam Rorabaugh et al. in Volume 3 of the Journal of Archaeological Science: Reports, (Academia.edu link – requires free signup) actually asserts that fine-grained crystalline volcanic rocks (CVR), such as dacite and andesite , were available in the glacial tills near the Dionisio Point Village site on Galiano.  People could therefore pick up this useful toolstone locally to their town site.  It doesn’t actually attribute the source of these CVRs to any particular source, nor make any claims that Mt Garibaldi or Howe Sound rocks are present at Dioniso Point.  OK, so the takeaway was in some senses completely wrong.  Colin sent along a nice discussion of his experience with the media (while emphasizing how hard the reporter worked to get things right), and agreed I could post it here as an example of the interaction between archaeologists and the press:

He writes, “How it all unfolded is a bit of an object lesson in how little things can make a big difference when your research is headed for public consumption. Interestingly, I do a segment each Thursday in my Introduction to Archaeology class (Anth 230) at WSU in which I bring up news stories that were in the press that week (usually on the web) and deconstruct the language in which they are presented. Headlines like “Archaeologists discover Britain’s own Atlantis” (referring to a drowned Mesolithic site in the English Channel) get a contextualized analysis in class to show what the real story is behind the headlines, and how archaeological data and interpretations are conveyed to the public.

Mountain moves to Man: 24News.ca headline.

“First off, I want to state up front that the reporter (Terri Theodore at Canadian Press) was great. She was very interested in the study and actually did a wonderful job of conveying much about the context of the research. Her engaging writing is what got the the story its day in the news. I was particularly pleased to see that the Dionisio Point site and the amazing archaeological record there and throughout the Gulf Islands was highlighted as part of her story. There was no attempt at sensationalism in her approach. On the contrary, she worked hard to get things straight, and what went astray can likely be attributed to imperfect communication (on both her and my part) of some nuanced archaeological analysis.

“As for how it all transpired, she initially contacted me, having likely found the study in some science news digest she subscribed to. We had an interview over the phone, and she recorded that, so I was quoted in several places in the media story. That’s good. Quotes give you a chance to state what you want to state exactly as you want to state it. I didn’t see the story before it was released, as I was at CHAGS in Vienna when it hit the news. I should have probably requested an opportunity to proof it before release. In hindsight I’d recommend that for anyone talking to a reporter, as it gives you a chance to clarify and correct things. A few slight wording changes would have made all the difference.

“As far as the story itself, the idea of glaciers bringing rock to people (the “mountain came to man” headline) appears to be the hook that got the story circulating. The gender-specific language is curious, but probably used for the snappy headline alliteration, or to create a primeval feel. That the material is glacial till deposited “12,000 years ago” should really have been “by 12,000 years ago”, since the Strait was likely ice free by then. Small point, but one place where I could have been more accurate (I’m quoted there, from the phone conversation).

“A somewhat more substantial issue concerns the focus in the story on Mt. Garibaldi as the point source of Dionisio cobbles. I’m actually not sure where that came from. All we demonstrated was that non-local material of knappable quality was available to the residents at the Dionisio Point site. As a result, we need not invoke long distance travel as necessary for tool stone acquisition.

Location of Dionisio Pt relative ti Watt’s Point dacite ((Howe Sound) and Mt. Garibaldi obsidian source. Source: Rorabaugh et al 2015.

“Mt. Garibaldi and Watts Point are mentioned in our study (in the background section) as places that other researchers have previously identified as potential sources of some toolstone found in various areas of the Salish Sea. But we did not attribute Dionisio till material specifically to either of those point sources. We did not analyze any material or report any chemical assays of Mt. Garibaldi material as part of our study. Note Mt. Garibaldi is an obsidian-like dacite source (as I understand it), and we did not encounter any of that type of material in the beaches at Dionisio Point (though we have recovered some small pieces of Garibaldi obsidian-looking debitage from the house excavations at Dionisio over the years).

“Watts Point, also located at the southern end of the broader Garibaldi volcanic belt (but not the same thing as Mt. Garibaldi) is also identified in our study as a widely utilized source, and might have come up in the phone interview as a candidate source of some of the higher quality material we identified. Watts Point is a high quality, fine-grained dacite, and very knappable, and some of the Dionisio material appears qualitatively similar in character and appearance. But we didn’t compare the Dionisio material chemically to any Watts Point data either.

“So the punch line of the story — that the fingerprint of the volcanic till cobbles from Dionisio “matched” Mt. Garibaldi — is not what was demonstrated or argued in our study, and is probably a bit of a journalistic conflation of the study and some comments I may have made during the interview. Simply, the high silica content and fine grained nature of some of the volcanic cobbles and tools from Dionisio are suggestive of a high quality source like Watts Point. But we don’t in fact speculate much on source locations in the study (we will be doing a follow-up study on that though).

“Interestingly, we also show that people at Dionisio were selecting for higher quality material from the beach. Nonetheless, some of the highest quality material actually may have been brought from sources outside of the Gulf Islands. We leave that door open. So the  “men” may still have “gone to the mountain” at times. We can’t say for sure. But the point is that they didn’t have to. Accordingly, there’s no real “debunking” of any long-distance travel theory specifically (as one alternate headline to the story stated).

“The bigger picture, which I was able to emphasize in a subsequent CBC Victoria radio interview, is that having a local source of toolstone may have been another important element of sustaining village occupations over the long term. The Gulf Islands have long been thought of as a seasonal way station between the mainland and Vancouver island. But what I have been trying to demonstrate over the last two decades is that there was long-term, intensive and permanent settlement in the Gulf Islands for millennia. This actually came through somewhat in the original CP story (and I emphasized this point in the CBC radio live interview) — the archaeological record out there is amazing, and recent research is changing our view of Gulf Islands life over the last several millennia.

“”The use in the story of the term “treasure trove” (with its connotations of looting and artifact collecting) is probably not the best way to describe the data-rich Gulf Islands archaeological record, but I understand what was intended as far as meaning (note it is not a quote so I probably didn’t use that exact phrasing).

Dacites are characterized by increased amounts of silica relative to Basalt or Andesite. This increased glassiness makes them suitable for some kinds of stone tools, especially those requiring sharp edges and precision shaping. Source: Whitney Osiensky 2014 MA thesis. Click for thesis (PDF)

“Overall, it is really great that so many people have been talking about Gulf Island archaeology for a few days, and that it is not about Grace Islet. I’ve had follow-up inquiries from media from all over North America. I still am unsure why this useful but pretty modest XRF study made the news so expansively, especially compared to other equally (or more) interesting research of mine and many others. It was undoubtedly due very much to the journalist finding an angle that connected with many people. We need to embrace that, as we as archaeologists are not necessarily good at doing that. But we do have to recognize that journalists (and other non-archaeologists) may not see the subtle nuances of how we make our arguments, and when our arguments are directly data-supported versus exploring potential implications. So we have to be careful to shape the story as best we can. It is not like the rocks in the Dionisio beaches were described as coming from Atlantis or anything…

“An interesting and final note is that I’ve had to clarify with a few colleagues that, no, I haven’t discovered a source of Garibaldi obsidian raw material out there in the Gulf Islands. A careful read of the study clarifies that, but it does go to show that even among colleagues sometimes the main way we get our point across is in public soundbites rather than longer, peer reviewed venues. So goes the age of the internet and social media.”

So, there you have it – Rorabaugh et al. demonstrate a cool pattern of stone distribution with cultural implications and this is something that will inform future debates about mobility and trade in the Salish Sea, but if all you heard was the news reports then, like me, you got a fairly misleading and dramatic (though fun) misrepresentation of the actual findings of the study.  So, thanks to Colin for spelling out how the conversations went and clarifying the study implications for us.

Interestingly, this study adds to an emerging literature on non-obsidian sourcing of raw material in the Salish Sea.  See the recent MA theses by Whitney Osiensky and Kimberly Kwarsick in the references below, as well as the older dissertation from Bakewell.  At a site I’ve seen on Sidney Island, there is clearly a secondary source and quarry of fine grain volcanics in a morainal-type deposit.  It’s refreshing to see the range of possibilities being considered for stone tool raw material access – not only direct procurement, or trade, but also these secondary deposits scattered across the region.  A very different possibility but one I once explored in a different life and different country, is how people themselves can “lithify” the environment by creating artificial quarries of raw material nodules at different locales where they anticipate use.  In Argentina (PDF), this allowed expedient technology to be practiced in a rockless environment, giving insight into the organization of technology and the built environment of small scale societies.

References:

Bakewell, E. F. (2005). The Archaeopetrology of Vitrophyric Toolstones, With Applications to Archaeology in the Pacific Northwest. Unpublished Doctoral Dissertation, University of Washington, Seattle, Washington.

Kwarsick, K. C. (2010). Lithic Raw Material Procurement and Technological Organization of Olympic Peninsula Peoples. Unpublished Master’s Thesis. Washington State Uni- versity. Pullman, Washington.PDF

Osiensky, Whitney (2014) Thesis Title: New Method For Sourcing Fine-Grained Volcanic Artifacts in the Salish Sea: A Holistic Approach. Unpublished MA thesis, Western Washington University. PDF

Rorabaugh, Adam N. , Nichole S. Davenport, Colin Grier
Characterizing crystalline volcanic rock (CVR) deposits from Galiano Island, B.C., Canada: Implications for lithic material procurement at the Dionisio Point locality. Journal of Archaeological Science: Reports Volume 3, September 2015, Pages 591–602  Academia.edu Link.

Whidbey Island Clovis Point is made from Howe Sound Dacite – but probably from a secondary deposit. Source: Kimberly Kwarsick MA thesis p.71. Click for thesis (PDF)