How to Make a Petroglyph

Replica sandstone petroglyph made by Christine Stathers. Photo credit: Stathers.

I’ve often said the graduate student work is the backbone of the archaeological discipline in British Columbia.  Today I get to report on more student work – but this time its a fascinating study done by an undergraduate student at Camosun College here in Victoria.  The student, Christine Stathers, did an experimental archaeology project for her Anthropology 240 course, and she kindly agreed that I could post some of the results here.  The results are highly informative for our interpretation of petroglyphs, I think.

Use of hammerstone (cobble chopper) to make a sandstone petroglyph. Credit: Christine Stathers.

I think there is a lot of received wisdom about petroglyphs and a lack of hard information.  Ethnographic accounts are thin on the ground, perhaps because these spiritual sites were not and are not the proper topic of discussion with Anthropologists, at least.  There is often no archaeological context for these sites other than the designs themselves: no datable material, no associated artifacts, no faunal remains, etc.  And one of the key questions when considering or weighing possible interpretations might be, how long did a typical petroglyph take to make?  If it took an hour or two, that might rule in or rule out certain genres of interpretation; if it took months that might also suggest certain cultural practices or contexts of manufacture.  Since petroglyphs are an archaeological site of wide public interest, of considerable cultural importance, and of little firm archaeological knowledge, then any steps taken to better understand their manufacture could pay dividends down the road.

With this in mind, Stathers set herself a simple task: make a petroglyph on a piece of local sandstone.  She tried a number of different ways of creating grooves, including abrasion and  indirect percussion, but pecking using a hard-hammer was far and away the most effective.  She reports on the various costs and benefits of her tools (illustrated below) and discusses her decision making process throughout.  Interestingly, the hard-hammer of choice was a basalt cobble-chopper she had made for this purpose – an idea which may have percolated down from Dan Stueber, when he was at UVIC doing lithic replication last summer and made some stone bowls with the students, also using cobble choppers. (Hi Dan, I owe you an email….).

Experimental lines and pits on sandstone. 1. Direct percussion, quartzite hammerstone; 2. Direct percussion, basalt hammerstone; 3. Direct percussion, antler hammerstone; 4. Direct percussion, slate hammerstone; 5. Abrasion with basalt; 6. Abrasion with identical sandstone; 7. Abrasion with coarse sandstone; 8. Indirect percussion, antler chisel; 9. Indirect percussion, land-mammal bone chisel; 10. Indirect percussion, sea-mammal bone chisel; 11. Indirect percussion, slate chisel; 12. Combined pit and groove technique, basalt hammerstone and identical sandstone abrader; 13. Direct percussion, small basalt hammerstone; 14. Direct percussion, sandstone hammerstone; 15. Hand-drilling, antler borer; 16. Direct percussion, antler hammer; 17. Direct percussion, quartzite hammerstone; 18. Hand-drilling, basalt borer; 19. Hand-drilling, slate borer.

Photos and Caption above by Christine Stathers.

The bottom line is the deeply pecked, well formed and elegant petroglyph at the top of this post was created in only one hour and fifty three minutes.  The basalt cobble-chopper-hammer-stone was resharpened twice.  As Stathers concludes:

Previous research on rock art of the Northwest Coast has focused almost exclusively on stylistic, functional and formal analyses of petroglyph images. Through experimental archaeology posing research questions regarding methods of petroglyph manufacture, a large amount of data could be added to this somewhat missing element in Northwest Coast culture’s very significant rock art traditions. Determining materials used and the length of time in which a petroglyph may have been created, insight into just who was actually creating these could radically shift the traditional ideas that petroglyphs were predominantly associated with spiritual activity and created exclusively by ritual specialists. A secular individual could just as easily create a deeply pecked petroglyph in fewer than two hours if he used a basalt hammerstone; this may explain the marked differences in style and skill seen within rock art sites. If not dramatically altering these large-scale perspectives, replicative approaches to petroglyph creation could at least aid in determining weathering patterns as part of determining relative dates within sites, and clarify the types of artifacts and debitage that may turn up in any excavation at a pre-contact petroglyph site.

This is impressive stuff for a 2nd year archaeology class and speaks well to Stathers’ initiative and to the mentorship of her instructor, Darcy Mathews.

Tools used in experimental program. Tools of different materials used in the experiment. A. sandstone abrader; b. quartzite hammerstone; c. slate borer; d. basalt borer; e. basalt hammerstone; f. small basalt hammerstone; g. slate chisel; h. basalt graver; i. antler hammer; j. slate hammerstone; k. antler borer; l. coarse sandstone; m. antler chisel; n. quartzite hammerstone; o. land mammal-bone chisel; p. fragment of sea-mammal bone chisel. Artifact (e) was used to create the replica petroglyph. Photo credit: Christine Stathers.

I’m going to make one little quibble – she rejects nephrite on the basis of a personal communication from Mathews (gotcha) that there is no evidence such material was used as a pecking stone or hammerstone.  In fact, Mackie (1992) explicitly illustrates an example of a ground stone celt which shows a battered and crushed edge really only consistent with use as a hard hammer on stone.  In the business, this is known as a “vanity objection”: good work but please cite the reviewer…..  On the other hand, this was the only celt in a sample of 1500 or so which showed this degree of edge crushing.

Crushed edge of a celt from the Victoria area (DcRu 65:2) consistent with use as a hard-hammer. Source: Mackie 1992 M.A. thesis.

26 responses to “How to Make a Petroglyph

  1. What a great project! Well done, Christine.


  2. Agreed! This is an excellent project by any standards. Any chance a copy of this paper/report might start to circulate?


  3. Thanks for the comments, T and T.

    If Christine would like & agree, I could upload and link a PDF of her manuscript. It’s certainly a viable, cite-able addition to the literature on petroglyph manufacture.


  4. Pingback: How to make a petroglyph

  5. Interesting results. And way to go Darcy for inspiring this kind of work in your class. Looks to me like a very good prospect for a publication in The Midden which would be more cite-able than a link to this blog, and useful for grad school applications if that is on her horizon.

    It would be interesting see maginified photos of the resharpening flakes from the basalt tool to see what the use-wear looks like, and to give some sense of the debitage that might be found in the ground near to petroglyph sites.

    I remeber seeing in your blog somewhere mention of the tools found near the petroglyph that is now at the Vancouver Museum. Perhaps in a contemporary newspaper article? Can’t find it now, possibly because there is so much about that petroglyph kicking around now. Anyway, did that reference not include some kind of chipped stone tool said to be for making the petroglyph?


  6. Thanks Quentin! What a nice thing to wake up to in the morning. If you’d had your masters online before recently, I would have known about the nephrite and included it, but no other sources had anything on it and Darcy thought I was already going over-the-top!

    I’ve been thinking about publishing this with a bit more work. Does anyone have any suggestions on how this might be possible?

    Quentin you’re more than welcome to post the whole thing in PDF form, if you think it might be useful to someone.

    ATM: I kept all of the debitage both from the tool-retouching as well as the flakes left over from the actual petroglyph manufacture. I, too, thought it might be interesting to see what kind of stuff might be found at this kind of site, should someone excavate one. There’s a lot of information I couldn’t include because we were limited to 2nd-year paper length.

    Thanks for your support, all.


  7. I also meant to add that Darcy is a fantastic instructor–most of the projects that came out of that class were very interesting and well-done. He’s very generous with his nerdiness and encourages those of us who are obsessed with archaeology (and who can sit and do one thing for up to 12 hours with intense focus) to indulge ourselves!


  8. Hi Chris and APM,

    The Midden would be a good outlet – a peer-reviewed publication would take a lot of ramping up and tightening, while The Midden bar is high, but a bit lower. Not to sound like a pufferfish or anything, but this blog has more and wider readership than The Midden I think it’s safe to say, but offers nothing in the way of credibility. People would find it and read it and could cite it as “Unpublished Manuscript” though – there is a whole protocol/stylesheet for citing online resources.

    Chris, let me know your thoughts. If you intend to submit to The Midden then it might be better not to put the whole thing up here – not sure. The ref. to my Master’s was meant to be jokey of course and I am not even sure that one celt was used on petroglyphs, in fact more likely it was used as a bruiser for making a hand maul or something.

    APM – you’re right, I think it was the contemporary news item re: the Lone Cabin Creek petroglyph, but I don’t think I posted it to the blog since I am not even sure where I got the news item from in the first place.


  9. I did see an article, and thought it was here, but it must have been attached to the site form, which is the only other place I have looked at for this site. Will have to have another look at RAAD and see if that is the source of my information.


  10. Found the source: Vancouver Sun, October 4th, 1925.

    “Near it [the petroglyph boulder] the prospector found a stone hammer, similar to those commonly found in collections of Indian curios. A small, sharply-pointed piece of flint was also picked up near the rock. Brown’s surmise is that the carvings were executed with flint, and hammer. The laborious process must have taken months to complete, he says.” This article and another from 11 months later are attached to the EhRn-4 site form.

    For those of you that missed qmackie’s earlier blogs on this petroglyph check out:


  11. It would be interesting if this possibly unique artifact(s) were still around. Since that petroglyph went first to Stanley Park then I’m not optimistic there is a “chain of custody” or any accession records about the artifacts that sound like they were picked up with it.

    Maybe the UBC student looking into improved conservation and repatriation of that petroglyph will find something out.

    The laborious process must have taken months to complete, he says

    Or maybe not (Stathers n.d.: 6) 🙂


  12. Very nice project! If Darcy was saying ‘this is over the top’ it would be the pot calling the kettle black.


  13. “The laborious process must have taken months to complete, he says”

    –Perhaps some of them did, though. Especially if he was using this “hammer” method. Any kind of indirect percussion, no matter the material, was absolutely useless and it would be a nicety to say “it erased the line drawn onto the sandstone”.
    I just can’t see this being a viable method of manufacture, having now tried it for hours.


  14. And there is the matter of the stone into which the petroglyph design is pecked; in my experience most of them are not made on sandstone. Methods might well vary for different substrate.


  15. For the Lone Cabin Creek account, it sounds like a “Flint” was involved, which is consistent with Stathers’ tool, though inferred to be indirect percussion. Though it could be coincidence or unrelated, or anything really.

    It is true that the Salish Sea petroglyphs are predominantly on sandstone, but elsewhere on the coast this isn’t the case. The massive petroglyph complex at [redacted] in Douglas Channel is all on igneous boulders if I recall correctly.


  16. That’s something I’d really like to check out in the future. It’d be interesting to really examine all of the surfaces of petroglyphs of all types too, provided that doesn’t harm them in any way.
    I believe weathering may affect sandstone too much to allow us to infer alot about their creative processes, but on harder rock that doesn’t erode as quickly, more information might be gleaned about how these were made through the markings left on them, if only apparent microscopically.

    It also might be interesting to examine closely the apparent methods of manufacture with the imagery and symbology, to maybe get an idea of whether or not there were artisans and laypeople.

    What do you guys think?


  17. I really like what you have done and appreciate your question regarding artisans & laypeople….As a graphic designer…..I often wondered what it would have been like….at some point….perhaps a realization that someone sensed they had a ‘knack’ for carving images into rock….not just lines and circles…though a round circle does take effort….but images that can be identifiable by fellow tribe members….perhaps these artisans would have had been considered sacred for their ability to take form from a thought and place it on a rock to communicate to others. I also wonder how much time it would have taken to make the same amount of markings onto a harder rock like basalt…such as the carvings at the Lagomarsino site near Reno, Nevada?


  18. The hidden nature of so many Salish Sea petroglyphs makes it seem more personal, somehow, but that is quite projective. Up coast, where petroglyphs might be right in front of villages more often, then the context of manufacture could be different.

    If we are talking artisans, then it might be worth thinking about stone-working specialists as much as petroglyph specialists — the latter didn’t produce a huge body of work for a few thousand years of specialization! Whereas all those hand mauls and stone bowls and whatnot may have required similar skillsets.

    I still lean, based on no evidence, but I think bolstered by Stather’s findings that the sandstone ones are not that hard to make, that these things were made by the people to whom they had the most meaning, and those were the people experiencing some kind of vision or transformative experience.


  19. Chris, the petroglyphs I have seen that are not sandstone are most often associated with water – on marine or river edges. (As qmackie says they are often in close proximity to residential sites which are commonly in such locations). As a consequence the images are often heavily water worn. I think that the chances of finding manufacturing marks are thus quite low in all but rare situations. Indeed, some of them are worn so smooth that they are very difficult to see now, even though they are carved into very hard rock.

    I think that there may be quite a bit known about manufacturing techniques in other parts of the world, such as Australia. There may be useful information from those areas that would be worth considering too.


  20. Previous research on rock art of the Northwest Coast has focused almost exclusively on stylistic, functional and formal analyses of petroglyph images.

    Not entirely true. Great work though.


    • Hi Nick Doe, thanks for your comment. I think you entered a web site when you commented and it looks like it got borked:

      Click to access Webp233c.pdf

      Alignment and geometry of petroglyphs at site DgRw 229

      Great article – I’ve been meaning to feature your web site for a while since I bought a few back issues of Shale Magazine last time I was on Gabriola.

      Here is a sample of the implications to enourage readers to grab that PDF:

      • these particular petroglyphs were not
      carved by an adolescent. They were
      especially not carved by an adolescent
      in a state of drug, hunger, or sensory-
      deprived confusion. They were rather
      carved by a mature and intelligent
      craftsman who was thinking very
      carefully about his design, and was very
      knowledgable about his physical
      environment and artistic traditions

      • no archaeological study is complete
      without an accurate survey and an
      accounting of the geology of the site.


  21. Wow, interesting, Nick!

    I wish I had seen this when I was doing the research portion of my project!

    Thanks for sharing that. Thanks, Quentin, for fixing the link.


  22. I just recently came across this post and thought i would add my 2 cents. Teit 1900:320 refers to a boys using ‘jadeite’ celts to peck round holes in boulders along the Fraser River. I have seen some of these, and they are always in ‘basaltic’ looking igneous boulders and would be much harder than sandstone. I would think that using a nephrite celt as a chisel would be an excellent method of quickly and precisely carving some of these petroglyphs into sandstone.



  23. I should also note, however, that i have not encountered any celts (out of ~1400 observed for my research) that had the obvious battering from working stone described by Mackie above.



  24. And most importantly I should note that this is an excellent research project – especially at the 2nd year level! A tip of my hat to you Christine.



  25. I am happy to come across this work as it may answer a question concerning can ancient rock art be considered to be graffiti. Was Christine’s work ever published? Can I get a copy of her research to study as a potential reference?


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