Monday, January 27, 2014

Flake Tools and Deer Hide

Hi all,

The other day my friend Angela Gore shot an Axis deer near Fredericksburg, TX and brought the hide over to begin the fleshing and tanning process.  Angela is interested in Upper Paleolithic and Paleoindian archaeology focused on the peopling of Beringia and the Americas, specifically patterns of human dispersals, hunter-gatherer ecology, and human behavioral adaptation.

What's really cool is that she brought along a ton of raw chert local to the area where the deer was taken. This locally available raw material is commonly known as root beer chert and is a minor lithologic constituent of the larger Fredericksburg limestone, dolomite, marl, and chert group. High quality nodules from this group knap very well and offer a more durable alternative to obsidian.

Axis deer hide ready for work
Fredericksburg root beer chert nodules

 We decided to perform the task with local raw materials to see what it would have been like to process a deer hide as a Central Texas forager.  The abundant raw materials allowed us to use expedient flakes taken from a core to flesh the hide.  Informal tools are made when minor design constraints are present such that little to no reshaping of a flake is necessary to complete a task.  In an instance of raw material scarcity, our technological choice may have become centered around a more formalized flake core to preserve our stone.  In this case I created blade-like flakes (more than twice as long as wide) from a single-platform core and produced more as initial flakes became dull through use.

Flake core with parallel removal scars and partially fleshed hide

When lithic specialists think of hide processing we sometimes focus too much on formalized scrapers.  Formal scrapers are the most iconic implement, yet are only one member of a much larger tool kit.  Interestingly enough, for our task, sharp flakes comprised the entire usable assemblage for the initial stage of fleshing.  The scrapers that we tested did laughably little to separate the tough membrane from the hide.  Formal scrapers will play a dominant role in the next stage of scraping the residual tissue once the hide is salted and soaked.  Salting the hide removes fats and oils that decompose and lead to hair loss on the pelt.  In this way each step includes a dominant tool assemblage that plays a key role in the multistage process.  Overlap in tool morphology no doubt exists as trimming with sharp flakes will accompany the formal scraper use later.  As far as site formation process goes, the initial fleshing leads to the production and eventual discard of several large, sharp flakes while the ensuing hide scraping produces small retouch flakes as scrapers are resharpened.

Angela uses a sharp flake to cut flesh from the hide

Visible use wear on the fleshing flakes took the form of a dull continuous polish along the cutting margin with minor flakes removed to dull sharp areas that came in contact with hands.

This sharp curved flakes worked very well.  You can see residue along the working portion of the flake

All in all a very fun experience that reminded us both of the compound nature of tool production, use and discard during a single hide processing event.  Additionally the task helped to reinforce the usefulness of expedient flake tools and the importance of tailoring production techniques to raw material availability.

Happy Hunting!         

Wednesday, January 15, 2014

Oh, Snap! Obsidian Knife Breakage

Hi All,

I hafted the fluted obsidian knife from the other day and took it out for a test in the Piney Woods of Deep East TX.  I (unsurprisingly) did not manage to get a deer or wild hog this time.  I did, however happen upon a rabbit.  These rabbits have been a real hit at cookouts with the neighbors, no really.

The Test:

In keeping up with thrashing nice things, I used the hafted knife to process a rabbit in a similar method seen in the previous rabbit knife post. The materials used did not change: obsidian knife blade, antler handle and pine pitch glue.  Rather than keeping the cutting edge centered along the tool's cutting margin, this time I played with a slight bevel.  This was supposed to be used in a test of resharpening efficiency between beveled and mid-line margins.  I had misplaced my metal knife so i set out on another functional-recon experiment with what I had laying around.

Hafted knife with beveled edge created along lower cutting margin


Unfortunately, I had little chance to observe differences in beveled/centered cutting edge performance as the blade snapped during rib cage separation.  I had inverted the knife, using the curved edge in an upward direction to open the rib cage from the inside.  This task did not bode well for this specific tool.  The event was signaled by the broken blade flying across the workspace that left a spiral of blood stretched across the ground.  So...pretty cool to see actually.  Try it for yourself sometime as a party trick, no?

The catastrophe resulted in a strange hinge fracture that traveled from margin to margin and split the piece in half.  The crack initiated from the curved section of the tool as force was applied upward.  Bending stress increased upon the fulcrum created at the junction of blade and handle to a sufficient degree such that the applied stress overcame the performance capabilities of the tool.  The fact that this was a fluted knife may have something to do with the breakage, as the channel flake eliminated the typical lenticular cross-section that usually works so well under bending stress. 

Blade held as used during fracture.  Fracture initiated from top to bottom

Oblique distal view of vertical bending stress fracture


Is this type of breakage specific to knife use?  I have never seen a hinge fracture like this as the result of horizontal impact damage.  Perhaps this type of breakage is associated with vertical bending stress during butchering events.  More tests are needed, as usual, but his seems to be something special in the world of task-specific breakage patterns.

The following images illustrate how this piece broke.  I have found that inverting the image is a simple way to see flake scar patterns slightly better.  There are some great new imaging studies out there that are revolutionizing our ability to assess flake patterning.  Inverting the image colors on obsidian is a quick and dirty way to see a piece in another light, plus it looks cool.

Let me know if you have seen anything akin to this type of stress fracture.

Happy Hunting!  

Saturday, January 4, 2014

The Cost of Education

Hi all,

Shaping stone is a timeless language, each flake a word, each tool a statement of place and time.

At some point along the line I convinced myself that learning how to remove channel flakes (fluting) was a good idea.  If I lived near a large raw material resource this would be less of an issue as I could go destroy preform after preform while gradually learning the intricate process of creating a channel for hafting with a single strike.

The concept of channel flake removal is quite brilliant and usually accompanies other techniques that require a lot of practice to master.  In brief, a channel flake is a single flake removed from the base of a biface that serves to create a long, thin area for the haft to fit.  This method allows for a relatively robust point to be hafted into a usable dart.  Without this special type of haft preparation the projectile would simply be too thick and the weight of the stone point and accompanying (gigantic) haft would render the weapon delivery system physically inept.  I'll test that situation soon.

The ability to remove single flakes from the base of a point led to some absolutely fantastic lithic traditions.  Clovis, Folsom (my personal fav) and Cumberland points all used this method to varying degrees.  But what is the learning curve like? It can't be all that easy...but is it really all that hard?  The fact that we find fluted points means it is by no means impossible, and other modern knappers do it all the time.  On the other hand, we find channel flake failures all the time too so it can't be that simple.

Folsom preform with overshot from the Lake Ilo site, North Dakota. Photo:

In this test I set out to see what the learning process looks like.  Do my attempts at channel flaking mirror the artifacts we find in the archaeological record?  What of my failures, do they look like unsuccessful attempts visible archaeologically?  This is just the beginning of a long-term project to document the learning process for channel flake removal.  Most folks like to show the best products of their endeavors, as if the skill set became magically integrated within one's motor skill vocabulary.  Here we enjoy the process and observe the punctuated nature of success. So, here we go.

The Test:

I decided to try a few different point types that used the method of channel flake removal.  Specifically, i thought I'd try my hand at fluting Clovis and Folsom preforms.  As part of my job is to identify and describe Paleoindian sites in New Mexico, it is to my own benefit to produce and observe the kinds of flakes produced by these early foraging communities.  I used obsidian for most bifaces as the ease of flake removal is well suited to this sort of task.  I decided to not go overboard with the channel flake removal apparatus.  Take a look around the internet and you will find some methods that work well, like giant milled metal lever devices.  while a cool modern technological innovation, metal lever devices create assurance and steal adventure, grit and risk right away.  I wanted to see if freehand percussion would work sufficiently, given practice.  The answer is yes, by the way.  There are plenty of great ways to remove channel flakes and freehand percussion is just one method.


Creating a channel flake before trimming the point to final form saves time and energy.  There seems to be no good reason to spend time making a perfectly symmetrical point, then fold it in half due to a failed flute attempt.  Once the channel flaking strategy is a success then spend time on aesthetics.

My initial attempts resulted in catastrophe.  But, in time my failure has begun to mirror problems evident in the archaeological record.  Hey, at least I am failing correctly.  There has been some success though. Several channel flakes traveled well and thinned the biface into a usable item.  The channel flaking failures, typically when attempting Folsom preforms, carried too far across the surface and removed the opposite tip.  This unfortunately reduced the final size of the item.  Reduced length means less cutting edge, less material real estate to work with and ultimately translates to less blood loss on impact.  These factors are serious attributes when attempting to kill a large angry "something" with a rock.

Lessons Learned:

Read around and you will find that creating a convex cross section is key.  To little surprise, convexity in the preform turns out to be essential.  Just like blade removal from a core (see microblade posts) flaking some convexity into the preform creates a mid line for the channel flake to follow from base to tip.  Again, unsurprisingly, platform preparation is essential.  Experience suggests uncalculated hope offers little comfort.   I am still not satisfied with my platform preparation technique.  I have seen some fantastic examples out there and my method needs refinement.  A little thing called "mapping" is helpful.  By grinding the face to be fluted with a stone one can observe the most prominent area of convexity and build a removal platform accordingly and apply force from the most appropriate direction.  Things will continue to get better from here.  I'll be excited to keep working on this technique.  There are some real masters out there, check it out on youtube if you are interested.  Oh, and don't need a fancy metal flaking leverage jig to get the job done.

 Take a look at the images below to see how things are working out.  This is the start of something fun, we'll see how my technique improves over time.

Happy Hunting.

This raw novaculite was very plastic feeling and resulted in multiple step fractures
I decided to flute this knife blade

Here is the support method that I use for direct percussion fluting
Overshot flake on Folsom preform
and yet another
This channel flake terminated early when it hit a stacked area

Overshot result on Folsom preform
Let's keep this party going! Yet another overshot
Novaculite channel flake