Heat Treatment

[chase]

Chase wrote:

Now that's a great day. Without a size reference, but I dont think that's a Cobbs. The Tip will be hard to identify, but the material looks like it has been heat treated, which would eliminate a paleo point type.

rmartin wrote:

I agree with Chase on this. Cobbs are large beveled knives. Yours appears to be a very nice small knife but I wouldn't call it Cobbs. Hard to say on the broken one but as Chase said the hint of heat treating would eliminate Early Arcaic or Paleolithic.

Wilburn wrote:

Chase and Ray
I beg to differ. Some Paleo have been heat treated. Check this link of a great site (Crowfield) excavated by Dr Brian Deller. Five miles from where I live. This is just one site there have been more.anthropology.uwo.ca/cje/Crowfield.htm

chase wrote:

Wilbrun, Thanks for the link. I read over the Crowfield site. Here is what I took from it.
from: anthropology.uwo.ca/cje/Crowfield.htm

In all over 4500 heated artifact fragments were recovered, the vast majority of which seem to have originated in the major pit feature discovered. Refitting of the fragments revealed they made up 182+ complete Paleo-Indian artifacts which had not been broken in manufacture or use and it is clear they were deliberately burned. The large number of items recovered from the single pit feature, and the fact they were deliberately burned or sacrificed, suggests ceremonial activities and it is possible these pit items represent a cache of goods associated with a cremation burial. However, no organic remains were recovered because of the age of the site and the acidic soils which destroy anything other than stone tools and debris.

This is not heat treating, but more sacrificial. Heat treatment is done in a controlled rise in temperature to an extreme heat of 400 degrees plus over an extended period of time, and then slowly cooled. This is done to make the chert easier to flake. Thus the change in color to a pinkish hue. What happened at the Crowfield site was an extreme heat,with no controlled rise in temperature, on finished artifacts with no intent to heat treat. This would in fact, as stated, fracture the chert.
I hope that clarifies what the differences are.

Wilburn wrote:

Chase that might have been for sacrificial..however according to what I have read Paleo did practice heat treatment.
See quote: "Closer to the western New York area, heat-treatment has been fairly convincingly implicated for Palaeoindian tools and debris of Fossil Hill chert in Ontario (Pavlish and Sheppard 1983), and well documented for jaspers in Pennsylvania (Schindler, et al. 1982; Hatch and Miller 1985).
Given the apparently common prehistoric knowledge of the process and its geographically and temporally widespread usage",
Sorry dont have the link. I must have taken a screen shot of the article. The above quote does have a number of references in it.
Heat-Treating Experiments With Onondaga Chert: Preliminary Results*
Frank L. Cowan < Fcowan9115@aol.com>
(*This paper was written for a graduate course in ethnoarchaeology at the University at Buffalo, May 11,1987.)
I find heat treatment very interesting and at times frustrating as I have been trying to get to know the lithic sources and that sure can throw it off. Thanks for the feedback...love this forum. Only thing is we cant do this over a few beers or coffee!

acepro wrote:

I may sound extreamly stupid but please be pacient im new! hahaa...... I have two questions..
-why did they heat treat?
-how do I tell if it is heat treated?
thanks!
Beau

JoshinMO wrote:

Chase explains why heat treatment was used above, and sometimes when a material is heat treated it will change colors or shades.

[chase]

Wilburn wrote:

Chase that might have been for sacrificial..however according to what I have read Paleo did practice heat treatment.
See quote: "Closer to the western New York area, heat-treatment has been fairly convincingly implicated for Palaeoindian tools and debris of Fossil Hill chert in Ontario (Pavlish and Sheppard 1983), and well documented for jaspers in Pennsylvania (Schindler, et al. 1982; Hatch and Miller 1985).
Given the apparently common prehistoric knowledge of the process and its geographically and temporally widespread usage",
Sorry dont have the link. I must have taken a screen shot of the article. The above quote does have a number of references in it.
Heat-Treating Experiments With Onondaga Chert: Preliminary Results*
Frank L. Cowan < Fcowan9115@aol.com>
(*This paper was written for a graduate course in ethnoarchaeology at the University at Buffalo, May 11,1987.)
I find heat treatment very interesting and at times frustrating as I have been trying to get to know the lithic sources and that sure can throw it off. Thanks for the feedback...love this forum. Only thing is we cant do this over a few beers or coffee!

wilburn, I think this is the link your referring to on the paper written for the graduate course.http://wings.buffalo.edu/anthropolog...hermal-old.pdf
From reading this paper and the experiments on the Onondaga chert concerning heat treatment, this lithic seems an unlikely candidate.
And discussing this over beers does sound good. 

[chase]

acepro wrote:

I may sound extreamly stupid but please be pacient im new! hahaa...... I have two questions..
-why did they heat treat?
-how do I tell if it is heat treated?
thanks!
Beau

Those are both good questions! my smart as. answer is because they could. :laugh: and use your eyes. :laugh:
Really! all chert's are not created equal.The basic micro crystalline structure is some what the same, the other minerals effect how easy or tough the lithic is to work in knapping. (AND IF I HAVE THIS WRONG PLEASE JUMP IN AND CORRECT ME)Heat treatment greatly increases the work ability of the lithic. The color change is from the minerals and a molecular restructure of the micro crystalline structure. One of the most Identifiable chert's that has been heat treated is Burlington chert, as in a raw form its opaque white, when heat treated it will have a hue of pink to streaks and color changes to orange. Some chert's when heat treated may take on this same sort of look. The raw color and mineral make up will effect how the chert will look.

[acepro]

ah ok starting to make sence now thanks! do you think the orange on this piece indicates it has been fire?

[chase]

This does not appear to be heat treated, the yellow looks to be more of mineral in nature.
here is a few pic's of heat treated and not.


Heat Treated



Not heat treated.

[JoshinMO]

Just want to say heat treatment of chert in this area apparently started in Archaic times, and I mean late archaic but became much more common in woodland times.

[acepro]

  thanks Josh and Chase!  that clears alot up for me! love the photos chase as well. also another question... how common is it to find a "heat treated"  artifact???
thanks
Beau

[JoshinMO]

Quite common in certain areas.

[acepro]

when chase said that the stone works easier when fired does that mean the stone was fired before the flaking and detailing of the pont?

[JoshinMO]

Yes, mostly. They would make rough preforms, heat treat those and put the finishing touches on them.
Heres a video that explains more.

[rmartin]

First to qualify my response, let me say I am going on what I see in my area and my limited experience. Burlington is the primary material I find here in Central Illinois and what I am the most familiar with. White flint is definitely the easiest to tell when it comes to "cooking". It will turn the color to barely noticeably pink to a bright red. It will also add a gloss to it that will vary. Among the variables, are amount of heat, the amount of cooking time, the makeup of the material, and the preparation of the material. Heat treating, per say, is the preparation of raw material, not finished artifacts. I am no Knapper, but I have a friend that is and we have discussed this. Burlington is a nodular flint and how it is cooked has much to do with the outcome. I have witnessed nodules come out of the ground that when broken open show very little color change but are a little more glossy. I have also seen biface blanks come out brilliant red. As Josh said, in this area heat treating started sometime in the Archaic period. I have seen a few Middle Archaic pieces that were definitely done as such but in my area that is a culture that is not well represented. The earliest points I have found that were cooked were Late Archaic. Table Rocks are the ones that come to mind. This is a great subject and one I am very interested in so if anyone disagrees with what I have spouted, please feel free to disagree!

[tomclark]

[JoshinMO]

Tom, I have noticed Florida has some "tasty" looking chert! :woohoo:

[tomclark]

Especially when cooked!~

[dirt kicker]

If the Na's could cook rocks to perfection, imagine how good their venison black straps tasted. :lol: