Skip to comments.Science explains ancient copper artifacts
Posted on 06/13/2011 12:42:39 PM PDT by decimon
Researchers reveal how prehistoric Native Americans of Cahokia made copper artifacts
EVANSTON, Ill. --- Northwestern University researchers ditched many of their high-tech tools and turned to large stones, fire and some old-fashioned elbow grease to recreate techniques used by Native American coppersmiths who lived more than 600 years ago.
This prehistoric approach to metalworking was part of a metallurgical analysis of copper artifacts left behind by the Mississippians of the Cahokia Mounds, who lived in southeastern Illinois from 700 until 1400 A.D. The study was published in the Journal of Archaeological Science in May.
The researchers were able to identify how the coppersmiths of Cahokia likely set up their workshop and the methods and tools used to work copper nuggets into sacred jewelry, headdresses, breastplates and other regalia.
"Metals store clues within their structure that can help explain how they were processed," said David Dunand, the James N. and Margie M. Krebs Professor of materials science and engineering at Northwestern's McCormick School of Engineering and Applied Science and co-author of the paper. "We were lucky enough to analyze small, discarded pieces of copper found on the ground of the excavated 'copper workshop house' in Cahokia and determine how the metal was worked by the Cahokians."
Two materials science and engineering students conducted much of the research. Matt Chastain, a Northwestern undergraduate at the time of the study, worked alongside Alix Deymier-Black, a graduate student in the materials science and engineering department. Chastain, first author of the paper, undertook the metallurgical analysis of the samples, supplied from ongoing excavations at Mound 34 in Cahokia. Chastain followed up his analysis by volunteering at the excavation site.
"We cut through some samples of the copper pieces and polished them to look at the grain structures of the copper with a microscope," said Deymier-Black, second author of the paper. "From the size, shape and features of the grains inside the copper, we determined that the coppersmiths were likely hammering the copper, probably with a heavy rock, then putting the copper in the hot coals of a wood fire for five to 10 minutes to soften it and repeating the cycle until they had created a thin sheet of copper. "
After using basic metallurgical science to better understand the methods the Cahokians used to create copper sheets, Deymier-Black and Chastain recreated the metalworking process in the lab with natural copper nuggets, fire and a heavy stone ---pounding and heating the copper into thin sheets.
The researchers also tested theories that some archeologists had made about the coppersmiths' techniques. One idea was that they made large copper pieces, like ceremonial breastplates, by "laminating" sheets of copper together through a hammering technique. Deymier-Black said that the lamination could not be reproduced, even with much greater weights achievable with a modern press. The other hypothesis, that the Cahokians used copper knobs or copper rivets and other mechanical devices to secure sheets of copper together, seems more likely.
Another puzzle was how the Cahokians cut the hammered sheets of copper into regular shapes. The researchers cut replicated hammered sheets by four different methods: grinding an embossed ridge, shearing with scissors, hammering against a sharp corner, and bending the sheet back and forth. Only the bent edge looked similar to the edge of the historical artifacts, indicating that the Cahokians most likely used that method to cut copper.
Scientific insight into the process used to create the sacred copper artifacts of Cahokian people is helpful to James Brown, professor of anthropology at Northwestern Weinberg College of Arts and Sciences and John E. Kelly, professor of anthropology at Washington University in St. Louis. The two researchers, co-authors on the study, are credited with pinpointing the location of the copper workshop at Cahokia.
"I'm delighted that through the scientific process we were able to confirm some of the techniques and end some disputes about how the copper artifacts were made," said Brown, also an international expert on Native American archaeology. "This study gives some of the real details, so that an observer can imagine how it was done and could possibly hook onto other kinds of observations about the people of Cahokia."
In for a pound ping.
“From the size, shape and features of the grains inside the copper, we determined that the coppersmiths were likely hammering the copper, probably with a heavy rock, then putting the copper in the hot coals of a wood fire for five to 10 minutes to soften it and repeating the cycle until they had created a thin sheet of copper. “
Say what? What did they think they had a foundry? Rock science indeed!
They musta been happy when we introduced trains and pennies.
Wow....Who would have thunk!!
"international expert" ? I guess that's important since we AI's traveled the globe and established prehistoric American Indian colonies.
The modern plague of American Indians - archaeologists & anthropologists.
I wonder if these two clowns got their Phd’s for this awesome study? What is next, how flint arrows were made?
Flint arrows was yesterday.
This would be an excelent doctoral thesis project. The whole point is illuminate something new.
It’s got to be better than trying to come up with a new doctoral thesis on Shakespear.
There is no native copper in the Cahokian region. Presumably it came from the deposits in Upper Michigan, showing that long-distance trade was going on in those days, when there were no highways or railroads. Really remarkable.
I was under the understanding that most archaeologists wouldn’t even admit that Indians used copper to make weapons. This is the first I’ve read of this.
I don't know but this doesn't mention weapons, anyway.
“showing that long-distance trade was going on in those days, when there were no highways or railroads. Really remarkable.”
No highways - just the Mississippi, Missouri, Ohio & Tennessee rivers, and then Lake Michigan itself, - just to mention a few non-highways that were well traveled “back in the day”.
Most of what I read before on this topic seemed to represent one of two extremes - they couldn’t have done it themselves, or they had some fantastic science/knowledge modern people don’t know about.
That makes this report actually modest and sensible. At last.
· join list or digest · view topics · view or post blog · bookmark · post a topic · subscribe ·
Bronze Age Forum
Excerpt, or Link only?
· Science topic · science keyword · Books/Literature topic · pages keyword ·
Gee whiz. When my husband was a freshman at Northwestern Engineering school in materials science, he made 2 hammers. I still use them.
The scissors part was odd - but it seems they switched to matal fatigue, which is entirely believable.
Ha! Looks like a little cross-contamination from another article I was reading at the same time.
Some days I wonder about myself.
Some days I wonder about myself.
I'm not much of a believer in multitasking. An older wisdom was to do one thing at a time and to concentrate on what you're doing. I occasionally pay a price for defying that wisdom.
Still other artifacts, from earlier cultures like the Hopewell, had symmetrical holes cut in the copper and could not have been made by bending the metal back and forth. One that comes to mind is a serpent's head knife or spear point. I do recall seeing "rivetted" peices- overlaped plates wth flared copper pins through them that looked like repair jobs.
I think the reporter just grazed the fringes and didn't dwell much on detail.
There's a pretty good coffee table book called "Hero, Hawk and Open Hand" which has photos of some really remarkable artifacts from American prehistory.
I am surprised they didn't try #5, etching/scoring the sheet with moderately deep cutting-line, using a sharp piece of (most likely) crystalline quartz, then bending. That gives a line of weakness, and makes it easier to bend without distortion of the sheet.
Also, pounding with stones doesn't sound like a very high quality finished sheet. hardwood (or less likely, heavy antler) mallets, with a hide facing, OTOH, takes longer, but gives a better finish.
Personally, I think my first "project" would be to make a copper hammer & anvil!
Keep in mind that the Cahokia city was contemporay with the large cities in Arizona, the Chaco culture and the Phoenix basin.
The peoples of the east, knew and traded with the west. The Southwest cities traded with the cities to the south. Thus, there was wide spread commerce that crosses the artificial present border with Mexico.
The key fact un mentioned is the source of the copper. Did it come from Tennessee or from Arizona?
Aside, I use the same technique of forging and annealing in my studio today. I have a little rolling mill that eases the hammering task and a gas torch for annealing and don’t use stones.
Also, before bending, a line, even a curved line can be scored with perhaps a flint to assure the break along a desired line
Good thoughts - you ought to send them to the authors of the study. Every analysis should include “Next steps...”
What amazes me about so many of the myths about ancient civilizations and their erection of giant edifices is some sort of “lost technology” or “how amazingly smart the ancients were”, are most often given as the reasons they could do what they did.
The myths ignore the ancients’ ‘secret ingredient’ - unlimited slaves to yoke into their glory-seeking projects and no respect for human life, no matter how many had to do die to make their monuments possible.
“The Southwest cities traded with the cities to the south. Thus, there was wide spread commerce that crosses the artificial present border with Mexico.”
Well, I have read that linguists find links in some southwest tribal languages to very ancient precursors to both their languages and some languages south of the Rio Grande - suggesting very ancient migration from north to south.
But, in terms of contemporaries of the peoples around Mexico City such as the Mexticas and the later Aztecs, their social and “civilizing” sphere of influence is documented to NOT have extended much more than a couple hundred miles north of Mexico City. Suggesting some trade with north of the Rio Grande? Yes. Wide spread? No.
So please site some evidence of the “wide spread commerce” you speak of.
“The key fact un mentioned is the source of the copper. Did it come from Tennessee or from Arizona?”
The likely source for the copper used at Cahokia (southern Illinois) is the ancient large copper deposits in Michigan. The “highways” for that trade would have been the great river systems of the Midwest - the Mississippi, Missouri, Illinois, Ohio and Tennessee rivers.
......So please site some evidence of the wide spread commerce you speak of......
The reference is “The History of the Ancient Southwest” by Stephen H. Lekson. This is an excellent book that deals with the history of the Anasazi, the Hohokem and the Mogollon peoples that had large populations and cities in the Colorado Plateau, the Phoenix basin and the highlands in between.
They were contemporary but separate societies and were also contemporary and known to trade with the folks at Cahokia.
His thesis is “Every body knew everything” and “Distance was not a problem”
You are correct in the people of our south west were not Aztecs but they knew of the societies further south and there was trade.
Stephen Lekson has spent his dues time in the field and his work gathers all the work of the southwestern archeologists from the beginning to the present and connects the dots. Most south western archeology work is site specific and the investigators concern themselves with their own little patch of dirt. He takes a much broader scale in both time and distance in pulling it all together.
His book consists of about 250 pages of narrative and another 250 pages of notes. He writes in a very unstuffy manner and is a joy to read. I have been reading about the area for years and find his book to hands down be the best.
I didn’t see anything in the article saying what objects they were making. That would be interesting to know.
"...sacred jewelry, headdresses, breastplates and other regalia."
To me that means ornamental shtick.
“This is an excellent book that deals with the history of the Anasazi, the Hohokem and the Mogollon peoples that had large populations and cities in the Colorado Plateau, the Phoenix basin and the highlands in between”
What you site is a study that suggests “widespread” inter-tribal trade across the southwest and north of the Rio Grande.
You suggested, in your original comment, that the widespread trade was with groups south of the Rio Grande.
I continue to contend, as I said, the tribal groups in the southwest and north of the Rio Grande, had awareness of and contact with groups far south of the Rio Grande, but THAT contact did not constitute “widespread trade” from north to south of the Rio Grande. The vastly more correct “widespread” thesis is ACROSS the southwest, north of the Rio Grande, as study you cited suggests.
I wonder how long it would take to figure out quenching heated copper would make it more resistant to bending (tempered) versus slow cooled copper (annealed). Even a stone chisel might have been on my list as well.
I must admit I often find it amusing when academics try to sort out tradecraft...
Think about this. In order for the great pyramid to be built in 20 years they would of had to set a rock every 90 seconds. Stop and think about the logistics of that. Oh and no way were ramps to the top used. They would of taken more material than the structure.
“There is no evidence that the pyramids were built by slaves. In fact the evidence seems to be the opposite.”
“Think about this. In order for the great pyramid to be built in 20 years they would of had to set a rock every 90 seconds. Stop and think about the logistics of that. Oh and no way were ramps to the top used. They would of taken more material than the structure.”
The archeologists find evidence, and then they make conjectures, guesses and suppositions of what the evidence means.
The only factual part of their evidence is a city of laborers positioned appropriately for the laborers who most likely built the pyramids. As to the social standing of those laborers, the archeologists conjectures about there status is just that, conjecture - or maybe wishful thinking when considering (a)how frequent and commonplace was slavery in Egypt, in many forms, (b)how what the royals admitted as their own was how many slaves they could command, for whatever royal purpose they sought, and (c)how the Pyramids were not build to “produce” something that could gain anyone but the pride of the royals, and therefor the likelihood of the labor involved being freely given is a politically correct modern guess - based on what? - that they wanted to feed their laborers well? That’s nuts.
Lastly your suggestion of “ramps” and such is your suggestion, not mine; however your “20 years” period of time is also yours and not supported by most scholars.
All I suggested, was that of course when you have the means to command as much labor as you want, to build an edifice to your own pride, you can let the project take as long as it takes and command whatever portion of your population needed to do it. In one form or another, it always involved pressed labor at the Royal command, in societies where the Royal command was not disobeyed.
Egyptologists believe that the pyramid was built as a tomb for fourth dynasty Egyptian Pharaoh Khufu (Cheops in Greek) over an approximately 20 year period concluding around 2560 BC. Initially at 146.5 metres
I will no longer challenge your preconceived notions with facts.
Have a good life.
No, you are grossly misinformed. The Rio Grande has nothing to do with the trade routes across Arizona and New Mexico into the south.
You are behind in your studies. The incidence of trade with the south is well known and documented.
I gave you the reference. It can be delivered to you in just a few days........ read it
Yes, the copper comes from Michigan, but can be found along prehistoric trade routes that extend all the way to Charleston, SC, and down to beyond Valdosta, GA during this time frame. Also, ceramics from the Savannah River area can be found up near Michigan. The same exact people lived in at least two sites on the far opposite ends of that trade route, with more found every year....They got around...
What?! Modern plague of Native Americans? I beg to differ, and take offense to that... So would many, many modern tribal councils. Archaeologists are the last hope that many tribes have to recording their ancestral heritage before it is destroyed by all of us. WE get one shot at trying to find what is there, before the land gets blown up. And, most sites found are only 25% excavated, as is the Federal guidelines. NO sites get 100% excavated, which is sad in so many instances...Wanna point fingers at who destroys what? Scream about Walmart...they bulldoze whatever is there...prehistoric graves, paleo sites, mound complexes, paleo point manufacturing sites, historic cemetaries, etc...pay their environmental fine for not completing the mandatory survey required by the Federal government, and build a store that makes up for the loss in one week. Wanna put a stop to destruction of our history? Start by not shopping at Wally World anymore...
Anyone who shops there both indirectly supports modern terrorism, and the destruction of American Indian heritage...Now who’s at blame?
You are preaching to the choir. I know what Walmart (and others) have done. When the diggers are there to investigate the past they must respect those that are still here. For some peoples, those that have gone before should not be disturbed. At times those practices too much celebrate death when the living people would gladly share their history.
We all have opinions. Knowing what was done to my Nation/tribe, to my family in the name of: science, progress, assimilation, the greater good, etc., has helped to form my opinions.
“The Rio Grande has nothing to do with the trade routes across Arizona and New Mexico into the south.”
I think we might have a difference of what is meant when we say one term - “the south”.
So, say what its is that you mean by “the south”.
“Egyptologists believe that the pyramid was built as a tomb for fourth dynasty Egyptian Pharaoh Khufu (Cheops in Greek) over an approximately 20 year period concluding around 2560 BC. Initially at 146.5 metres”
1. That - 20 years - is an opinion, not a fact.
2. No one elected “Egyptologists”, or any self-appointed group claiming an exclusive membership thereto, to speak for everyone who has studied the question.
3. And, there are other learned opinions that disagree with that opinion - “20 years”. The “20 year” time frame does not begin from official ancient records in Egypt but is instead based on guesses about possible construction methods, calculations of the work-effort required for those efforts and then backing into another guess about how many workers “could have” achieved that particular effort in a given period of time. Altogether, that does not construct a fact, but a mere opinion.
The south would include western part of current Mexico and certain larger cities in central Mexico.
Also the time line is say 700 AD till the Spanish conquest and of course nothing was continuously static.
Again I would invite you to read the book. It is fairly recent and incorporates lots of recent ie since the 90’s results that cast different light on events
Amazing. I knew that certain types of stone which were prized for making tools were dispersed by trade over wide areas. Shells from coastal areas ended up far inland also
Over night a thought occurred that is significant.
When you read about the Spanish early trips north to search for Eldorado, you can note that they traveled the ancient trade route north that ultimately led to the pueblos. Their guides took them north on these well worn routes.
Also, on the subject of this thread, they were led far to the east and gave up and returned. Although they did not know it, the goal was Cahokia. There was an old memory but unlike the southwest, the people and cities along the Mississippi were all gone.