The Copper of the Riverside Site: A Late Archaic Village and
Cemetary in Menominee, Michigan
A Documented case of Prehistoric America Copper Casting Technology
by E.J. Neiburger, Waukegan, Illinois
In 1967, Robert Hruska reported on an Old Copper site along the Menominee River near the Wisconsin- Michigan border. The Riverside site spanned over 1000 years and was a mixture of Old Copper and Red Ocher cultures with a small component of Woodland and Mississippian cultural elements. The main report appeared in "The Wisconsin Archaeologist" (48:3 p.145-261) and was one of the best written, exciting, informative and practical reports to enter the archeological literature (frequently suffering from chronically dull, unimaginative and marginally scientific wordy trivia).
The site was a combined cemetery (63 individuals) and village featuring cremations (full and partial), flexed burials and evidence of a culture rich in mortuary goods, exotic materials and prestige related artifacts often associated with young adult females and infants...a clear indication of one of America's first stratified (rich-poor) society. Many of the remains were covered with hematite powder (red ocher) which was found in approximately 52 burial pits. There were a substantial number of large double pointed, 8 inch long, blue-grey horn-stones found, along with the hematite, indicating an early Woodland-Red Ocher cultural presence.
C-14 dates of bone (human, dog) , wood and charcoal ranged from 1090 BCE to 70AD. Most dates hovered around 500-200 BCE. Dendrochronological dates were consistent with the 1270 BCE period. The site had been surfaced collected for years (producing hundreds of artifacts) prior to the 1956 and 1960 University excavations.
The lithics found included 62 Hornstone blades, 25 elongated points (3-4 inches long), the first obsidian found in this region (most obsidian comes from the north-west US coast area), 15 scrapers, 124 stemmed projectile points (many sized for arrow use), a well polished game ball, 16 triangular points (Mississippian), a winged banner stone, drills, a side notched elongated point (Osceola) and a whetstone.
Pottery included 35 fragments mostly related to Woodland and Mississippi period (grit and shell tempered; Black sand, Dana incised). Animal remains included a jaw from a white tailed deer, beaver teeth, two moose teeth, a dog, turtle shell and caribou antler.
At top Figure A. Collection of Riverside site Old Copper, including two crescents (ulus), awls and "ace of spade" knives.
Above: Figure B. Socketed and conical copper points from Riverside. Note the harpoon head.
This site was rich in copper artifacts (Figures A-H). So numerous was the copper that many skeletons and wooden implements were preserved by the dissolved copper salts.
There were 3 socketed copper points, one was 7 cm long and possessed a rivet hole in the socket portion(Figure B). There were 3 crescents of uniform shape and size (Figure B), 5 "ace of spades" points with one on a preserved wooden shaft (knife)(Figure A)), a 30 cm copper pike, 560 copper beads of three basic types (globular, small narrow tubes, large irregular)( Figures C,D).
Thirty copper awls, from 2.5 to 9.5 cm long, were found( Figures A,D). One specimen was found inserted into a preserved wooden handle which also possessed an imbedded beaver tooth making it a compound tool (Figures F,G). There were 21 conical points; some not completed (Figure E). There were two celts (7cm long) found in the village debris (Figure H), 3 needles, 6 small fishhooks , 3 toggle headed harpoons (FigureB), 6 flat points (Figure A) and a large number of partially worked fragments ranging from lcm to 6 cm in size (Figure E).
THE LARGEST COPPER FRAGMENT ...A CASTING
Most Old Copper artifacts were hammered (hot or cold) from naturally appearing float copper. There are exceptions. One of the largest copper fragments (R666) found at the Riverside site was a trapezoidal shaped, wrought worked (hammered) lump of copper 4.5 X 6.0 X 0.75 cm in size (Figure H, L). This artifact is very special. It was found in Feature 64 (Refuse pit) and matched several other copper fragments in color and corrosion/patina formation. It was not an intrusive burial. Upon X-ray examination (Xeroradiography) this artifact showed the round radiolucencies (voids) typical of gas bubbles in cast metal (Figures I, K). This artifact was melted and cast. Metallurgical analysis ( at 100X magnification using a NHOH peroxide etch) shows a flow field (melting, large grains) abutted to a wrought worked (hammered) area which was heat annealed (twinning, small grain size); a situation also indicating casting (Figure J).
This is the first clearly documented and culturally identified site associated with an old copper artifact showing a melting process of manufacture. Copper cannot be melted in a typical campfire (1200 degrees F maximum).
It cannot be melted by mistake (e.g. left in an open fire) or in a forest fire. It requires too much directed heat and attention. Copper must be melted in a forced air furnace requiring sufficient insulation and air under pressure to attain the approximate 2000 degree F casting temperature of copper. Note that copper melts at 1983 degrees F ( 1083 degrees C) but will not readily flow unless kept at a few hundred degrees hotter. Since copper is the world's second best conductor of heat (after silver) it will rapidly cool unless well thermally insulated. Naturally occurring float copper was formed by chemical precipitation in the geological past. It was not melted by magma. Later, glaciers scraped and spread the metal throughout the region.
At Riverside, there is no evidence of molds, furnaces, crucibles, tuyers (tubes for air flow) or other mandatory relics of high heat furnace technology though these items can quickly weather and disintegrate in the Northern Midwest climate. For example, sand or soil molds, pottery crucibles and wooden tongs will quickly dissolve after several heating-cooling cycles and a few years of winter. The only permanent evidence that now exists is this one casting.
This leaves an important question. Casting is a very efficient method of manufacture once you have built the furnace and other systems. If the ancients, at Riverside, did cast metal, why didn't they make more castings as we see in the Old World. If you can pour one item, you can pour a hundred. Was R666 a trade item made somewhere else.? Was it an abandoned experiment?
In the late 1800s and early 1900s many archaeologist-collectors recognized casting as one form of Old Copper relic manufacture. Though most Old Copper artifacts were wrought worked (hammered) only, a few showed casting voids, bubbles and flow lines consistent with casting. Unfortunately, most were surface finds and could not be associated with known archaeological sites thus knowing the related chronological age and culture was a mystery. Most archaeologists, and all modern texts, claim that Old Copper artifacts were never cast, since the natives did not have "that" technical capacity. Many archaeologists have based their reputations on this "position" and take its consideration as a personal insult and threat to their professional standing. It is too bad. Few scientists have analyzed (chemically, radiographically) the thousands of old copper artifacts found to date for evidence of casting.
The R666 copper fragment's metallurgic and radiographic analysis overturns this erroneous belief that natives did not have the technology to cast copper). This fact has irritated quite a few professional archaeologists who have created a unique form of fallout. I have experienced my scientific papers and presentations on this subject boycotted, editorially sabotaged and otherwise dismissed. The old copper expert Warren Wittry (now deceased) once threatened to "ruin" me if I published this data and set up academic ambushes, damaged specimens and worked actively to suppress any debate on the casting theory. As these old timers die off and are replaced by younger, more freethinking scientists, opinions may change.
Above: Figure F Copper awl in a well preserved (though warped) wooden handle. On the opposite end of the handle was implanted a beaver incisor tooth; a compound, "Swiss army knife" type of tool.
Above: Figure J. Metallographic micrograph (100X) of R666, the top left artifact in Illustration I. Note the large crystals of copper in the lower left (indicating casting) and compare with the small mixed crystals in the upper right portion of the frame (indicating hammering and annealing).
The Riverside site is a multi-component site. It is mostly 'classic' Archaic Old Copper and Red Ocher in culture (1000 BCE-200 BCE). It possesses some lithics and pottery from more recent cultures that settled in the same location. The 'classic' Riverside site is remarkable in the variety and quantity of copper implements ( about 700 pieces) found. The excellent state of preservation confirms the way many copper artifacts were hafted and used. It is unique in its apparent wealth of grave items, social ranking system (females extensively honored), emphasis on the infant young and metallurgic technology including melting and casting of copper. It was well excavated, described and the recovered remains now reside at the Milwaukee Public Museum.
Above: Figure I. Xeroradiographic plate of the copper described in Illustration H. Note the spherical porosity (dark appearing bubble-like voids) in the top left artifact (R666). This is evidence of gas bubbles having formed during casting. No other process could produce this kind of image except the melting of the copper.
Above Figure K. Magnified image of the Xeroradiograph of copper fragment R666 (see H,I,J) showing the multitude of round casting bubbles.
Above: Figure L. Magnified image of R666 cast copper fragment from Feature 64 of the Riverside site. (see H-K)
"Used by Permission of the Author"
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