STONE AGE TECHNOLOGY AND ESTIMATING THE AGE OF SUCH ITEMS

I joined the US Navy in 1944 and was sent to Boot Camp at Great Lakes, IL, just North of Chicago.  This was the first time I had been outside the state of Florida since moving there from Louisiana at age 2 years. Some of my shipmates from New York and other big Northern cities soon picked up on my rustic ways and I was asked more than once what people did for amusement in those small jerkwater towns where, as rumor had it, many of them rolled up the sidewalks after dark.  This attitude was a bit puzzling to me because I couldn’t recall ever being bored for a lack of something interesting to do.   Boot Camp was, as intended, very stressful with many demands being imposed on the body and spirit at all times and when the occasion did arise when I could fantasize about being allowed a few days off when Boot Camp was over, visiting my favorite arrowhead hunting grounds was a high priority item.

Figure 1.

Gainesville, Florida, my hometown, could never be mistaken for a jerkwater, but it was usually a pretty sleepy place.  The main industry was the University of Florida, but there was also a creosote plant and a mattress factory and a couple of lumber mills.   Beer was available on tap and in bottles, but the county was dry so far as legal whiskey and wine was concerned.  Illegal supplies of these beverages were readily available, however, at premium prices and from a number of suppliers.  The main entertainment centers in 1944 were 3 air conditioned indoor movie theaters downtown and 2 drive-in theaters on the outskirts of town.   A couple of  “Night Clubs” with live dance music, beer and dining were also in business outside the city limits.  These were required to close shop around midnight, perhaps as late as 1AM.  They were decidedly very far above and beyond my limited budget.

Hanging around with my buddies, Snubby Bailey and Billy Hartman mainly, hunting for arrowheads and camping out with them was my first choice for entertainment when I had a few hours or more to spend in idle pursuits.   I also managed to see a movie on many Saturday nights.  There were times when we would leave our jobs at 6PM on Saturday, ride our bicycles to one or another prime hunting ground, and set up a camp nearby with a tarp, bedrolls, firewood, beans and coffee.  We could hunt for arrowheads until dusk, around 8:30PM, and then ride back to town to catch the last picture show after 9:30PM.   The newsreel, cartoon, and short features, plus the main event would usually last until around midnight.  But we were young and foolish in those days, so when we returned to our camp we would build a fire and put on a pot of coffee and shoot the bull until perhaps 2:30AM.  There was no alarm clock in the morning, except a distended bladder, and the sun was usually high in the sky when we finally got up and made breakfast.  A can of beans and the leftover coffee was more than adequate.  Snubby usually had major chores to do at home, like mowing the lawn, and he went to the evening church services as well, but there was plenty of time to walk up and down the furrows if we were camped near a farmer’s field or to make a serious pass over the open ground wherever we happened to be. 

My parents were quite accustomed to my random comings and goings and we could usually transact whatever business we had between the time I came home late Sunday afternoon and bedtime.  On many occasions I would have time to wander into the backwoods near my home before sundown.  The scene did not change very much over time, but I always found it interesting… the water level in the swamps and the canal… the birds and snakes and other creatures.   I was always on the alert for snakes and arrowheads back there, but unless the earth was free of vegetation there was little chance of finding artifacts of any kind.  There was a network of fire-gaps, deep furrows perhaps 8 feet wide made by a tractor, throughout the forest and I have several choice specimens found while wandering along these trails.  In time my buddies and I came to believe that almost any bare patch of earth as large as 5 acres or more anywhere in Florida would yield at least some evidence of Pre-Columbian human habitation to our sharp eyes.  (See row 2 items 5, 6, 7, 8, &9.  Item 13 row 2 was found by my mother in her garden… the only one found there… after she had farmed there for 20 + years).

My interest in arrowheads began when I was around 5 years old in 1931 - 32.  My folks had recently moved to the place that was to be my home until I joined the Navy in 1944. This place was roughly midway between Gainesville and Fairbanks, some 6 miles down the road toward Waldo.  It could fairly be said that we lived “out in the sticks”.   Our nearest neighbors lived ¼ mile away across the Waldo Road and the railroad tracks.  On our side of the road our nearest neighbors were roughly a mile away.  The terrain on our side of the road was a mostly pine forest and palmetto thicket with half-a-dozen cypress swamps, each covering perhaps an acre or two up to some 20 - 30 acres.  The Little Hatchet Creek drained the forest and the largest swamps into Newnan’s Lake, some 3 miles to the East.   A network of canals had been dug to facilitate the drainage of the smaller swamps into the creek.   The purpose was to minimize the amount of standing water in the swamps and thus the breeding grounds for mosquitoes.   However, judging from the size of the swarms of mosquitoes that were always present, I would guess that the effort was wholly ineffective.  But, of course, I had no way to compare what the situation might have been without these measures.

In any event the pinewoods and palmetto thickets near home and the canal through my mother’s garden were exciting places to explore.  One day while walking along the top of the ridge beside this canal I saw a large white object about 5 inches long, pointed and very symmetrical, on top of a dirt pedestal about 2 inches above the surrounding earth.  The heavy rains on the sandy soil tend to produce such formations around any hard object.  I had no idea what it was, but I was very excited to find it.  I picked it up and ran for home as fast as I could manage.  My father told me that it was an Indian Arrowhead and that the Indians, who had once lived hereabouts, made them of stone and used them for hunting game.  He went on to explain that the Indians were very wise in the ways of the forest.  They knew all of the habits of the wild animals there and made their living by hunting and fishing with only the most primitive tools and methods.  I was very excited by his description of the Indian way of life and I thought that I could want for nothing more than to live as they did in the backwoods and to learn all about the fish and the habits of the wild animals.

(I no longer have that first arrowhead, but for an idea of what it was like, look at No. 7 from the left in the 2^nd row from the top in the picture, Figure 1.)

In time I gained total access to the backwoods and the creeks and I was always on the sharp lookout for another arrowhead, but it was perhaps 2 years before I found another one.  I had better luck finding petrified shark’s teeth in the Little Hatchet Creek, as I have described elsewhere.  See

www.smecc.org/r_m_r_finding_the_age.htm

In the meanwhile my father found work as a surveyor on the Florida Barge Canal project.  There he found a dozen or so arrowheads as well as a number of beautiful limestone fossils.  I shared these treasures with Mrs. Carl Stengle.  Her husband was a larger-than-life gentleman who owned the flying school and a grass landing strip for light aircraft across the Waldo Road from my home.  When I wasn’t fishing in the creeks or the deeper holes in the canal or potting about in the woods, I was generally hanging around with Carl and/or his employees and the student fliers.

Once when I was roughly 8 - 9 years old Mrs. Stengle took me to the University of Florida museum with my shoebox full of arrowheads and fossils… all in packing material to keep them from rubbing against each other.  She was very encouraging with regard to my interest in science and hoped that the people at the museum would inspire me further.   I learned, instead, that arrowheads were “as common as dirt” and all but worthless to archaeologists.  Likewise the shark teeth and the fossils.   One of the archaeologists mentioned in passing that things might be different if, somehow, it was possible to tell how old the arrowheads were.  But, alas, there was simply no way. 

An old man, one Richard O’Malley, a friend of my family, had told me that the shark teeth were known to be roughly 25 million years old.  Geologists knew this, he told me, from studies of the layers of sediment.  The rivers and streams washed mud and silt down to the ocean every year, he said, and it settled out on the bottom of the ocean.  Then, after millions of years, the ocean bottom was forced upward in places forming the dry land, like Florida for example.  Then the yearly floods washed out new channels for the Little Hatchet Creek, and we could clearly see the various layers in the banks of the creek.  The monstrous teeth, as large as O’Malley’s hand, I had found in the nearby gravel beds was further proof that this place had once been at the bottom of the sea.

The lack of enthusiasm shown by professional archaeologists with regard for my arrowheads and fossils did nothing to dampen my interest in them.  The arrowheads were, to me, pure works of art while the shark teeth and limestone fossils were also things of beauty and a reminder of the Age of The Earth and the Grandeur of Time.

Duke Baer was Carl’s foremost flight instructor and my strong mentor for several years in the late 1930s.  He was very alert to events in Europe and while many of the adults I knew were in favor of “Peace At Any Price” with regard to Europe’s War, The Duke saw that our involvement was inevitable and there was no time to be lost in preparing for it. One time I was walking with him near the hangar when I found a beautiful arrowhead where he had just missed stepping on it.  I gathered it up and expressed great excitement over the find.  The Duke was less than enthusiastic and he used the occasion to give me a serious lecture regarding vital matters.  The reason, he said, why we never saw any of the people who made such artifacts was that Stone Age technology could not compete with modern machinery.  People like us, who had guns and airplanes and all the rest, had essentially wiped out those who could not adapt.  Now we were up against people in Germany and Japan and elsewhere who were dead set onto wiping us out with their advanced technology, and we would surely go the way of the Indians if we didn’t rise up to the challenge.  The Duke said that he didn’t know any worthwhile person who was interested in rocks.  Flying and engines and lubrication and weather and navigation and everything to do with flying was where the action was.  Those who devoted their time to such matters would be the winners while those who spent their time with rocks and fossils would be the losers.

A few days later I swapped all of my arrowheads and fossils to Jimmy Tyler on the school grounds and got in exchange a crystal set radio with headphones and a number of car parts that he and his brothers had filched from an auto-wrecking yard near their home.  The radio did not work at first, but after considerable fiddling with it I eventually managed to hear my brother play with The Orange Grove String Band over the local radio station.   A few days later I was sick over my foolishness, but that was like crying over spilt milk and I soon moved on.  I never held this misfortune against The Duke, perhaps because I knew that he had only my welfare in mind, but also because he still had a lot to teach me that I very much wanted to learn.

Some months later I was walking along the dirt road toward the hangar to visit The Duke when I saw a large arrowhead some 40 ft away on the ridge of earth across the ditch beside the road.  (The present day passenger terminal at the Gainesville Municipal Airport is very near the place).  The ditch was full of water and heavy blackberry thickets on both sides made getting to the artifact a non-trivial problem.  I went along the road until there was a break in the obstacles and made my way back to the spot.  

Figure 2

This piece, Figure 2, was a little over 4 inches long and the point was unusually sharp when I picked it up.  By the time I made my way back to the road a backwoods dirt farmer I knew slightly came along and asked me, “What you got there, boy?”  “Arrowhead,” I answered.  “Lemme see that,” he said, holding out his hand for it.  I handed it to him.   “Naw, boy.” He said, examining the piece, “that’s a Devil Stone and them’s bad luck.”  With that he slammed the piece against his ax and threw the pieces into the woods.  Then he went on his way.  I was mad as hell, but I was only 11 years old and not able to do anything about it. 

I was vaguely familiar with this backwoods superstition, but over time I came upon a fuller explanation of the matter.  Another version held that arrowheads were formed where lightening struck the ground and might even be a magnet for further lightening strikes… certainly bad luck for the holder, if true.  Still another bit of lore told how they marked the spot where The Devil had made water.  The Devil was also widely given credit for prehistoric fossils, like the dinosaurs, etc.  There were many who believed that the Earth could not be much older than 4000 years.  A famous Minister and Bible Scholar had once determined the exact moment of creation based on Bible accounts, including the lives of the descendents of Adam & Eve where the “begats” are listed.  Those devoted to this account believed that The Devil planted prehistoric fossils and arrowheads for men to find with the intent of inspiring them to reject outright, or at least question, the Biblical accounts of Creation.

I scoured the pinewoods and palmetto thickets where this man had thrown the pieces of my arrowhead at every opportunity.  I finally found one piece a month or two later and when I examined the broken cross section I was electrified by what I saw.

Figure 3.

The center of the broken section, see Figure 3, was a light purple color while all around the surface area the color was a pale brown to a more or less uniform depth of roughly one millimeter.  It seemed extremely likely to me that the whole artifact had been this purple color when it was new.  I had no idea how color in stone came about and my first idea was that water, or something, had penetrated the surface and somehow bleached out the color.  I also considered another possible effect based on my folks ongoing firewood project, both for their own use and for sale to others.  They rarely, if ever, cut down a living tree because there was always one or more in the woods near our home that had been killed by lightening or blown over by high winds.  My mother and father would cut one or more of these trees into stove wood length blocks using a crosscut saw and then split the blocks to the right size using an ax.  They would then assign to me the task of stacking the sticks in an open structure for the sun and wind to dry.  I had long since noticed how the sticks from the center of the tree were always noticeably wetter than were the sticks from the outer edges.  I attributed this to the outward migration of the sap, mostly water, and the subsequent evaporation of the moisture into the atmosphere when it reached the surface.  Perhaps, I guessed, whatever is responsible for the purple color in my arrowhead is likewise migrating to the surface and either being washed off there by rainwater or simply evaporating into the atmosphere.  In any case, the appearance of the lightly colored strip of more or less uniform width around the outside surface took a lot of time, and the wider the strip, the longer the passage of time since the surface was created and the tool was new.  If I could ever figure it all out, perhaps there was a way, after all, to determine the age of arrowheads.  I fully realized that such a project was far and away beyond my capability at the time, but perhaps that would not always be the case.  I put the piece of the arrowhead away in my room until, a few months later, I found the other half.  Other matters took precedence for me now and this arrowhead was put away and almost forgotten.

I started hanging out with Snubby Bailey and his friend, Billy Hartman, around the time I turned 13 years old.  Mr. & Mrs. Bert Reames had recently taken me under their wing as an apprentice in their typewriter repair shop and I soon learned that Snubby was a dishwasher at the coffee shop 2 doors away.  I knew Snubby before this because my sister had a room in his mother’s boarding house.  Now we had frequent occasions to meet in the common alley behind our places of employment.  Billy Hartman was in Snubby’s Boy Scout troupe.  I joined the Scouts as well in response to Snubby’s urging and the 3 of us started hanging out at Snubby’s house, before and after Scout meetings at first, and then on a more regular basis.   Snubby’s older brother was an Eagle Scout and Snubby was intent on this goal as well.  In order to move up in the ranks, one had to earn merit badges.  One way to earn a merit badge was to make a collection… stamps, coins, leaves, insects, butterflies, seeds… almost anything.   

To make a long story short, the 3 of us eventually fell into arrowhead collecting and camping out on our own, without any involvement of the Boy Scouts.  Snubby was still in the habit of documenting his collecting projects and urged the practice onto Billy and me… with only limited success.  Said documentation included making a 3 x 5 inch file card for each artifact identified by number and with an account of when and where the artifact had been collected, an outline drawing, and any other relevant particulars.   Years later a college professor harangued me into resuming the practice and for a very short while I tried, but I was too busy, or uninterested, or whatever.  By this time I had recovered the item in Figure 2. and scribed #325 on it in sequence with my effort at the time, but the numbers on my arrowheads are completely meaningless.  Even at my age, 77, I remember finding almost every one I own, the place, the time, the circumstances, the weather and such, even though my short term memory is the pitts these days.  I’m not at all sure what a card file catalog could do for my heirs or their successors in ownership of my collection.  Hopefully this account of my interest in the age will be useful.  Who knows?    Sorry ‘bout ‘dat… but not very sorry.

After a couple of years scouring the farms and vacant lands around the edges of Payne’s Prairie we were always on the lookout for new hunting grounds.  One time a fellow high school band member invited me to go fishing with him on Biven’s Arm… an appendage of the Prairie, in his boat.  Rowing around the far side from his dock I saw a patch of ground, perhaps 5 acres, adjacent to the water and almost devoid of vegetation.  I had never been to this part of the countryside before and reckoned this place to be an ideal hunting ground for artifacts.  As soon as I had the opportunity I went to the land registry and looked at the maps and ownership records there.  There was a 2-rut dirt road that I had never noticed before off the highway leading back to the place.  I rode my bicycle there and met an old man sitting on his porch who answered to the name listed in the registry.  I told him that I had noticed his farm while fishing on Biven’s Arm and, with his permission, I would very much like to see if I could find any arrowheads there.  He was quite talkative and seemed to be very grateful to have someone to listen to him.  “Yup,” he said, “we used to call ‘em ‘Thunderbolts’.  What makes ‘em is where lightenin’ strucks the ground.  Yup.  I used to turn ‘em over with the plow all the time when I started farmin’ here, but I ain’t seen one in years.  Them University Professors used to come out here all the time and pick ‘em up.  ‘Thunderbolts’ is what they used to call ‘em.  Where lightenin’ strucks the ground is what makes ‘em.  But I ain’t seen one in years ‘cause them University Professors done been out here and done got every one.  You can go on back there and look if you is a mind to, but you ain’t gonna find none, ‘cause them University Professors done got every one.    ‘Thunderbolts they call ‘em.  That’s ‘cause they’re made where lightenin’ strucks the ground.”

I thanked him very much for this information and walked back toward the water.  Some 100 – 200 feet from his house I found the item shown here in Figure 4.

Figure 4.

I found several more pieces there that day, halves and fragments, and over the next year or so over a dozen whole, or almost whole, arrowheads as well as numerous fragments and a number of potsherds.  I rarely saw the old farmer on these visits and I never shared these finds with him because I had no desire to show him up as wrong in any way.   I noticed right away that one wing of this arrowhead was broken, as well as the shank, and the color pattern in the exposed section of the wing was similar to that I had seen in Figure 3.  See Figure 5., below.  I assumed that the wing had been broken recently, perhaps by the horse or the plow during the course of farming, while the shank had probably been broken when the piece was more or less new.  I also assumed that the artifact had been the dark brown color seen in the center of the broken wing when it was new.  It occurred to me that I could probably verify this assumption by breaking the piece, but I was horrified by the very thought because I still saw these artifacts as works of art to be taken at face value and not as items with which to play out one’s scientific curiosity.  

Figure 5.

In 1953 I was a raw graduate engineer working at my first job since college, at Bell Telephone Labs.  My assignment was to run, fetch, and carry for one Rudi Kompfner, the inventor of the Traveling Wave Tube (TWT) and the Backward Wave Oscillator (BWO).  Rudi was a very impressive person, indeed.  He once went to some effort to spell out for me the sin of “duplication of effort”, as applied to the case of government financed research.  No one wanted to spend good money to re-invent the wheel, he said.  I’d had this lecture before in college, along with the counter argument that many important discoveries had been made by revisiting old and well-established theories.  There was also the widespread doctrine that all new knowledge, no matter how seemingly irrelevant at the time, would most likely prove to be useful, if not vital, sooner or later. I was reminded of the farmer who assured me that “them University Professors had done got every one of them thunderbolts” off his farm.  I told Rudi of this incident and brought the two artifacts I had showing surface related color patterns to show him.  I also related how a professional archaeologist had once told me “there was no way to find the age of an arrowhead”.  It was my guess, however, that these color patterns somehow held that secret.  Rudi was duly impressed, but he suggested that reducing the evidence before us to a convincing evaluation of the age of the artifact was a daunting challenge, indeed.  A simple Cost To Benefits estimate was not very inspiring.  Like, Who Cares?  Even if I could see a clear path toward reducing the evidence, which I emphatically could not, I was wholly preoccupied by more pressing matters.  My supervisor was constantly on my case for results on the projects he had assigned to me and I was anxious to learn everything I could about the underlying principles of those matters.  The age of arrowheads would have to wait for yet another day.

The matter became a hot topic in my mind several years later when I was working in the vacuum tube industry at Varian Associates in Palo Alto, California.  The details are spelled out in “Finding The Age”, a memo on the Web Site referred to earlier.  The production line for a Backward Wave Oscillator (soon to be made obsolete by Solid State technology) had come to a grinding halt due to the failure of a routine machining operation and it fell my lot to get to the bottom of it.  The problem arose when the order of a brazing operation and a machining operation was reversed.  To be specific, traces of Sulfur had been alloyed into the raw metal stock with the intent of making it easier to machine, but a brazing operation in a Hydrogen atmosphere furnace facilitated the removal of the sulfur from a surface skin and a consequent hardening of the surface.  Once we found the cause of the immediate problem the fix was obvious.  We simply returned to the old way of doing things, but the revelation that Sulfur was involved created a great furor.  It is deeply embedded in vacuum tube lore that certain elements, Sulfur, Chlorine, Iodine, Zinc, etc., and etc. were devastating to cathode health and/or vacuum integrity and I was assigned to find the rate at which Sulfur could be expected to enter the vacuum from the Stainless Steel body of the BWOs.

I was overwhelmed at first, but a fellow Varian employee, one Lewis Hall, a young man with a recent PhD in Physical Chemistry, became my coworker and mentor on this project.  He derived Fick’s Laws of Diffusion for me (click on Fick’s Laws at the website referred to earlier for a complete discussion) and I noticed right away that these were identical in form to The Heat Equation.  Lew pointed out that this was because the Heat Equation describes the scattering (by diffusion) of heat energy in the form of atomic motion throughout a solid, liquid, or gas in a manner exactly analogous to the diffusion of trace atoms moving throughout a solid, liquid, or gas by a process he called “Thermally Activated Random Walk”. 

The project came down to the measurement of the diffusion parameters (the binding energy and vibration frequency) of Sulfur in solid solution in the Stainless Steel we were using.  I prepared the samples and fired them at various temperatures for various times in a Hydrogen atmosphere furnace.  I also served as the machinist for the project, carefully removing a thin skin from the surface of the various samples, before and after firing, and taking the turnings to the chemistry department for analysis.  The chemists determined the concentration of Sulfur in the chips, before and after firing, while Lew analyzed the results using Fick’s Laws.  The data matched the theory remarkably well and we were soon in possession of the diffusion parameters that proved to be independent of the temperature, as well as the Sulfur concentration, as close as we could determine. 

We were concerned at the outset that perhaps the diffusion parameters might depend significantly on the amount of Sulfur present.  Certainly the hardness and/or toughness of the steel was so dependent, as I could readily tell from the sound of the cutting operation as I removed the skin for the chemists.  But the data was clear… if there was any such effect it was very minor. 

I brought my arrowheads to Lew after this job was over and asked his opinion regarding our ability to determine the age of them in the light of what we had just done. He guessed that this would be “a piece of cake” if we had the time and the money, but he was also quick to point out some complications we might well run up against.  To begin with, he pointed out that the material we were looking at, the stone, was much more like a glass than a solid and that the external environment, like the relative humidity, could be an important factor.  For example, suppose the moisture in the air was slightly acid and altered the glassy structure of the stone near the surface.  This might have a significant effect on the color independent of the concentration of the trace atoms we presumed to be responsible for those colors.  We both knew that the color of everyday glass ware was critically dependent on the concentration and species of trace atoms dissolved within, but the details of the physics was not clear to either of us.  Since we had no way to know how the environment might have changed over the time period in question, there could be considerable uncertainty in the results if this was an important factor.  On the other hand, he said, the color patterns we were looking at were probably very complex and this could ultimately work to our advantage once we had a complete theory in hand.   Suppose, he suggested, that the color was a result of several factors such as the glassy structure, the species of trace elements, the external environment, relative humidity, temperature, acidity, etc., and etc.  It would be a major chore, to be sure, to come up with a theory for all of these factors, and their interactions with each other, but modern technology was full of such complex situations that had been fully mastered.   In a worst case scenario, Lew suggested, a complete theory could very well lead us to a very narrow range of time lapses consistent with all of the findings.  On the other hand we might also find that the physics was fairly simple, as we had found in the case of Sulfur in Stainless Steel.

Lew and I took the arrowheads and our speculations to nearby Stanford University and the Archaeology Department there.  These people were very interested and suggested that if we could come up with a scheme to routinely and reliably measure the age of stone tools that would be a very valuable breakthrough event for them, indeed.  The physics, however, was wholly outside the range of the expertise of anyone in the department and, most likely, in the whole of archaeology.   On the way back to Varian, Lew and I reckoned that there would be no enthusiasm on the part of management there for the kind of study necessary to yield results.  Certainly we were both far too busy working on vacuum tube production yield problems to get involved.  The age of arrowheads would have to wait for yet a while.

In 1961 I transferred from Pilot Production to Central Research.  CR had recently embarked on a wide-ranging program to develop and exploit certain “exotic” materials such as Yttrium-Iron-Garnet (YIG), Lanthanum Tri-Fluoride (LaF3), and all manner of Semi-Conductors.  During the course of a casual discussion with one of the people I played bridge with I learned of his project to measure the magnetic properties of YIG, which was being produced in one of the labs on site.  It struck me that there was a simpler way to go about this and, to make a long story shorter, I was invited to join CR to develop the instrument I had in mind.  This effort was successful and I soon found opportunities to work on other instruments to measure various properties of materials, some “exotic” and others not so exotic, some even mundane.   I was also given some supervisory duties over the CR Machine Shop and Electronics Shop.  These facilities built hardware and electronic equipment in support of the various research projects.  There were more or less a half dozen PhD Senior Scientists in CR with independent, but somehow related, projects underway.  Most of these had to do with Solid State Physics, Lasers, and Exotic Materials.  

One of my first “Properties Of Materials” instrumentation tasks was to measure the thermal conductivity of LaF3.   I had always been interested in Heat Transfer as one of the central problems that must be seriously addressed before any vacuum electronics device can become commercially viable.  As J. R. Pierce (a major luminary in the vacuum tube firmament) once put it, “those who solve the Wave Equation tend to get all the glory while those who solve the Heat Equation are the ones who make it all work”.   Major number crunching computer power had recently become available to us in CR in the form of FORTRAN programming as well as Tymeshare IBM 360 Basic, so I was able to perform experiments on fairly complex thermal networks and use the computer to reduce the data and come up with the desired results by implication.  In the specific case of LaF3, I constructed an instrument with two Copper blocks, one a heat source and one a heat sink.  I could measure and record, quite accurately, the temperature of each copper block and, even more accurately, the temperature difference between them.  I could then insert a sample of LaF3 of almost any simple shape between the blocks making thermal contact using a proprietary ‘thermal grease’, heat one of the blocks slightly with a small torch, and then record the cooling transient.  There were, of course, many different heat paths and at least several impediments to heat flow between the two copper blocks, in addition to the LaF3 sample, but once I had constructed a complete computer model of the whole network it was fairly simple to sort out all of the relevant parameters and arrive at a completely independent and reproducible value for the contribution of the LaF3 alone.   Before claiming victory I also used this setup to compare my results with some generally accepted values for the thermal conductivity of some common materials such as Copper, Iron, Tungsten, Sapphire, Beryllium Oxide (BeO), etc.  I was very gratified by the results.  The only material I was unable to characterize at all was Diamond.  The thermal conductivity of Diamond is very high indeed and unless a favorably shaped sample is available the true value is apt to be lost among the various inevitable uncertainties in such a measurement.

The complexity of this problem struck me as quite similar to that of a worst-case scenario in sorting out all of the important effects in determining the time involved creating the color patterns I was looking at in my arrowheads.

Instruments to measure the dielectric and/or magnetic properties of various materials were soon to follow.  The coefficient of thermal expansion was of considerable interest in some cases and a Laser Interferometer due to Sol Miller became available early in the game and proved useful to this end.

Perhaps the most useful instrument we had in CR for studying the basic structure of semiconductors and other solids was the Laue Camera.  This is a relatively simple device although a detail description of its operation is far beyond the scope of my argument here regarding the age of stone artifacts.  Abe Kaufman, who held a PhD in Solid State Physics, was its master and he rejoiced in explaining how it worked and what wonderful stuff one could learn from it.   When I was a graduate student in college I taught a course in Power Transmission and was more or less familiar with the propagation of electromagnetic waves in one and two dimensions and the nature of constructive and destructive interference as between incident and scattered waves.  In the Laue Camera we have a source of X-Rays with a wavelength on the order of 1 Angstrom (1E-10 Meters).  This wavelength is comparable to the distances between the atoms in most solids.  The X-Rays are made and confined within the source device except for a long thin hole a fraction of a millimeter in diameter.  A highly collimated X-Ray beam emerges from this hole and is directed toward a sample of the solid under study.  The atoms of the solid scatter the individual X-Rays in all directions, but if the atoms are arranged in orderly 3-dimensional arrays, as they are in most solids, the reflected X-Rays will reinforce each other in phase in certain specific directions.  In all other directions the X-Rays interfere destructively and are not detected.  A photographic film sensitive to the X-Rays is placed where it will be exposed only in an array of small spots, images of the collimating hole.  Abe was able to look at such a film, a “Laue” as he called them, and tell at a glance the crystal structure of the solid.  He explained to me that there were only a small number (14 if memory serves) of possible crystal structures with names like Cubic, Body Centered Cubic, Face Centered Cubic, Hexagonal, Spinel, etc.  (The DNA Double Helix is apparently one possibility).  By measuring the angles and distances between the spots on any given Laue plate, Abe could tell the absolute distances, in Angstroms, between the various planes in which the atoms had arranged themselves.  I gathered that a wide range of the properties of a solid could be determined from its crystal structure.

I also learned from Abe that glass did not have a crystal structure.  I was keenly interested in scientific (as opposed to artistic) glass blowing ever since my days in college and took every opportunity I could to become proficient at it.  My first mentors in glass blowing told me that glass was not a solid, but rather a very viscous liquid.  Two simple demonstrations were offered to emphasize that conclusion.  In one case a horizontal length of glass tubing about ½ inch in diameter and 4 ft long was supported at each end for several days.  It was then removed and placed on a flat surface.  When rolled along this surface it was quite apparent that the tubing had a slight, but observable, bow in it that was not apparent at the start.  Another demonstration had to do with the proper way to break glass tubing to the desired length.  A Diamond or Tungsten Carbide tool was used to scratch, or score, the tubing at the place where a break was desired.  Applying a sharp bending moment on either side of the score would, if done right, result in a clean break at the desired place.  An experienced glass blower would, without thinking about it, pass his thumb over the place where the glass was scored before applying pressure.  Failure to do this would usually result in a less than clean break.  The explanation offered to me was that the original score ruptured the bonds between the atoms of the glass to a slight, but significant, depth below the surface.  Left alone the glass would quickly heal itself, but passing the thumb over the score, particularly after the thumb had been dampened with the tongue, would allow some moisture to penetrate the rupture and prevent or deter the healing.  The deeper the rupture the weaker the bonds and the glass would break cleanly where desired.  One of my tutors had worked for years in the Neon Sign business before becoming a Master Scientific Glassblower and he told me that most “tube benders” learned this trick of the trade by osmosis, from seeing others do it, as opposed to any specific guidance.

Further evidence of the liquid nature of glass was offered to me during a recent discussion of this matter.  A tour guide had told my informant last summer while he was visiting an ancient cathedral in Europe that the Holy Figures in a stained glass window were sagging slightly, but perceptibly, due to this characteristic of glass. 

Another demonstration of the liquid nature of glass may be found in the observation that broken glass may have some very sharp edges when the break is fresh, but over time the edges become noticeably less sharp.   I am familiar with some archaeological evidence to the effect that Obsidian (a volcanic glass) knives had been used to open the skulls of some Pre-Columbian people in Latin America.  The patients (victims?) had survived, as healing of the bone was evident.  The lore included a statement to the effect that freshly broken Obsidian produced some of the sharpest edges known.   The evidence for this must be considered anecdotal In lieu of careful study, but in the early 1990s I served for a short while as a mentor to a college student working on a degree in Forensic Science.   He was interested in developing a procedure for determining how recently a piece of broken glass found at a crime scene had been broken.  The procedure we discussed was first to determine the viscosity of the glass as a function of temperature and, from this information, determine the bonding energy between the atoms making up the matrix of the glass.  We should then be able to calculate the rate at which atoms at a sharp edge would migrate, by self-diffusion, away from a sharp edge and toward the thicker parts, thus rounding and reducing the sharpness of the edge.  We proposed to measure the “sharpness” of an edge by measuring the force require to sever a standard fiber… such as a strand of spider web. 

We also discussed another property of glass that might be useful to a forensic scientist.  When light passes through glass any local stress tends to cause the plane of polarization of the light to rotate.  The angle of rotation is roughly proportional to the degree of stress.   A polariscope to observe this phenomenon is a basic instrument to be found in every laboratory where scientific glassware is made. The polariscope is a very simple device with two polarized windows on a common axis placed several inches apart.  Anyone who has ever seen a 3-d movie is familiar with the polarized glasses that are required to enjoy the full effect.  The screen is illuminated with two superimposed images.  The light is polarized so that one image is polarized 90 degrees away from the polarization of the other image.  One window of the glasses will pass light of only one polarization while the other window transmits only light polarized 90 degrees apart.  Many people, once they get home, have placed the two windows one against the other and noticed that the pair can become almost opaque when the angle between the orientations is right.  The polariscope in the glass lab works on the same principle.  An incandescent light behind the first window emits photons of every polarization.  The first window passes selectively only those photons of one polarity.  If the second window is orientated 90 degrees from the first, most of the photons will be blocked there and the view looking into the second window will be dark.  When the glass blower places his work between the windows he can readily see those regions with localized internal stress.  An annealed piece of glassware will appear dark in this case. The novice glassblower may soon notice that almost any piece of glass will cause the polarization of light passing through it to shift perceptibly due to any small pressure he may apply by hand.  The polariscope is a very sensitive instrument.

 During the course of glass blowing the heated portions are rarely allowed to cool slowly after being worked and the finished product is apt to have a lot of local stresses.  These can make the item more fragile during normal use than if the glass is free of local stress.  Thus an annealing oven is also a basic requirement in a glass lab. When the glass blower is done fashioning a piece of glassware the work is normally placed in the annealing oven.  In the case of Pyrex type glass the oven temperature is brought slowly to around 400 DgC and then allowed to cool slowly to room temperature, the entire cycle lasting perhaps 6 – 10 hours.  Most glass used to make vacuum tubes and chemical ware is worked into shape at around 800 – 1000 DgC.   At the annealing temperature the work will not sag perceptibly, but on the atomic scale each atom will find a location with respect to its neighbors where the forces of attraction and repulsion are more or less in balance and the energy stored in stress is a minimum.  When examined in a polariscope the stress free condition can be verified.

In addition to having very sharp edges, freshly broken glass has considerable localized stress on and near the fresh surfaces.  The forces on the atoms on the freshly broken surface are greatly out-of-balance as compared to the situation before the break.  This can readily be demonstrated by observing the polarization of light reflected from a freshly broken surface.  As time goes on, however, the surface atoms will migrate (by thermally activated random walk… self diffusion) into nearby positions where the total stress energy is again minimized.  The time required depends on the atom-to-atom bonding energy, the local viscosity, and the temperature.  Overnight in an annealing oven would probably do the trick, but at room temperature at a crime scene my intuition tells me that several days or weeks or perhaps months would be required before the surface stresses would be undetectable.  To my knowledge, this research never got beyond the discussion stage as the young man failed to show up for a regular appointment with me and never answered any of my subsequent calls.  

In the mid 1970s a man came to my office where I had some arrowheads on display.  He invited me to his home to see his collection, which was spectacular, indeed.  Several walls were covered with beautiful specimens numbering well over 2000 by my estimate.  Most spectacular as well were the brilliant colors and near perfect shapes.  My host was a geologist working for the US government and he had collected rocks from around the world.  His garage was full of boxes of these rocks, along with a diamond saw and other gem making tools.  He had made, as a hobby, all of the arrowheads on display, but not using the methods used by the aborigines.  He selected from a small bin several blanks cut to the rough outline of an arrowhead and then took me back to his indoor workshop where he could finish the piece while watching TV or listening to music.  The most basic tools here were several items resembling large nails, tipped by Diamond or bits of Tungsten-Carbide, as well as some rubber sole ‘footies’, such as those I had seen people wear around a swimming pool.  I was about to get my first lesson in how arrowheads might be made for sale to the tourist trade in the North Western USA.  The blank was placed on the footie, which has just the right hardness-softness to allow the removal of a single flake without excess shock to the rest of the piece.  Using a pointed carbide tipped nail, my host applied pressure to the edge of the blank and a narrow flake in length roughly the width of the blank was produced.  After a dozen or so flakes were thus made, he removed the work from the footie and dumped the flakes into a small tray.  He mentioned that these flakes were razor sharp and that he had lost well over a pint of blood while learning these techniques.   The blank had taken on the look of a real arrowhead where the flakes had been removed.  Perhaps 10 – 15 minutes from the start, my host had a finished piece that would fool almost anyone except for the fact that the edges were very sharp and all surfaces were brightly colored.   He said that professional forgers for the tourist trade had a number of ways to “age” their works.  He preferred the beauty of the raw works and did not age them, but he showed me a homemade rock tumbler he used for other purposes such as polishing gemstones.  It was a simple device using a small electric motor to drive a shaft made of concrete re-bar.  An old tire suspended on this would rotate at just the right speed for tumbling rocks in a slurry of slightly abrasive sand.   Before I left his hospitality, my host gave me a blank and the necessary facilities and I made the item shown as #3 in Figure 7., below.   The edges are still slightly sharp today in 2004.   A client, who told me that she bought them for $1 each at a roadside stand in South Dakota, gave the other items, #1 & #2 to me.

While the sharpness of the edges and the general patina on the surface of stone tools may enable us to distinguish counterfeits from the real thing, these factors are of little or no use when it comes to determining the passage of centuries.  Or such is my opinion.  Nevertheless we cannot know too much physics when it comes to sorting out all of the factors that may be at work in the formation of “weathering” rinds.  The surface chemistry, for example, is apt to be strongly dependent on the surface stress energy.  I can imagine that the external environment, the rainfall, the soil pH, decaying vegetation, etc. could alter the structure of the glassy surface considerably over the first century or two with more vigor than I would suspect after the surface stresses had annealed themselves.    

When Lewis Hall and I first considered the surface-related color patterns observable in two of my arrowheads, we had just finished a study of the diffusion of trace elements in a solid by the process of Thermally Activated Random Walk, following Fick’s Laws.  We assumed that something similar, although not necessarily an exact analog, was responsible for the color changes we were looking at in the arrowheads.  We were both aware of the glassy nature of the arrowhead material, but we guessed that diffusion in glass was probably quite similar to diffusion in solids… i.e. characterized by an activation energy and a frequency factor.   We were also quite familiar with the fact that faint traces of elements, mostly metals, were universally used to produce color in glass.  Cobalt, for example, made some glass blue, while Chromium made some glass red, and Uranium made some glass green. 

We were also familiar with fluorescence.  In RADAR school in the US Navy, I learned that oscilloscope CRTs (Cathode Ray Tubes) used various ‘phosphors’ to produce various display features.  For general use we used a CRT with a green ‘low persistence’ screen.  The screen emitted green light when a stream of electrons (a cathode ray) struck the phosphor.  The light intensity decayed very rapidly as soon as the electron beam was turned off.  The CRT used to display RADAR targets used a ‘high persistence’ phosphor screen… roughly yellow in color.  Any spot excited by the electron beam continued to give off light long after the beam was turned off.  Those screens also tended to glow in the dark long after all CRT power was turned off.  Fluorescent lights as well as an electron beam could also excite the glow.  Quite clearly, the pattern of colors in my broken arrowheads could arise from a variety of physical effects, most having to do with the properties of the material (the glass) of which the arrowhead was made as well as the species and distribution of trace elements.   A great deal of information is thus available to us if we could study the fluorescence and the persistence of any light emitted by a sample of rock found at an archaeological site when it was made a target in a cathode ray device.

I have discussed this subject with several professional archeologists over the years and I have heard the term “weathering rinds” more than once.  It is quite apparent that I am not the first person to observe these color patterns.  It is also quite apparent that they are widely believed to be due to the external environment far more than any physical effects like random walk within the artifact.  This being the case, it is easy to see why there might be a lack of enthusiasm for any serious study of the phenomenon with the goal of determining the age.  The weather, the climate, the pH of the soil in the precise locality where an artifact is found is not knowable over any extended period of time.  At least it was not knowable before serious tree ring studies have shed much light on the world’s climate over the past 7000 years.  (The microclimate of any locality is still apt to be a deep mystery).  Thus, if the observed color patterns are exclusively a result of external factors, any such study as I may propose is apt to be fruitless. 

This was made clear to me early in the game when I was introduced to the phenomenon of “Obsidian Hydration”.   Obsidian artifacts tend to exhibit “weathering rinds” under close observation.  I was once taken to a laboratory where a number of thin slices of obsidian taken from several arrowheads were being studied.  These slices were perhaps 0.25 mm thick and were quite transparent.  The laboratory was well equipped to study, in fine grain, the optical properties of these samples as a function of depth below the surface.   The technician, who seemed to be quite knowledgeable, explained to me that her technique was useful for determining only the “relative” ages of artifacts found in the same locality because of weather and other variables (like soil pH) at distant sites.  She was wholly non-receptive to the idea that trace elements moving outward by Thermally Activated Random Walk could possibly be a factor.   She was unable to give me an account of either the physics or chemistry of Obsidian Hydration and I was never able to find any such theory elsewhere.

I was exposed to several lectures on the general subject of Scientific Research during my college years.  One of my professors in graduate school went to some effort over an extended period of time to spell out his philosophy on the subject.  He drew an analogy between discovery in the laboratory and discovery over land and sea.  Before Lewis & Clark made their famous trek over the unexplored lands of the Northwest US, for example, they made a thorough study of the maps and notes of those who had gone before.  Likewise, the alert investigator in matters electronic would be well advised to study the writings of those who had been there and published before he did anything on his own.  The people paying the bills would not be pleased to learn that they were paying for re-inventing the wheel.  Duplication of effort be bad… very bad. 

When I started working for Rudi Kompfner he was intent on building an electron gun to produce a well-behaved hollow electron beam.  After he had explained the benefits of such a device and his ideas for making it a reality, he gave me a very rough sketch of what he had in mind with a few critical dimensions and assigned the task of filling in the details to me.  I was to make the parts drawings and supervise their fabrication in the machine shop and their assembly in the clean room.   After discussing the assembly details with George Helmke, the Master Tube Tech, and submitting a number of drawings to the shop, I got a copy of Pierce’s book on Electron Beams and started studying it.  Kompfner took note of this and during a coffee break we got into a general discussion of his philosophy of research.  He told me of his first day on the job after he had been hired by an architectural firm… his degree being in architecture.  His boss gave him a rough sketch of a structure and asked him to piece out the details and make working plans for its construction.  After studying this assignment he sat looking at a blank vellum on the drafting board for too long.  An old hand, sensing his dilemma, came over and suggested that he start by drawing a baseline.  This done, the rest of the design seemed to gradually fall into place more or less naturally.  “Do something”, he advised, “even if it is wrong.  The worst approach is to do nothing.”  Science, he said, is a self-correcting discipline.  Nature will give you the bad news soon enough.  Such is my experience as well.  

He then told me his version of a story I’d heard previously from others, about how he came to invent the TWT. The group he was working with was developing and building Klystrons and Magnetrons for wartime RADAR applications.  In those days Magnetrons were high power microwave vacuum tubes used mostly as RADAR transmitters while Klystrons were useful in RADAR receivers.  Both were very narrow band devices operating at a single frequency unless some facility had been incorporated to deform the vacuum envelope somehow, by way of tuning it.  This made it relatively easy for an enemy to determine the frequency at which you were operating.  He could then transmit back to you a “jamming” signal and thus defeat your RADAR.  The electronic countermeasures war was underway.  What was needed was a “frequency agile” system.  The ideal system would be capable of changing the frequency of each pulse while the receiver listening for echoes would track at that same frequency.  The enemy would require several such incoming pulses before he could determine the proper jamming frequency.  By that time, however, it would be too late.

R.K. recognized that an electronic device capable of transmitting and receiving microwave signals over a wide band of frequencies would be a very useful innovation and he began speculating to himself how such a device could be made.  The most broadband device he knew of was a 2-wire transmission line.  If he could somehow send an electron beam through the electric fields surrounding such a transmission line, then perhaps something interesting might happen.  Unfortunately electron beams were not the right shape.  Perhaps if he wrapped the 2-wire transmission line in the form of a helix and sent an electron beam down the center he might observe some useful interaction.  He ran this idea past his betters and was told that he was crazy.  These worthies had any number of reasons why such an idea was utter garbage.  But the more he thought about it the more he was convinced that something interesting … he couldn’t say precisely what… was apt to take place.  He quietly built a crude experiment using a scrap oscilloscope gun to make a very crude electron beam and he focused this beam down a crudely made helical transmission line.  He applied a small signal into one end of the helix and observed a much larger signal at the opposite end. This “amplification” was observed over a band of frequencies as wide as the range of his test equipment.  The implications were nothing short of stupendous and a new industry was born, yet it was some time before the best theoreticians were able to come up with a mathematical model to partially explain what was going on.

R.K. went to some effort to tell me that he was devoted to “Intuition” as a most powerful and vital attribute in anyone aspiring to be an innovator in any technical field. Even after the math people were able to tell him what was going on in the TWT, he was much more comfortable with his intuitive understanding of the matter.  Intuition, he said, was mostly a consequence of having worked out all of the simple problems related to a subject of interest.  The solutions to the more complex problems could not then be too far afield from this familiar territory.  I’d had a similar series of lectures from Jim Ebers, one of my thesis advisors at Ohio State.  Jim was now at Bell Labs as well and I went to visit him several times while I was working on Kompfner’s hollow beam electron gun.  Jim taught the course on Network Synthesis at OSU and he had suggested more than once in class that many, if not most, synthesis problems had no mathematical solution while intuition based on having solved all of the simple network problems was perhaps the best way to go in this field. 

In due course the Hollow Beam gun was ready for test.  I reread Pierce after this data was taken and found that his arguments meant one helluva lot more sense to me afterward than they had the first time through.  So much so that I made it a general principal, when embarking on any new investigation, to do as much as I possibly could on my own before studying the literature.  I found that the literature was a lot more meaningful and illuminating this way.  In some cases I was able to avoid serious errors that the author had made before proceeding, unaware that he was going down a dead end.  I was given another assignment before Kompfner’s Hollow Beam Gun project was abandoned.  I don’t know the details, but another scientist in the group was also working toward the same goal and may have had success first.  In any case, developments elsewhere eventually made both efforts obsolete, or so I was told later.  Such is the nature of R&D.

The matter of sorting out all of the complex physics that might be going on in weathering rinds may be as complex as any problem in vacuum electronics, but my intuition tells me that it ain’t so.  So, what would I tell some filthy rich patron who had nothing better to do with his money than to fund scholarships for a bevy of graduate students intent on earning the PhD in Material Science to get to the bottom of the matter?

To start with, I would want a well-equipped Materials Laboratory staffed by a team of experts like those I worked with in Central Research in the 1960s.  This would include the following people, or their like numbers, to serve as mentors to the grad students:

1)     Abe Kauffman, expert in Laue X-ray analysis and crystal structures.

2)     Bob Fairman, chemist supreme.

3)     Dewey Atchley, generalist with common sense and wide experience in solid state and atomic physics.

4)     Marcel Muller and Arden Sher, experts in Quantum Mechanics, Fluorescence, and spectroscopy.

5)     John Helmer, Auger Spectroscopy.

The grad students would, of course, do all of the tedious legwork.  There is no cheaper source of labor than Graduate Students.

For starters I would need a supply of raw material samples of the kind my arrowheads are made of.  The arrowheads themselves would not do, because I still see them as works of art and I would need to know precisely what I was looking for before I could bring myself to perform any experiment that might deface them in any substantial way. After I retired from the vacuum electronics industry at the end of 1996 I made a pilgrimage to Florida to visit relatives and old friends and the old haunts where Snubby and Billy and I used to find arrowheads.  Lawns and housing covered many of the sites while others were posted with warnings of the danger of herds of wild bison.  I learned from the locals that the bison are wholly non-existent, although flocks of wild turkeys and armadillos, unknown before 1950, are quite common now.  On or near Jackson’s Farm, at the East edge of Payne’s Prairie, I found several collectable artifacts along with numerous fragments that were, most likely, debris left over from tool making.  There is no other way I can imagine to account for the abundance of such material at this place. Limestone quarries and sinkholes where one can find Chert nodules weighing some 50 - 100 pounds, more or less, are common in the area and such objects are often found where the aborigines probably left them as raw stock for making stone tools. 

Figure 6.

Figure 6. shows a broken section of a typical sample of the Chert fragments to be found wherever arrowheads are found around Gainesville.  This one is from Jackson’s Farm.  It is roughly 1-1/2 inches across and shown roughly full size in this cross section.  The “weathering rind” is clearly evident.   Almost every other fragment found at this site shows something similar when broken.  These pieces have no artistic value to me and are thus ideal samples from which to start taking data.  For a start, I would probably prepare a few thin slices through the cross section shown as well as a number of cubes roughly 1 millimeter per side from throughout the sample, being careful to keep a record of where, with respect to the surfaces, each sample came from.

[Close examination of the rinds in Figure 6. shows that they are not the same thickness on both sides.  This may or may not be consistent with the weather or climate theory.  It is quite conceivable and perhaps likely that one side would be exposed directly to the sun while the opposite side would be in contact with the cool earth for long periods of time.  Just how this would affect the weathering rinds, assuming whatever scenario, would need to be taken into account and just how this factor might play out is not obvious to me at this time.]

“What kind of data should we take?” one may ask.  My intuition tells me that the central regions of the sample shown in Figure 6 are similar, if not identical, to the bulk of the Chert nodule from which is was taken.   By some accounts from people bent on making and using stone tools the way they imagine that the early people did, a wide variety of fragments, as to sizes and shapes, result when a large nodule is properly struck by a heavy cobble or hammer stone.  Many of the fragments have razor sharp edges and some are useful, as is, for some tasks around the campfire without further work.  Film footage of archaeologists and their students butchering large and small animals with such fragments have been shown on TV.  In some cases these people go on to demonstrate how arrowheads and other tools can be made from the various fragments using small cobbles, bone, or antlers to apply blows or pressure to remove flakes.  Some hobbyists have become sufficiently skilled in the “flint knapping” arts to command premium prices from collectors for their work. In one account someone gave me, an artifact forger made a fluted “Folsom” Point for a collector with some credentials as an expert who paid him $10,000 more or less.  But I digress.

Chert nodules, I am told, are formed on the ocean bottom in deep deposits of limestone… an aggregate of the shells of clams, oysters, and other shellfish.  The varieties of such formations are almost endless, as I have gathered by talking to several “Gemologists”.  Chert, Flint, Agate, Jade, Jasper, etc. and a wide variety of other terms may be heard when experts talk about the raw materials from which arrowheads are commonly made.  The distinctions may, or may not, be subtle.  In any event, these glassy formations suitable for making stone tools tend to accumulate small traces of the various elements, metals mostly, whose salts are often found in seawater.  Magnesium, Potassium, Bromine, Iodine, Boron, Iron, Aluminum… perhaps the entire Periodic Table of elements… are often mentioned as trace elements to be found in sea water as well as in Chert, Flint, etc.  Obsidian is also a very important raw material useful for making stone tools. This glassy substance is of volcanic origin and may have trace elements other than the ones commonly found in Chert, etc.

The glassy matrix can, most likely, be characterized as to its atomic structure and chemical composition into one or another familiar Gemstone types.  Abe K. could probably tell which just by looking.  The refractive index, viscosity, thermal conductivity, dielectric constant and loss tangent, thermal expansion coefficient, etc., as well as some other basic properties could, perhaps, be found in published tables of such.  The next step, after characterizing the samples, is to study how these parameters vary with time and temperature, as well as various external environments.  Recall that Lew Hall and I determined the binding energy and vibration frequency of Sulfur in Stainless Steel by taking thin samples from the surface of larger pieces before and after they had been fired in a Hydrogen furnace at various temperatures for various times, and finding the amount of Sulfur lost in each case by chemical analysis of the shavings.  In the case of millimeter cubes of stone, perhaps some optical means could be devised to measure the loss of trace elements as a result of heating.  In the case of thin sections perhaps the transparency with respect to displacement from the surface could be measured as a function of temperature if we have a large enough sample to begin with.  The sample needs to be large enough to minimize surface effects during firing. 

Perhaps 30 years ago I saw a TV presentation on PBS regarding the work of an archaeologist studying Stone Age trade routes in Europe.  He was compiling a “Flint” database…  my characterization.  I gathered that all “knappable” rock formations useful for tool making could be, in his mind at least, classified as “Flint”.  He had made some effort to take “fingerprints” of various Flints in terms of their colors as determined by the relative abundance of the trace elements trapped within.  Using his intuition based on experience, he strongly suspected that a certain tool found in one location was made of a Flint from a certain quarry familiar to him some distance away.  A comparison of the color and trace element distribution as between the artifact and the rocks from the quarry made for a compelling case in support of his intuition.  His thesis, as I understood it, was that high quality Flint was traded all across Europe by stone age people and that it should be possible to take trace element fingerprints of at least the major known quarries and match them with the trace element fingerprints of tools found elsewhere and eventually map out some trade routes.  A comment toward the end of this presentation caught my attention.  He said that the trace element fingerprint taken from the center of a tool was apt to differ from the same fingerprint taken near the surface of the tool.  This effect should be taken into account when someone was trying to compare fingerprints with the database he was hoping to develop.  I made some telephone calls to get an address for the people who had produced the video and wrote to them suggesting that further study of the trace element distribution with respect to the surface of a tool could, most likely, lead them to the age of the artifact.  I never got a reply.  Nor have I ever heard of any follow up with regard to the trace element database.

I was particularly encouraged while watching this footage to learn that someone had gone to so much trouble to try and understand such matters.  In particular I was encouraged to learn that there are people, other than myself, who love to solve tough problems.  Truth be known, I am far less interested in the actual age of these artifacts than I am in the general problem of a fundamental understanding of what is going on with respect to these “weathering rinds”.  I am, of course, very interested to know the history of my species, but the more general matter of problem solving for its own sake is my underlying passion. My intuition still tells me that Thermally Activated Random Walk with respect to the trace atoms that give rise to color will prove most fruitful.  My intuition also tells me that degradation at the surface by external factors will probably have an effect on the diffusion rates near the surface, but there should be plenty of information further toward the interior of the artifact.  And if it turns out that external factor are important then my intuition tells me that that there are probably enough variables to lock down an elapse of time consistent with all observations there as well.

The item shown in Figure 8., below, was found at the same site as the specimen shown in Figure 6.  I see no evidence of “weathering rinds” in this piece.  What I see here is pure diffusion from a steady source of “red stuff” on one face to the other 2 faces where escape to the external environment takes place.  I have found a number of rocks with similar “veins”.  I once asked a geologist how such formations came to be and his answer made good sense to me.  As I understood him, many sedimentary aggregates tend to fracture when they are still soft and foreign material moves in to fill the gap.  Then as the sediment hardens and becomes rock hard, the material in these veins is trapped.  When broken by a blow from a cobble, the break often follows one side or another of the vein.  In this case it seems to me that the piece was broken so that the vein stuck to the piece shown here and serves to keep the concentration of the “red stuff” more or less constant at the face to which it is attached.  If this scenario is responsible for what we see here it should be relatively easy to determine how long the color pattern we see has been in formation… once we measure the heat of diffusion of whatever the “red stuff” in the glassy matrix is.  This parameter should not be too difficult to measure as there is enough raw stock here to make a number of test samples for treatment at elevated temperatures to accelerate the processes.  

Figure 8.

The matter of escape from the surface by a trace atom reaching it deserves some mention here.  In the case of Hydrogen and Nitrogen, H2 and N2, in solution in metals we find Seifert’s Law to hold true.  Seifert’s Law holds that the solubility of diatomic gases in metals is proportional to the Square Root of the pressure in the gaseous phase.  This is true because only atoms penetrate the bulk of a metal and equilibrium at the surface comes about when the diatomic gas molecules are disassociated at the surface to allow the individual atoms to find a place for themselves in the metal lattice below the surface.  An atom of H1 or N1 diffusing to the surface must pair up with another atom on the surface before recombination and desorption as a molecule into the gas phase can occur.  The bonding energy between an atom of these gases and the metal surface is so high that re-entry into the gaseous phase can happen only when 2 atoms come together at the surface.  Even so, the statistics of random walk to the surface are far more torturous than the statistics of pairing up and evolving as a molecule.  In the case of metallic atoms diffusing through the glassy matrix of a stone tool, I would be very surprised if surface effects turned out to be important in any way, but I would readily yield to any evidence to the contrary.

I was a graduate student in 1950 working under an assistantship in the Vacuum Tube Laboratory at Ohio State University.  My immediate supervisor was Prof. E. M. Boone who assigned me to serve as run-fetch-and-carry for Dr. Oscar Heil.  Heil was a very colorful luminary in the vacuum electronics firmament and, had Germany won WWII, he would have been credited with all manner of inventions, including the klystron.  One day I called his attention to a faint glow in a small glass vacuum tube… soon to become obsolete.  This brought forth an extended lecture on the permeability of glass to Noble Gasses and assorted subjects, not necessarily related.  The earth’s atmosphere, I learned, was roughly 1% Argon… a Noble Gas… the product of the radioactive decay of an isotope of Potassium.  If we assumed that the Earth had no Argon in its atmosphere in the beginning, the time required to accumulate the level we see today from the radioactive decay of Potassium would be roughly 4 Billion Years.  This result was, by no means, universally accepted among top scientists interested in such matters.   There were also traces of Helium, Neon, Xenon, and Radon… and perhaps other Noble Gases… in the atmosphere due to similar radioactive decay processes.  Alert observers in Germany had also noticed the same faint glow in operating glass vacuum tubes and had studied the matter at great length a number of years ago.   The method was simplicity itself.  An image of the glowing region was focused onto the input slit of an optical monochromator… a spectrum analyzer… and the spectrum of the emitted light was recorded.  This technique resulted in a wholly incontrovertible determination of the gas species involved.  These, according to Heil, were all Noble Gases.  No Oxygen, no Nitrogen, no Hydrogen, none of the gases one would expect to see if the vacuum envelope simply had a leak in it.  The only way these gases could get inside the vacuum was by permeation directly through the glass. 

Heil went on to tell me about a paper he had once read of a formal investigation of the matter.  A commercial vacuum tube was not a convenient vehicle for this study, so a thin wall glass enclosure was constructed with an electron gun included so that the light of recombination of any ions formed within a thin electron beam would be efficiently focused onto the slit of a monochromator.   The investigator could control the species and pressure of the gas around the outside surface of the device.  I never saw this paper, in German, but according to Heil everything that could be known regarding the permeation of Noble Gases through glass was known.  

In 1970 I was assigned to investigate the problem of small klystrons being returned from our customers due to excess gas levels.  My studies completely turned everything I had been told about Residual Gas on its head, as I have written in the report on the following website:      http://www.smecc.org/r__m__r__residual_gases.htm  .

My intuition tells me that newly broken surfaces on flaked stone tools are sites of considerable stress at the atomic level and extraordinarily active chemically as a consequence… at least until those stresses are relieved by self-annealing or otherwise. Perhaps Noble Gases from the atmosphere will be absorbed preferentially during this period.  Perhaps not.  In any case it is well known that fully annealed glass will absorb measurable quantities of Noble Gases from the atmosphere and that these gases can find their way through a glass wall on the order of 1 millimeter thick, at room temperature, over a period of days, months, or years.   Anyone seriously investigating the age of flaked stone tools through studying surface phenomena would be well advised to consider this matter.    June 19, 2004     RENE ROGERS