Video
Metal Detecting- Recent Advances in Methods and Equipment
Transcript
Karen: Okay. Good afternoon and welcome to the NPS Archeology Program speaker series for 2013-2014. My name is Karen Mudar and I am a senior archeologist in the Washington office. This fall and winter we're looking at Geophysical Technologies in Archeology. We've invited people to talk about LiDAR Geophysical Prospecting, Underwater Locational Technologies, Satellite Imagery, GIS, Metal Detecting and more. It's a great slate of speakers and I hope that you can make time for them.
I also want to welcome people back after the government shutdown. I hope that everyone is getting back into their regular routines after being furloughed. Because of the shutdown we were not able to hold the webinar scheduled for October 10th. This webinar was Heritage Preservation and 3D Immersive Learning Using Terrestrial Laser Scanning and Combined Spatial Imaging and Visualization Tools, which is a rather long title. The presentation will be given by Lorie Collins and Travis Doering who are co-directors of the Alliance for Integrated Spatial Technologies at the University of South Florida. I know that a lot of people will be interested in the presentation and I've been working with Lorie and Travis to reschedule it. Before I go on, can I ask everybody who has not muted their phone yet to do so? Thanks.
Our first speaker in this series, Dr. Fred Limp did a wonderful job of setting the stage for more detailed discussions about geophysical technologies. He provided a historical overview and examined ways that these technologies are integrated. If you missed this webinar, a video of the presentation will be posted on the Archeology Program Website. In two weeks, Ken Kvamme will talk to us about the four principle geophysical prospecting methods that are used in archeology. These are magnetometry, electrical resistivity, electromagnetic induction, and ground penetrating radar. When integrated through GIS, use of multiple methods such as these offer an increasing comprehensive view of varied archeological deposits. I know this will be a really interesting talk for us. Kvamme is the director of the Archeo-Imaging Laboratory at the University of Arkansas. Please note that this webinar will be held on Wednesday, November 6th, and not on our customary Thursday.
Before I introduce our speaker for today, I have some administration to take care of for people who are new to the webinar series. Please note that all of the lectures will be recorded and be mindful of that when you are asking questions. Set your phone to mute. Remember, though, to un-mute your phone when you want to ask a question and Doug has asked me to tell you that you can break in at any time to ask questions. This actually works best when you have a question about an image because this particular system is kind of slow when moving forward and backwards through the Power Point presentation. The recorded webcast will be posted on the Archeology Program website and I will make an announcement in the E-Gram when they are posted. If you heard about today's presentation indirectly and would like to get invitations or announcements, contact me and I'll add you to the mailing list. Also, if you do not receive the E-Gram and would like to let me know and I will add your name to that list as well.
Our speaker today, Douglas D. Scott, retired in 2006 from the National Park Service after more than 30 years with the Department of the Interior. His last position was as Great Plains Team Leader, Park Programs, the NPS Midwest Archeological Center in Lincoln, Nebraska. Doug specializes in 19th century military sites archeology and forensic archeology. He is particularly noted for his expertise in battlefield archeology and firearms identification, having worked more than 40 battlefield sites including Palo Alto, Sand Creek, Big Hole, Bear Paw, Wilson's Creek, Pea Ridge, Centralia, and Santiago De Cuba. He was awarded the Department of the Interior Distinguished Service Award in 2002 for his innovative research in battlefield archeology that started with his work at the Little Bighorn Battlefield National Monument. Doug has also been involved with human rights and forensics investigations since the early 1990s. He has worked with the United Nations and various human rights organizations in El Salvador, Croatia, Rwanda, Cypress, Iraq and has done an animal welfare case in Canada.
Today Doug is going to speak to us about metal detecting in archeology and he has long experience with this, much of it in the National Park Service. The Park Service history has a close association with metal detecting. Metal detectors are simple, effective and relatively inexpensive remote sensing tools with real value to archeologists. His webinar will provide archeologist with an overview of the physical principles that govern metal detecting and describe their capabilities and their limitations. Examples of the use of detectors and inventory, testing, and excavation will be discussed. The webinar will focus on recent developments in metal detector technology and archeological field applications of VO AP and terrestrial pulse induction machines. I've been looking forward to this webinar and I know you are too. Welcome back to the Park Service, Doug and thanks for talking with us today.
Doug: Thank you all for joining, and thank you Karen, that was a great introduction. We'll see if I can live up to it. The title that you see on the screen is not quite the same as I chose for the title of the webinar. It – They relate and what I want to point out is that metal detectors are light-weight, hand-held, near-surface, in-phase, electrical conductivity meters. They are geo-physical instruments. There is a relationship here. Of course, now it is not advancing ...
Karen: It will work, it may take a few seconds.
Doug: Well, let me just start out.
Karen: I'll start it from this end, how's that. Does that work?
Doug: There we go, it's moving. Let me point out that I've run the gambit of talking to folks about metal detectors both positively and negatively over the last 30 odd years. What people don't largely know, archeologists, we as a profession have used metal detectors since the 1950s. Quite a few of the people using them in the 1950s, including a number of very prominent archeologists, didn't talk about it because it was a bad thing or they thought they would be castigated by their peers and some were, as a matter of fact. But, it's not a new tool and I've run into a couple of cases of background.
I was talking to somebody at SAA one time and the individual said, "Well, how can you possibly use metal detectors, they are the devil's tool?" Obviously, meaning in terms of people who loot sites and they do, with those tools. My response was, "Well, do you use a shovel?" He said, "Yes," and I said, "Well, looters use shovels, does that mean we shouldn't use that tool?" I think the point was made. I've also heard comments like, "Well, all you can find is metal." Well, duh! Yes! That is what they are designed for. It's not any different from going out and finding a lithic scatter and only finding rocks that might have been lithic debitage that might tell you something about what's happening on that site and there may be varying components that you have to do in a traditional manner.
This is just a tool and I want to emphasize that all the way through this. I want to give you a little bit of history. Metal detectors are not new. They were not a result of WWII mine detecting technology. They were developed in 1881. You may be surprised to learn that the individual who invented the metal detector was, in fact, Alexander Graham Bell. The guy that made that telephone possible. He, in the process of working with telephones realized he had a tool that he didn't quite understand and it was induction. Electrical induction. It was an important part of the telephone. Then he realized you could do something else with it and developed this thing and his idea was to use it for medical purposes to be run over wounded people to find metal fragments, particularly bullets that might be embedded in bodies. He thought of it first as a medical instrument. He applied that when President Garfield was shot by an assassin in the early 1880s and in that process he was brought in to use his induction machine to find the bullet in Garfield's body.
As Vergil Noble knows if he happens to be listening, that it didn't work very well. There are a couple reasons for it. First of all, the surgeons that had been working on Garfield had been using their fingers to probe around in there and may have caused a wee bit of infection that eventually killed him. Bell got sorts of little clicks when he ran his induction machine over Garfield's body, placing one antenna underneath the bed he was laying on and passing over the body. Little did Bell know that Garfield had a new invention that he had recently purchased to sleep on and that was an innerspring mattress, so he got all of the metal and could not find the bullet. Tried a couple of times, it just didn't work out, unfortunately. He almost gave up on it at that point. By the way, there's Garfield vertebrae with the bullet hole in it that is on display at the National Museum of Medicine and Health in D.C.
Karen: Doug, can I break in for just a minute?
Doug: Surely.
Karen: Can a person who is typing on their computer, please mute their phone? Thank you.
Doug: Metal detectors began a slow development through the 19th century. Various kinds were actually developed based on Bell's principles and they were used largely for finding ore bodies in the earth, as you see there. They all built for salvage, sunken vessels and treasure, of course. They were around and have been around for a long time. Of course, the modern underwater metal detector was a pulse-induction system shown there as well, just for juxtaposition. There is a long history of these detectors being around. The person in 1927 who really set off the metal detector as a modern invention, if you will, was Gerhard Fischer of Fisher Labs, now in California as part of Technetics. He invented the serious first metal detector. There had been attempts to use in World War I as a mine-countermine device and it didn't- it was not particularly effective because the technology hadn't come along but it was Fischer who took it to the next step and it is considered the father of modern metal detectors.
Metal detecting really came into its own during the second World War, there's some British mine- anti-mine detectors and an American World War II mine detecting unit and then a modern one. There are many, many different types of models and brands out there today that are very effective at finding mines, in particularly and extensively within Iraq and Afghanistan today, and are the basis of new developments in the hobbyist and professional metal detectors in archeology.
I had to throw this one in, I apologize. This is the early two-box system in which we still use one today as developed by Fischer, it was the only one I could find a picture of from an old ad from a treasure hunting magazine back in the 50s. Again, you can see how far they have come, in principle. We'll get to the uses and advantages here and I'll also give you a few case examples. Again, as Karen said, feel free to break in if you have a specific question or public matter here.
Metal detectors are going to detect the presence of in - point: operative word of “near-surface” buried metal objects. That is a relative term. We'll come back to that talking about certain other detectors later. They are very easy to use and there is very short learning curve. Basically, a novice can learn to use a metal detector, how to turn it on, how to listen to tones in probably an hour or two. To become proficient in their use, is another matter. That takes probably 100 hours of operation to get competent in that but you can learn to use them fairly quickly. It depends on what you have to do with them. The measurements are rapidly acquired, they are continuous measurements, in other words, you are constantly getting feedback from whether or not you hear a tone or see something on a screen.
They have excellent definition. You can pinpoint very shallow targets very precisely, largely the most VLF, very low frequency metal detectors will have a range around 30 cm, some will go deeper, significantly deeper but those tend to be the most expensive and hardest to learn to operate. The average ones are usually around 30 cm and they really can pinpoint and identify targets. Particularly modern and current models of metal detectors are very good at telling you at least what type of metal you are likely to encounter.
The basic components of detector are very very simple. You’ve got a control box seen in the center of this image. It happens to be a - I want to mention, there are a bunch of different brands today, I'm not endorsing any of them, I don't get paid by anybody to do this. These are brands that I have used or tested for various metal detecting companies so I use them as examples. There are many brands out there and they are very good. The control box is the electronics that send and receive signals. You have the wand or shaft that supports the operator’s arm and also the antenna and then the coil or antenna which has a receive unit in it. You have an antenna cable that is either internal to the wand or in this case, wound around the outside of that particular shaft and connects up into the control box.
Our general rule of thumb on cost is it's about $100 per inch. You can go buy at one of the sporting goods stores, $100 to $150, $200 machine if all you are looking for is the first inch or so of soil, that's fine. If you want anything more than that, if you want to reach deeper and get better definition on your targets you are going to have to pay more money for them. They run up to about $2-$3,000 for a high end VLF machine that works on multiple frequencies, very low frequency machine or you can go to the pulse induction and they run anywhere from $3-$5,000. Pulse induction does not discriminate currently but will go as deep as 3 feet or a meter and find something as small as a sewing pin or needle. The VLFs are the ones that we use and they come in single frequency or multiple frequency sometimes 3, sometimes up to 23. The multiple frequencies are slightly better in that they give you many, many more continuous readings and cover the full range of metal buried in the surface.
Here's an image with just a few different types of metal detectors including the yellow one on the left, which is a Schonstedt, which people still use for a lot of basic stuff in finding very deeply buried cables and pipes and that sort of thing that are metal. These are just a variety of brands and types as well as a couple of small ones on the right which are hand-held probes, with your larger coils you can't find stuff in the ground once you start digging quite as easily. The hand-held probes only work for about an inch around their end, the terminal end of their receiver, but you can find things very nicely with minimizing earth disturbance that you are dealing with.
A lot of different kinds of displays and these have changed quite a little bit in the last 2 or 3 years from just a tonal, all of them have an audio output of some sort that changes tone with the type of metal. They are not consistent among brands but within a given brand they are, generally speaking. They also have a digital read-out of various types. The one that is in the lower right there is a Minelab Quattro Pro, it gives you a read-out as just one example of the many types that are available. Newer ones out have colored screens on them and I'll show you an example of that in a little bit. The largest advance in metal detecting in the last 10 years has been one in coil technology - the antennas. And you can see all sorts of different ones here in all sorts of different sizes, open loops to close loops, open elliptical versus circular and so on.
It really depends on the job. Just like a ground penetrating radar uses different antennas, same thing with the metal detector. Any near surface stuff, anywhere from an 8-11 inch coil is usually good and whether it is elliptical or circular really doesn't matter. The elliptical ones allow a little bit better manipulation in rocky or brushy terrain because you can get in places you can't with a large coil. Just something to keep in mind when you are looking at it.
Here's an ideal place to go metal detecting, broad open area, scenic. This has to be at Little Bighorn. That's Charlie Hacker from Santa Fe, Barry Ludwig from Fort Bowie, Park Service, and on the right is Chris Adams with the U.S. Forest Service in Truth or Consequences, New Mexico. Probably 3 of the best metal detectorists I've ever run into.
We can also work in a variety of environments. This is at Sitka, Alaska. You can work with metal detectors when it is wet, which we did, helping Bill Hunt look for the Tlinget Fort that was shelled by the - or bombarded by - the Russians in 1805. We found the stuff, too We had to wrap our detector coil or control boxes in plastic to protect them. Newer detectors have full waterproof control boxes. Some do, some don't, if that is what you need, a wet environment. Some are totally submersible, some of the VLF machines are totally submersible now. Others, you can't get them wet. By the way, you don't want to use them where you have a lot of lighting because they will act like a lightning rod.
The methods - how do you go out and do an inventory using a metal detector? It is exactly the same as you would in any other kind of situation. This is a tool. How you use it to sample a site and what you are doing, is like what you are doing in any survey, walking transects of whatever it might be. Your imagination will make it work. What is your goal? The closer you space a metal detector in walking a transect the better recovery you are going to get for information as it would be in a visual inventory. You can do radial, that has been very effective in certain kinds of sites to determine boundaries, you can do it linear. When the VLF machines were single frequency, people largely advocated doing a perpendicular, doing one set of transects one way and then using another VLF machine on a different frequency in 90 degrees to that. That's a great technique. Today, with the multi-frequency machines you don't need to do that but again, the method you use is, you are going to get information. The wider your transects, the less information you will receive.
If you are looking for boundaries of sites or even just trying to find a site, a 10 meter wide transect might work. Something else, you might want to go shoulder to shoulder. It is just like any other inventory technique. How much information do you need and how you are going to apply it - which is the best. There is no right answer to that. It is a project specific situation and the date you need to acquire. This is an example of some volunteers who are learning to use metal detectors in the Southwest. This is Charles Hacker, again, from Santa Fe, working with some Native Americans and other folks and showing them how to use detectors and, again, fairly easy to learn and get a handle on them. Proficiency comes with experience.
The critical element of using a metal detector: think of this as sampling. The better you sample a universe, the more information you are going to have that will be useful. Actually using a detector in a sweep, no matter what kind of transect you might be using, this zig-zag pattern which is incorrect there on the left will work but you will miss a lot of data. It is a pretty gross sampling thing. If you are in a hurry it might be okay to use but generally not. If you use the correct one, which is also easier on your shoulder, on your elbow and your hips in walking a transect is using a nice little narrow u-shape pattern overlapping sweeps. One, you get better information, two, ergonomically it is much better for you. In setting that detector so that when you use it the length of the wand is so that you can stand upright and really be a bipedal kind of person is really important, so hunching over is not the best thing for you. You get pretty tired pretty quick. That is more critical than how you do your transects. Using that detector properly in that overlapping u-shape sweep is the best technique that is out there at the present time.
Now, here is an example of a new, just issued in the last 18 months, Minelab, and I'm not advocating Minelabs because there are lots of other good detectors out there but I just wanted to show you an example of one of the newer machines and it has a lot of bells and whistles on it. This also costs $2,500. Colored screen, it has a GPS built into it, hiking grade, it has a number of capabilities. It shows you the direction you are walking, you see the grid system there on the left image of the actual control box console and lots of buttons to push. That grid can be as small as 10 meters or as large as a couple of hundred meters depending on what you want to do. Displayed on that are a series of yellow and brown digital signals. It is reflecting a metal target and it is constantly sampling that and giving you the hardest return. The location on the screen-there are also digital read outs and audio signals that you can pick up that will tell you roughly the type of metal it is.
In that case we are looking at aluminum or possibly brass. Again, it has some other information on it. You can switch this to a mode to record your transects or your manner of walking area and you can record with this one your find objects. It is very simple GPS and GIS unit. The right element on the screen you see shows the transects and the finds along the transects. It shows my, let me get the pointer up here. It shows my starting point, back and forth, zig-zagged, or looped back and forth and ended up here at the checkered flag. I won the race. These 4 items there are targets that I recorded as I found them. This is a proprietary software called Exchange 2 from Minelab and let me show you the next image here. This is the screen that you do in editing on the computer. In this particular case it is a brass Gallagher civil war cartridge case. It gives me my latitude and longitude. That is the only option you have, unfortunately. I can put a description in, I was able to tag an image to it, I can put some more information.
One of the most important things for me is down here under Target, it records its conductivity ranges. Each manufacturer decides what their own conductivity range is but it's ferrous content, 14 and high conductivity range is 25, which would indicate brass and it gives me a depth of the find at 15 cm, which it was not found at 15 cm, it was found at about 5. Depth in metal detecting read-outs are only approximations, they are based on certain principles that don't always apply to what we do. It tells me the mode I’m in, which I created a customized discriminate, a minimum discrimination mode so I am not discriminating out any metals. Sometimes you can set them to discriminate out iron or aluminum, but you also lose other things when you do that. We are dealing with in metal detectors, the electrical conductivity properties of the metal itself. Aluminum and brass conduct similarly which is why they show up in wiring in homes. That's just the case. There's a little bit more detail here in this image that is captured. This program links to Google Earth.
A lot of good points to this, the negative is that in this particular version of the software, I cannot link this, I cannot upload this to Excel or a shape file. I have to hand enter it and work with it that way. I can't transfer this at this point because it is proprietary software. I think the next version they will be changing that. As for law enforcement work where they need to have it into a database and in - particularly in our field - in archeology, you can't do that and I think they will change that and make it more desirable for archeologists. Let me give you a few case examples and in the process I will be talking more about capabilities and equipment types and what is being done.
This is a site in Germany that was found by metal detecting and it is kind of an important one. It is where Varus's legions were destroyed by Hermann in 9 A.D. This is one of the oldest sites I know of actually found by a metal detector. It was an amateur, working within the constraints of the requirements of the German government who had to report all of his finds. When the archeologists looked at his finds, he had a working hypothesis that the Kalkriese site where Varus's legion was destroyed was in this area and he did find evidence of it and this is one of the things he found with the metal detector. He was pretty excited and it was an important find but all of this came together with him as a Major in the British Army, retired, and I believe he is deceased now.
He did a great job in working with a professional archeologist and when the professionals came in they continued to use him to help them identify areas of the site that were then tested by traditional means and as a result the professionals were able to find the wall where - that had been built up by Hermann and his German troops and to catch Varus's legions in a real narrow, in what today is a nice wide large valley but then was a narrow strip of land through a swamp and caused the destruction of the legions or at least the last component of those legions.
They can be used, they are being used on classical antiquity sites a lot today. Part of it is to find and guide archeologist to deposits where they will gain the most information, not just to look for coins and stuff but actually find metal-bearing areas that will give us something about manufacturing or living areas or whatever, so lots of functions for that.
Here's another example I did a few years ago, which is the Black Jack site, in Kansas. This is where Henry Pate and John Brown met in the first pitched engagement of the pro-slavery, anti-slavery small war, if you will, the border wars in Kansas about the free-state versus slave-state stuff. This is on the Santa Fe Trail, that's - the yellow area are the ruts of the Santa Fe Trail - and our job was to find the location of this pitched engagement, which was located down in here. We know that Pate's wagons were parked up on this Santa Fe Trail area. We used volunteer metal detectors and worked the area. While we did find evidence of the fighting represented by the bullets, and what’s one interesting thing about this – as an aside - is that Pate's Missourians were armed with the latest rifle muskets, this is 1856, issued probably from the state arsenals. This may have had an overtone about who [inaudible 00:34:52]. These are all wagon parts on the left. These would be from the Santa Fe Trail, and not necessarily from Henry Pate's staying there but just wagon parts and harness that was lost on the Santa Fe Trail.
In addition, we found a large amount of metal material in a cluster along with some ceramics that were lying on the surface or came out in excavation holes with the metal targets. That turned out to be the residual cache of materials that had been left behind by people on the Santa Fe Trail. This is not far from their starting point in Westport, Missouri and as they moved across Kansas whether it was the Overland trail up north, the Mormon Trail, or the Oregon-California Trail or the Smokey Hill Trail or the Southern Trail, it doesn't matter. People dropped things and discarded them and cached them, mainly, perhaps, for other people to use. The classic is, get rid of that piano, we aren't hauling that thing west. Those kinds of things we found in caches. We actually had important trail debris and we could see where camping sites were occurring. This was near water -, surprise, surprise - but that information was out there. Not only did people lose things from their wagons and their harness, but they also either lost or disposed of things along the trail and we can pick those things up. Metal detecting is a very, very effective way to do that.
Just with this John Brown site at Black Jack, we created view sheds using GIS based on the distribution of those combat-related items - bullets - to see who had the best view-sheds, and we can determine that and so it is an application of what the military would call a “terrain analysis” or “fields of fire.” “Weapons stand analysis” is another term. Henry Pate down here, I'm sorry, this is what Brown could see as opposed from what different places within these environments, so he had a good field of fire is what it turned out to be. That is the kind of, take it beyond the artifact and distribution of artifact and turn it in to the understanding of actual combat functions there.
Here's a case at Wilson's Creek Battlefield. Found an area there by metal detecting that was obviously a large trash dump. This area here, we then said, "Well, this is not what we want to doas professional archeologists, get in that trash dump. We need to bring other geophysics in to see what we have got here." The trash dump was there, we suspected it might be near a house, a cabin, that happened to have been occupied by General Price, as his headquarters was a farmstead of a guy named Edwards and lo and behold, geophysics did turn up a little bit of evidence of a structure of some sort in here which has been later to be interpreted as the Edwards Cabin location. General Price's headquarters was important for Wilson's Creek, but more importantly we were able to find a farmstead home-site based on the distribution of trash. By the way, there was nothing at all on the surface in that location other than a little rise. I suspected that might mean something based on other experience in the world for a long time .
This is another site type. This is an Apache wickiup in the Southwest, courtesy of Charlie Hacker. We all know this must be pro-historic because there is nothing laying on the surface around here, maybe a few lithics, but when they metal detected this, low and behold it became 1850 or later. These are cartridge and cartridge cases, tinklers, beads, a bracelet, and bullets here, obviously projectile points and a knife gun part here. You don't always want to assume what you see on the surface that something isn't represented below it that might help date it diagnostically because there was no metal at all on the surface of this site.
Here's one in Western Colorado. This is a wickiup, a brush structure on the Uncompahgre Plateau, it was done by Curtis Martin of Dominguez Archeological Research Group, here in Grand Junction, Colorado. This is another one there with no surface evidence of the dating of this site. Dendrochronology is being used to look at these trees and they will give, without the bark on them and a number of missing rings that you just get a very variable date. Typical dendrochronology. You don't have a solid date. Also, the Ute tended to pick up dead wood that had been around a long time. It is a pretty dry environment out here in the west, so that stuff lays around and yet when they metal detected around them, lo and behold, they turn up tinklers and projectile points that would suggest mid to late 19th century.
In fact, Curtis has found stuff we know the Utes were all driven out of this area in 1879-80 after the Ute War and placed on reservations in far southwest Colorado and in Utah and they were never back again except Curtis has found evidence of Native American Ute occupation and use of the landscape as late as 1914. That is all based on the archeological record of metal objects but it is changing perspective.
Another one that I got my nose stuck into and of course I can't get away from George Custer. We looked for - with Peter Bleed at the University of Nebraska - looked for the Hunt Camp of 1872. The guy there on the right is Grand Duke Alexei of Russia. He was a sailor and on a world-wide diplomatic mission and also learning to be a confident naval officer in the Russian Imperial Navy, he was sailing around the world, he stopped in the United States, went to lots of different places, Niagara Falls, New York City, Washington D.C., you name it, and Chicago, and lots of other places, and ended up in the West in Nebraska during a buffalo hunt with General Sheridan, George Custer, Buffalo Bill, and a few other dignitaries. They were showing him a good time. They also brought in Spotted Tail, the Lakota leader and about 600 of his folks and we knew this environment was pretty pristine out there, we hoped that it didn't have a center pivot on it, irrigation system, and it didn't, it was well preserved and we were able to find cut nails and tent pegs and here are the lead foil seals from the champagne and wine bottle that were ... It was a big party!
The metal detecting found that. We talked to a couple of collectors that had been out there before us and they had found nails and didn't think they were anything, just a homestead thing but we saw the nails that we were finding and realized, no, these were small framing nails and light construction. What we did have, we grafted the site as well and the one on the lower left is the Grand Duke's tent and his accommodations had a stove in it and also a wooden floor. What were the nails used for? They were used to floor the dining tent seen in the center with Spotted Tail that were used to floor the Grand Duke's tent and possibly General Sheridan's tent and these things were all concentrated in one area and when we overlay the landscape, they fall right into place, the archeology is.
Karen: Doug, can I break in. I’m sorry. People, can you please, please, mute your phones. People! I don't think they are listening to us. I apologize, Doug. People! Can we ask you to mute your phones, please.
Doug: Yeah, whoever is talking about gun tools, I am excited but save that for later.
Karen: All right, please go on. I'm sorry.
Doug: Anyway, with this Grand Duke's hunting camp, we were able to reconstruct it, based on the archeology and actually place the tents on the ground using Google Sketchup - now Triple Sketchup - as an example. What we are doing is taking the physical evidence we found by metal detectors and are able to build these larger constructs with them. It is not just about finding artifacts.
The next case example I would like to use is Pecos National Historic Park where we worked with Sue Ainager, Heather Young, when they were both there. They’ve now moved on. Also, Charlie Hacker, he is a guilty party in a lot of the stuff that I do in metal detecting. We did not detect around the pueblo itself, but of course I would love to because AV Kidder’s laboratory shack is there. We did, through the University of Nebraska with Peter Bleed, work that area and our goal was to locate evidence of Spanish Colonial and later trade with the Pueblo and Comanche and Apache who were coming in from the Plains to trade with the Puebloans. We had a 500 year level and you can see some of the students out. We used fairly wide transects because we were looking to get a sample of the area. Here are some of sample plots, staying away from sacred areas and also from the Pueblo proper. These have been lined up based on possibilities where Apache or Comanche campsites and/or other things might have been happening. This is the so-called trade fair area where, supposedly, trading activities occurred outside the pueblo in this little flat area out here.
We metal detected there for a little while and we only turned up about 1,800 metal hits in 10 meter wide transects. We narrowed some of them up in some areas. The interesting thing about this is that this large block survey is really, really important. For something that is not supposed to have much metal in it because these are prehistoric pueblos of great time depth, there sure is a lot of metal out there. Our sampling procedure is that we plotted in every hit regardless of what it is and then we only could excavate 20% of that sample, so we used a random number generator to decide what we were going to dig of any given transect. Then we were only allowed to collect 20% of that, so pretty judicious sampling, at least with the collection process.
Interesting thing about this, it shows you there is more of a modern, last 500 year imprint than probably anybody ever thought and certainly a number of those big black clusters down in here are probably beer cans from the Pecos Conferences and other activities from when it was state park. Certainly most of the modern stuff [but we did find a few kind of interesting things. I won't go into the specifics of where but we did find some knife points and knives and those are Spanish Colonial knives. We found Koscohos, parts of dangles off of bridles. These two are definitely very early colonial Spanish. This one is much, much later based on XRF analysis and it has a lot of late 19th to early 20th century alloy in it so somebody had something out there pretty late. We've done XRF on almost all the metal out there that we collected.
We did find this, and several of these which are hair-head horse shoe nails. They went out of style about 1568-1570 not that they couldn't have carried on a little bit longer. The first contact with the Pueblos was 1540, 41 with Coronado. The next contact is 1598, this is probably solid evidence of Coronado at Pecos. It wouldn't have been found otherwise without a metal detector. Nothing, again to speak of, on the surface of this site indicating any metal laying around. We actually have additional evidence of the Santa Fe trail out there, very strong evidence of that as well as some campsites associated with the Apache and Comanche and Glorieta Pass, the battle of 1862 that helped decide the fate of the West as far as the Confederacy was concerned, keeping it in the Union. There is a coalition of great time depth here that had to be sorted out from the metal typology as opposed to its stratification which is not existent for all practical purposes. Almost all of this stuff was found from less than 10 cm deep.
Other metal detector applications in archeology are using them in excavations. This happens to be one from Little Bighorn again but we use that as a metal detector, once we start an excavation, we make sure we weren't missing something of metallic importance. We were screening, of course, but things do get missed. Another application here, digging a military dump-site. We were missing very small nails and things from saddles and others with a quarter inch screen so we were running everything over a metal detector. And notice we aren't swinging the metal detector, we are using a move called a pinpoint mode and having just dropping the earth on top of it, it won't hurt it. We are able to get greater recovery of small objects that will tell us again what kind of activities have been occurring associated with that particular dump.
Here is my other shot on underwater archeology. You can use these machines, depending on the model and type, in water. The coils and the antenna or wire, or connecting wires are usually sealed systems. Not every, you have to check that out before you purchase one but you can use them. Also, notice how this coil box is being worn on the hip, it can be detached from the detector. Some you can, some you cannot but you can work in water fairly easily with most detectors but you always want to make sure to check the manufacturers specifications on that kind of stuff.
I'm going to move to a couple of forensic situations to show you how we've done some of these things and applying them in a number of different ways. This is a mass grave exhumation done for the International Committee of Missing Persons and Physicians for Human Rights in conjunction with the United Nations and the International War Crimes Tribunal in the Hague. This is done in the early 90's. Cal Calabrese and Ralph Hartley and I and Melissa Connor were kind of lead archeologists on the thing working with an international team of forensic anthropologists and a number of others from Belgium and a number of other places. When we found the mass grave, we plotted all of the cartridge cases to determine whether or not there was a pattern there because the eye-witnesses said that it was an execution. The Serbs, in this case, said, "No, no, no, it is something else entirely, we didn't shoot anybody." Yet, there is all sort of AK-47 rounds there, they are in a pattern based on the extraction patterns of that particular weapon that would indicate these people were lined up on the edge of the grave and shot and then people went into the grave and actually administered coupe de gras shots from a 9 mm weapons.
The data was there and we've used them in actual grave exhumations where we are checking to determine if there are bullets or jewelry or watches, credit cards, anything like that that might be affiliated with the body to help make a positive identification or presumptive identification that can later lead to a positive identification. This is, again, work in Croatia where you just literally use the detector in the grave and on the body. We did find in fact, billfolds and wallets with credit cards and other identities underneath the bodies in some cases.
Another one dealing with firearms. This is a murder investigation in Colorado where somebody was shot and the metal detecting along the side of that hog barn indicated where the white dots are the shotgun pellet pattern. You can reconstruct that the person was standing back here somewhere based on the pattern of the shot pellet distribution. This would not have been good for magnetics, obviously because you are right up against a metal building and you have a metal feed bunk back here and it would, this would be a case where metal detectors, which can work with in and very very close to metal objects within a meter or less is a good example of what you can do with this thing. We've used this on a battlefield as well, looking at distributions of canister, shot gun pellets from shot guns or break and ball loads and things like that.
I'm going to conclude up with a couple of statements and again, I will be happy to take questions. Metal detectors are pretty darn useful tools. I think we, as archeologists, there is still some resentment and some residual feeling that maybe they shouldn't be used but I find them on historic sites to be absolutely the most effective tool for determining boundaries, I can do it quickly, I can do it easily, I can teach others to do it pretty easily. You can define site boundaries based on the distribution of metals. You don't even have to dig the stuff up. Like at Pecos, we were able to see large masses of stuff and using random number table generators, sample it, and determine how much of it was modern and how much of it was older. The density of metals allows for more efficient excavation or other sampling to planning and it is tremendously more useful than shovel testing on metal-bearing sites.
I'd like to point out if I had to do shovel testing at the Little Bighorn at a 5 meter spacing over the area that we did in all those years of working out there we would have dug 45,000 shovel tests. I'd still be there and we would have found according to when I laid the array over the actual artifact pattern that we had, we would have found less than 50 artifacts on that particular site by using traditional shovel testing techniques. Metal on historic sites, metal detectors are a far better tool than shovel testing. It doesn't rule out any other archeological method but it is an enhancement that allows you to be better able to place them.
The important thing to know is that metal detectors only can be used on sites that contain metals. This is sort of a "duh," it's obvious, but they are only relatively shallow depth penetration. As I mentioned, some of the new pulse induction machines can go as deep as 3 feet and find really small objects, so that is a different story but you have a very significant investment in costs. The coil size is partially dependent on depth, 8-11 inch coil will get you 30 cm or a little bit more. On a consistent basis, smaller coils will go somewhat smaller, larger coils will go deeper. Like any other electronic tool, the larger your size of coil, the less resolution you get going deep unless it is a pulse induction machine. Those are important points to remember. That is pretty much the end of things as far as what I wanted to say.
A couple of addendums, if I can. One thing I have been surprised at is what I believe to be and perceive to be, the lack of interest in archeologist in applying these on sites in the potential copper bearing sites up in the Great Lakes area. Looters are doing it and they are finding the copper producing sites and also manufacturing areas. I don't understand why archeologists haven't said, "This is the tool to find some of these things and understand how this stuff is being produced and then moved into the mound sites and villages and so forth." On the other hand, I do understand the reluctance of some people based on things happening in the East. The dyed in the wool looters out there particularly on Civil War sites. I'm a big believer in using volunteers but I've only had one really bad experience in over 30 years of doing this and that was dealt with fairly easily. I do get it that other places don't have as nice of people as I get to work with.
There's a lot going on, there's a lot of ways to do this. If you are interested in metal detectors and purchasing one, you can lease them. I really suggest that you get in touch with a local metal detector dealer. They will know the soil types in the area. They will know what machines work the best with your environment. There are machines that work across the U.S. across the world and if you have questions about that I have enough experience that I can be happy to advise you. Drop me an email or something, I'd be happy to help you. I don't, there are certain brands that work better in some places than others. I'm going to shut up and let you guys ask questions or escape, whichever you like to do.
Karen: Thanks very much, Doug. Do we have any questions? Well, I have a question. You had talked earlier about the difficulties or the fine line that you have to walk between using volunteers and that messages that can be sent or the way that the public is perceiving archeologist who use metal detectors. How - do you any advice for us on how to negotiate and navigate that?
Doug: Well, I can give you my own personal experience, which is: we very carefully vet anybody who comes, we don't just say, "Hey, just come on out with us," we ask to apply and give us a little bit of background. You can usually tell in a conversation with an individual whether or not they are trying to milk you for information or use you to figure out how to sneak into that site. There is just body language and the way they say things that you know that they are not going to be a person that you want to be around. That is learning how to deal with people of course.
I've found many many people who are very trustworthy and I personally have a group of volunteers that I like to call on to be a core group. They have worked with me many times and they will then work with the newer volunteers that come in from say, a local area and those individuals very often do not detect unless they are on a site with a professional archeologist. The ones that I have as my core group are not hobbyist, they want to do this because they really want to contribute to the archeological world. I've built that cadre up over time and those folks acting as a core will also help me monitor the others out there. First of all, I trust that core group and they have spotted people, not stealing or anything like that but maybe you question whether or not the ethics are really there or if they don't want to follow directions or something, you learn how to work with them a little better.
Again, I've used volunteers on digs before and not just metal detecting so I am a big believer in that because it gives the public, people can say, "I was on this project," and in a lot of cases with these metal detecting, I think when these metal detectors realize professional archeologist respect their capabilities, not necessarily whether or not they collect, that is another issue, but they respect their capabilities using that they are going get to work in places they would never be allowed in otherwise, with good reason. Then they can say that they helped discover and preserve the past. That sends a message out to other hobbyists as well. We're not going to convert everybody, I know that, but if we can convert a few, that is a big step in the right direction so I don't think we should ignore them. There are places and times you don't want to use them, I agree with that, absolutely. Other times I think it is a great PR tool.
Karen: What is the allure for metal detector users to volunteer if they can't keep the things that they are finding?
Doug: Just a personal viewpoint, I bet that 80% of those people don't really care whether they keep something or not, it is the thrill of being out there and doing something outside and altruistically, some of them really want to help archeology and understand the past. Others, it is just great fun to be out there and when they find something and see it and take a picture of it, that is cool. They are happy with that. I bet that is probably 80%. There are the dyed in the wool people who want stuff. Those are the people that I don't want around.
Karen: Well thanks very much for being so candid about that. It's always been a tricky issue for me to understand.
Doug: I think it is a tricky issue and it depends on where you are. Folks I have talked to back Southeast with John Cornelison and many others with issues on battlefields and other historic sites where people are looting left and right, it is a different story and I think it has to be treated differently. I wouldn't want to go down there and get a bunch of volunteers in without having somebody else that knew those people well.
Karen: Do we have any other questions? People who would like to make comments?
Michael: Yes, this Michael Peterson, archeologist with Redwood National Park. Hi, Doug.
Doug: Hi, Michael.
Michael: It's been a long time since I have visited with you. I have a complex question I suppose but could you address - one of the things that I would consider when you were extracting - say you find a piece of metal with your metal detector and taking care of pulling it out of the ground, depending on if you are in a plow zone or in a virgin sod, what type of considerations do you do and what is some of your methodology?
Doug: I think you just said it. It is the context where we are digging in, whereas a hobbyist isn't going to understand that at all or largely won't. We, as professional archeologists do and so once something is in a plow zone, a little less, it's been disturbed probably. Taking it out, most everything that I do has been GPSed in but actually digging it up, a lot of times you set a target, you go in, you find it, and you recover it with the smallest footprint of disturbance possible. We've gotten a couple of cases where we have gotten down on something and we realize, "Whoa! This is something else, this is bigger, we have more context, there's other things around it," so we will halt that metal detecting part of it as far as recovery concerning a small hole and go to a formal excavation unit or test unit or something like that. It is all about context and
knowing what you are likely to be recovering. We work in Big Hole, Montana, in the Native village there that was attacked by Colonel Gibbon in 1877, we dealt with, specifically, what we thought were specifically tipi stars, we were looking for patterns of stuff. We got into beads associated with metal objects and stopped and opened up a test unit in there to determine what we had and that worked out real well. Context, context, context.
Michael: Thank you.
Karen: Do we have any more questions or comments? No? Well, thank you all for joining us today and we invite you to come on November 6th, a Wednesday when we will have another webinar for archeo. In this case it will be an archeo-Wednesday. So enjoy your week, everybody.
Description
Douglas Scott, 10/24/2013, ArcheoThursday
Duration
59 minutes, 46 seconds
Credit
NPS
Date Created
10/24/2013
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