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Gray's Reef National Marine Sanctuary; Fossil diving  

NPR/NGS Radio Expeditions
2 Jun 1997

    Geography
  • United States
    Georgia
    Locality
  • 32.0 km E of Sapelo Island; Gray's Reef National Marine Sanctuary
    Latitude/Longitude
  • 31.4   -80.93333
    Habitats
  • Marine
  • Ocean
    Channels
  • Stereo
    Sampling Rate
  • 48kHz
    Bit Depth
  • 16-bit
    Recorders
  • SONY TCD-D3
    Microphones
  • Sennheiser MKH 30
  • Sennheiser MKH 40
    Accessories
    Equipment Note
  • Stereo=1; Decoded MS stereo

NPR/NGS RADIO EXPEDITIONS
Log of 2way with Erv Garrison and Chris Joyce
Gray's Reef


DAT #2
MS sennheisers 40s and 30s. inside the Rycote with a (rat?) .. into Sony D3.

1:37 -start of 2way

CJ -tell me why you have to wear gloves to touch these bones?

EG -~they are scientific samples and they do undergo examination you have got stuff on your hands, mostly just sweat and one thing you don't want to is you are doing any chemical examinations even though we do pre-treat the bones when we do the things~..we treat them with a little care and gloves seem to be just a small price to pay for handling fossils.

2:37 CJ -so let's have a look at these bones and see what they tell us.

EG -alright. We will get your favorite out here and we will bring out one of the latest ones that Bruce Caldon had found. (looking around) this is the bison medapode (?) that we talked about before. It seems to be the least fossilized of the bones if you compare the real dark pacnation (?) and heavy fossilization of this bone as opposed to this one. This one still looks pretty much like a bone where this one looks somewhere btwn a bone and a rock.

3:16 CJ -now what part of the bison is this?

EG -ah. It is actually the medapode or the foot of the -towards the hoof. It would be articulating then with the what we would consider to be fingers, this would be articulating with the hoof itself~.which I supposed is a modified finger. You can see the articulating surface here -this is I think one of the nicest fossils we have found bc I think most people can look at this one and immediately say -"oh!" we don't have to -you know -we hold this one up and say, you know, name this and someone might say well, that is just a rock. But if you look at it closely you can see basically the same kind of architecture as the bison bound -you have got a -the interior portion here which is concave and you know -you can visualize completing the bone and then you got a smoother exterior here. It is a good fossil.

CJ -you are diving 60' under the water. It is visibility is probably not very good. There is sand, there is silt on this stuff. How can you possibly pick this out from the rest of the stuff on the bottom?

4:40 EG -I guess you are cueing on certain elements. You are cueing on shapes. I know that Bruce and reed and I maybe not so intuitively but understand that there are certain shapes in nature that aren't found very often. I think bones and fossils represent a shape that we don't often see on the bottom of the ocean. So we can be fooled. There are a couple of items in this bag which clearly (bg: rustling through bag) could be construed for instance -is this a bone or is this a rock -or what is it? As opposed to this where there is absolutely no question but there is enough ambiguity in this particular piece that we have to pick it up just in case that it might be a fossil. But I think it is just the difference that we pick on. John Van Newman who is the great theorists on the mathematical theory of communications is not the noise we listen for -it is that little peak of information -and it is the difference to all of the sound we hear at anytime. So maybe this is the visual equivalent of that anomaly that stands out that carries that bit of information. 6:17

CJ -let's go back a little bit and talk about gr as an archeological site. In essence, the way I think of it is as a time capsule.

6:47 EG -gr is a portion of our most recent history and I think I am talking in the geologically sense in the last 50 to one thousand years. And not so long ago, again from a geological sense of time that was open grass land with probably trees and animals that clearly these fossils represent and maybe humans so -what we are looking at is just another potential area for archeological finds except this is 60 ' underwater. But again at gr I think you have to realize that you are not going to have as much disturbance of any materials out there except for what mother nature is doing. So these materials may still be what we call NC 2 or in place. They haven't been moved around by human agency -they have certainly been moved around by mother nature. We would like to think that they haven't been moved around that much. The thinking that we have about these particular fossils is that they have probably been redeposit, eroded out of the sediments that were laid down several thousand years ago. We would like to find them in the sediments before they are eroded out so that is kind of the next level we are going to do but now we are quite pleased that we have been able to demonstrate that land animals once lived at what is now called gr.

8:45 CJ -And the fact that it was land and then fairly suddenly in geological time it was inundated and covered possibility of finding things pretty much the way they were.

8:59 EG -exactly. And I don't know the land at gr is that much different from land let's say that is 60 or 70 miles inland -let's say the area that is west of Savannah. But going on what we know, the animals that are extinct now -even this bison, and certainly the mammoth and certainly the horse we could suppose that the landscape itself was fairly different as well from a botanical standpoint. So any info we get is -we are looking at trying to focus on a paleolandscape that we don't have any modern analog for -and it is as I say just 20 miles off shore as opposed to something that might be under a salt marsh or under a house in Savannah.
10:00

CJ -now you think that it is possible that people lived there -10, 12 thousand years ago -think you might find some sign of these people when you dive?

10:13 EG -well, that is always the hope bc right now, strictly speaking we are dealing with more paleo-environment and paleontology. We don't have an evidence of humans. We have got the right species. It has been well documented that humans from 12 thousand yrs ago selectively sought out bison, selectively sought out mammoth and hunted them and even horse. In Europe we found that the Pleistocene hunters there liked to hunt horse -so we got the right animals, we just don't have any evidence of the humans yet. My graduate student is constantly looking at these bones for any evidence of butchering marks were a stone tool might have slashed some cartilage or some tendons to get the muscle off the bone. But it is fairly evident if you look at this bone that there is no cuts or scrapes or anything on it. And most of the damage I think on these have been done by maybe burrowing worms or encrusting organisms. That is one thing we know that the bones have been exposed from their original deposition bc now they have got these little sea critters -briazoans and things encrusting on them.

11:42 CJ -what tipped you off that gr was more than just a biologically interesting place and had potential for an archeological discovery?

11:53 -EG -well, word got out in the ~80s of some finds from the Dept. of Natural Resource divers. I was at the time at Texas A & M. I had a colleague working as the archeologist for the mineral management service which is a branch of the Dept. of the Interior and she had mentioned to me that she had heard about these finds of fossils from Georgia. We didn't know exactly where. And when I went to go work for NOAA in 1990 I got interested in -I started pursuing this along with other elements of my job and I was curious about -well how close were these finds to the gr site? I couldn't get any response on that and we just let it go at the time. But I never forgot about the fossils and Georgia. So when I came to the University of GA in 1992 first thing that Reed Bohne and I did was to resurrect this fossil find story and try and track down the source~ we verified that they (Dept. of Interior, etc) had actually found fossils -mammoth teeth from about 10 miles north of gr. So then we put together the hypothesis what makes that place so special and why couldn't there be fossils in gr itself. The opportunity presented itself in '94 and '95 to begin a search of the site. We did go to j reef which is the area where the divers found the original fossils. But it is like a beach. It doesn't have any outcrops, it doesn't have any live bottom so to say. Then we came back to the sanctuary and we do have some structure -we do have seemingly the same potential. And then Bruce Coudon from NOAA ship Faroll, and Reed Bohne in 1995 made the first discovery of a real living fossil -it wasn't a living fossil, but I certainly was an example of a fossil bone which had certainly been in the ground for a long long time. We don't know how long but then it seems asthough where it rains it pours. Were there was one we found two, we found three, and then all of the sudden this box started getting full.

15:03 CJ -now which one of these was the first one?

EG -the first one is this little guy -you can see it is dark -but it is a smaller bone as opposed to this larger piece. It is a much smaller bone.

CJ -what kind of bone is it?

EG -we are not sure. We have given it to the experts at the Museum of Natural History and Gainsville, FL. And they are not too committal. They say it -when we had originally given this to a paleontologist just at GA. They said -well, it could be -BOAT PASSIN~.

16:51 CJ -you submitted this one -and then what happened?

EG -they were pretty non-committal whether it was a land mammal or a marine mammal. And I can understand that. There is not a whole lot of difference btwn lets say the ribs or bones of a porpoise or a dolphin or a deer. They are both mammal. They both have basically the same architecture in their bones so -and this is not a very large sample. It is only a couple -3 inches long. We did submit it to Beta -Analytic Lab in FL for carbon dating. And they did say it is too old. There is absolutely no collagen left in it so it would be a waste f time -but by telling us it is a waste of time we are assuming it is over 50,00 years. So we got a little info out of it but then the bottom line was to go back and find more fossils maybe some that were a little less opaque in terms of what kind of species they were. So then we started finding these bones which you could speciate, you could determine what the animals were so now we know we are dealing with mammoth, now we know we are dealing with horse, now we know we are dealing with bison. Let me see if I can get the little horse -well it is not a little horse tooth, it is a good size horse tooth. But on a scale of 1 to 10 it is probably a small horse tooth in comparison to what we are dealing wit~.horse~.queue the horse~queue the horse .. here it is. So, it is fairly clear that it is a well formed, well preserved, Pleistocene horse. 18:52

18:53 CJ -now this is maybe 2 inches long and an inch through. It is about the size of a piece of ginger root except it is black. I don't see how you can see this on the bottom.

EG -good eyes I think. Bruce and Reed were certainly ¬well, I am impressed with their ability to pick these things out (WAKE HITTING BOAT). The bottom helps us out a bit bc it is sandy, and if these things are lying there on the sand -BOAT WAKE STRONG -(again) the bottom helps us bc it is sandy and if these things are lying against that white -sort of white bg they are pretty starkly contrast. Even this black. If they were lying on the gr rock they are a little harder to see. Now, my guess is we would have a little bit more difficulty if they were on just the reef rock. This brown guy -he is clearly ¬you could see him for 10, 20 feet away and not mistake him.

CJ -You have done archeology on land, on lakes, and anthropology -how is it different -can you get what you need to get 60 feet under?

20:29 EG -There is not much difference from a methodological stand point of doing archeology on underwater and doing it on land. I always liken it to ¬you put on air tanks to get to the bottom it is kind of like getting in a pick up truck and going to a site. You are just in a boat and using air. Once you get there you are doing the same sort of thing and you have the same care and the same care and the same rigor, you just have a little more of a time limit. You know that tank on your back is only going to give you about 1 hour and you better do what you are going to do w/in that time. I think another thing it does -it does tend to focus on your job a bit more carefully. So you don't waste a lot of time down there, everything is planned before you get in the water and then you maximize your recovery and so when you come back on to the boat you have something to show rather than just an empty tank

21:31 CJ -If people lived on gr when it was on land, before the sea level rose who would they have been and what would life had been like there?

21:41 EG -the analogs from what we know from the -what we call the paleo-indian sites, or if you want to use a more general term, Paleolithic. These Paleolithic hunters were migratory they followed big game animals. They probably followed in small bands of a couple of 3 families, probably not more than 25 people. They were highly mobile. They were probably very well organized. They were probably organized according to kinship. A stranger was a non-kin BOAT PASSING -23:02 strangers to these groups would be non-family members. So I think the groups were pretty much all related in some form or another. They hunted these animals. We have got evidence of their sites were mostly all we find are their tools. We find their spear point we find the materials they used to process their kills with. We found precious little -other than the more durable goods. There are rock tools. We find precious little bone. We never find any organics but that is be most of the sites are out in the open. The hope is that perhaps at a place like gr if there are sites where we do find the materials or remains of these hunting bands then we might find more than just the rocks. We might find evidence of their shelter, we might find evidence of the kind of plants that they collected. We know they just didn't eat meat. They had to collect wild plants and foods. There are a lot of pieces of the puzzle that we don't understand about these people. We do know they were probably the best hunters the world had ever seen.

24:22 CJ -what makes you say that?

EG -well, they tangled animals that I wouldn't even get near in a car. It is something about going one on one with an antique bison which was probably half again as big a modern bison with a horns that probably went 6 feet across -that is -just doing that with a spear is -I would say not many people would do that today.

CJ -big cats?

24:52 EG -big cats. Big teeth (CJ -saber tooth?). yeah they were saber tooth. Dire wolves probably scared the saber tooth. And then there were such things in Europe.

25:12 CJ -what about predators on the coast of GA.

EG -well, you had the sabers. I don't know -~I don't know about the cave lions and their distribution in the new world, but certainly you had the large bears. You certainly had the dire wolves, you certainly had the saber tooths -there is a whole host of predators that were available and the competing with humans. Different world really.

25:44 CJ -now you are also taking cores. You are trying to find out what the environment was like -what the weather and the plants were like.

25:53 EG -yeah. We have a couple of things here. These are kind of the tips of one of the cores we took out at jay reef. The geophysical surveys we do before we take the cores is basically just to characterize the sediment so we know what we are coring into or have an idea. And so we have taking 10, 12 foot samples of which this is just the tip of one.

CJ -can you describe this one for me?

EG -well this one started out as a 3 inch aluminum barrel. It obviously has been flattened on one end. Much like you would take a soda straw and after you have sucked on it for too long, this is kind of the aluminum equivalent of that. So it is flat. And probably due to the fact that it struck something as it was being inserted. But we do see a continuous record of sediment starting here and then were it is trimmed off there is another 3 feet of the sample which has been undergoing examination back at the University by one of my grad students who is writing her masters thesis on it. But what you see on it is some real fine grain -kind of a greenish brown sediments. It is mostly silt. And in the silt you can see some -a few shell. It seems to be laid down as a package, or what sedimentologists call as a package -which means it was probably laid down in events. This looks to me like it is pretty much all the same material all the way to the tip. Now you can get dramatic changes and we do see less silt, more sand -almost grating into shell hash. To silt back to sand, like mus. And what those changes tell us -it tells us about changes in the deposition which is probably linked to the paleo-climate. The changes in the changes in the sediment is directly a proxy of climate. You have to get inside these cores and to ring as much info out of them as we can. Like one of the manganese is an element that we try to extract chemically. And manganese is a proxy for the amount of the oxygen that is in a sediment. We can't get into the 02 bc it does what all 02 does, it oxidizes like crazy. But the manganese is bound to the little particles-MORE ON THIS- it tells us if there was a lot of 02 -and what does this tell us? It tells us that it probably a kind of an estuarine environment where most of the rich biota extracting the water -still waters _ and not leaving a lot for the benthic organisms and certainly it is not being demonstrated in here. This is probably an estuarine environment -much like you see -if you could go down and grab some mud underneath this boat and dried it, it would probably look much like this.

29:34 CJ -And yet you can tell that this is 10,000 years old and what you bring up today is current.

EG -Exactly.

CJ -what about evidence of actual organisms in there?

29:46 EG -Organisms -about the only organisms that you find -of course you find the shell and if you got a good malocologist or someone who knows the shells they can maybe get a species out 0 them. One thing with the hell is that we can actually get a date. So we can physically date the carbonate and we can get a reasonable date -a radio metric date for say -this level in the core. The little animals -like the little benthic forams, foramanifera, which are again little shelled animals which are just a few -oh -sub-millimeter sie. They are in here and if we can extract them, put them under a microscope, foram specialist can tell you in a heart beat, well, were these forams living in a salt marsh, high marsh, low marsh, were they living in an estuarine, tidal environment, an open beach environment, open sea environment. So there are so many different species of the little forams that you can get a good sense -it is almost like saying -holding up a flag and saying this was an estuary or this was a beach.

31:00 CJ -So, in addition to the fossils, the sediments -these things are all like time capsules are telling you what life was like 12 thousand years ago.

EG -umhu and here you have what we call a macro fossil and of course the little forams which you can't see those are the micro fossils. We also try to extract fossil pollen from these things. And we have been very very lucky at gr in that we have been able to extract wood _ hand that to any wood specialist like we sent to~.. he can immediately take a chunk of that and say ah -you are dealing with a chunk of spruce ~.. he probably doesn't even use a microscope for that. So again we have been very fortunate that the sediments have preserved these organic materials so we can get at the ancient environments. So we are getting a pretty good picture what life on the GA coast might have looked like from 50 thousand yrs up to around 6 thousand yrs ago. Lots of gaps yet but that's why we keep going back to the reef.
32:17

CJ -you had an interesting term for this yesterday ¬

EG -dirtsicle? Basically cores are nothing more than dirtsicles. You split the barrel and you look at them and you just got this long column of muddy sediment but to sedimentologist or marine biologists that's gold. Bc he knows how much info is looked up in that dirt

32:50 CJ -one other thing on the geology -how often did the coast line move back and forth over the last 100 or 200 hundred thousand yrs.

EG -that's a good question. I guess it depends on how you want to model it. We know that at the peak of the last glaciation starting somewhere inside of 40,000 years and then peaking around 18, 20 thousand yrs ago. The sea was in pretty rapid regression. In other words it was going down probably a meter or more every 100 yrs and it reached a low stand at probably more than 100 meters below what we recognize today. So gr is only 20 meters water depth so the sea the beach was several kilometers seaward of what gr would be. So it might have been as far as 60 kilometers. So gr was inland. At probably 18 thousand. So the sea reached it's low stand and as the climate started to warm up and the glacier started to melt and all that water started to pour back into the ocean this is where you get into the question well how fast did it rise, did it rise continuously? Did it start and stop? where there periods when the ice melted faster or slower? did the ice even stop melting for 100s of yrs at a time? I think I tend to come down on the start stop theory. The evidence that we have been getting out of the gulf of mexico and some evidence that we have gotten north of here up toward Delaware has been that the sea would rise reach a level -maybe it would rise 20 meters -stop for a few hundred yrs -rise again -stop -rise again -so it is sort of a punctuated sea level rise. The over stepping -it is term that people who study sea level -the over stepping of the beach -you know the beach is flooded and then the waters tend to move over the land -how fast was that? Probably you didn't have to pick up and move very quickly. Over tens of yrs. So people had plenty of time -and say, well we can't go back to the beach. The beach is under water. But there wasn't any great catastrophic flooding of the coast. As we would picture. So even when it would move rapidly in a human scale it wasn't all that rapid. 35:51

CJ -name ¬

35:55 -EG -I am Irving Garrison, associate prof of geology and anthropology at the U of g in Athens -

AGAIN

36:43-38:13 -IRV PUTTING THE FOSSILS AWAY

38:14-41:32 AMBI AT PLACE OF IRV INTERVIEW

(motor boat passes by, wake hitting the boat)

40:17 -big wake, 40:56 big wake

42:07 CJ -NMS -his work connection:

42:17 EG -gr is a marine protected area which means there are certain advantages to that. We know what to expect 365 days of the year in terms of access, in terms of support, in terms of allowing us to do our research ¬which we have to have a NOAA permit to do so -we could go, I guess elsewhere on the GA coast but I think one of the missions of the Sanctuary program has always been to facilitate research. And our research not only adds to the understanding of gr it adds to the greater understanding that we are trying to find out early human occupation of the new world. So it fits like a glove.
43:15

CJ -and one of the things that makes gr unique and special is that it is the only Sanct. Where people may have lived at one time.

43:26 EG -when I was working in the sanct. Program we had looked at sites. We had looked at the Channel Islands as potential sites for early habitation in that part of the us. And I not convinced that we wouldn't have found it. It is just that here in GA we have been able to find direct evidence of at least the animals and certain preserved paleo-climate indicators like I say the sediments and the micro-fossils. So it is just the luck of the draw. But there is something to be said -I think Sanct. Are created bc they are special places. I have always had a friend at the American Museum of Nat. Hist., David Hirsh Thomas, that always said that places that are special in today's time may have been special in the past. So we are not necessarily discovering something new in gr. We are rediscovering why they were special in the past and maybe we are just following along what our ancestors may have known about the landscape.

CJ what was it that you think drew people to this place 12,000 yrs ago?

44:53 EG -well, if I was a hunter and I was going to look for game I would go to some place that was an elevated piece of terrain. It was probably an outcrop _ which we know that this place is an outcrop -and we might have been able to survey the surrounding area -the surrounding plains. We know that there were some river channels around here. We know that at jay reef was a major river valley. So yeah -that is where the animals are going to go and probably the humans did too. It is probably important in the sense as a good place to just be.

CJ -Now of course it looks very different. So when you
go over the side what do you look for?

45:44 EG -well, I look for again -can't waste time underwater -so we are looking for fossils. So we start surveying for new fossil finds. We don't pick them up. We immediately start to just id them and then we come back, we map them in with tape and a compass. Then we can collect them. But in the back of my mind I am trying to visualize what kind of landscape was here. Every time I go down there I get a fresh understanding about what this place may have looked like 12 thousand yrs ago, 50 thousand yrs ago -in other words I have to take my mind back. And the only way to do that is to be there. It is something about being in immediate contact with the landscape itself, even though it is under 70 feet of water down ¬-

46:41 CJ -so you have to train yourself in a way to imagine what you are seeing looked like when it was dry land

EG -exactly. It is very difficult when you have sponges staring at you all of the time

CJ -at least they don't move ¬

EG -they don't move -no . and if you just squint real hard through your face mask they might look like flowers -LAUGHTER -47:02

47:03-47:29 -AMBI -WAKE HITTING SIDE OF BOAT

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