Robin McLachlan: Alright well let's go ahead and get started and i'll introduce myself, my name is Robin mclaughlin.
Robin McLachlan: And I am a geology professor at the College of coastal Georgia my expertise is in coastal sediment dynamics and coastal ortho dynamics.
Robin McLachlan: And, along with my colleagues, James Dini kimmy to him to Connie and.
Robin McLachlan: damon gannon we have put together a field guide of the Georgia barrier islands, focusing on Central Georgia.
Robin McLachlan: And if you haven't yet, please do take a look at our GIs story map that's where we've created the virtual field guide for you to explore i've posted that link over in the chat it's also accessible on the GSA meeting website.
Robin McLachlan: And this session, I hope, would just be a time for us to ask questions discuss what we've seen meet some new people who are also interested in Georgia barrier islands.
Robin McLachlan: So i'll turn it over to my collaborator James Dini, let him introduce himself and then we'll just open up the floor to questions and discussion.
hi James steamy.
hydrologist comes a little water sunlight water resources scientist here at the College coastal Georgia and I been on the Georgia coast for about four years, so this was a great project work.
Robin McLachlan: Alright sounds good i'm not sure if our other collaborators are going to be joining us, I know they had busy schedules today, so if you have a question or comment feel free to put it in the chat or feel free to turn on your video turn on your MIC and.
Robin McLachlan: Ask it in fact discussion that way.
Michael Thonis: field guide is terrific.
Robin McLachlan: Oh, thank you.
Michael Thonis: I actually liked it so much that I showed it to my family.
Michael Thonis: So thank you.
Scott Harris: hi Robin.
Robin McLachlan: Please do share it far and wide hi Scott, how are you.
Scott Harris: doing well, I haven't seen the field guide yet, but maybe one day they'll see it, but I, like the storyboard and I was wondering what is your data set that you used for the annual changes that y'all put the Jeff up there, the gif up there.
Robin McLachlan: um yeah that is a fantastic online software that.
Robin McLachlan: Just auto if you if you give it the location, you want to auto generates the gift using I think land site ones that satellite imagery and I can post a link to that in the chat because I use it for everything I love it it's so easy to make gifts like that.
Scott Harris: that's awesome I love that idea.
Scott Harris: You saved me a lot of time.
Scott Harris: Later today but it's beautiful.
Robin McLachlan: Thank you.
Michael Thonis: Just for personal context.
Michael Thonis: Now, if you can see that.
Michael Thonis: But that's the Marsh.
Michael Thonis: At NASA on the NASA very a beach in Cape cod.
Michael Thonis: And it's a super high tide so actually the Marsh is being inundated.
Robin McLachlan: It definitely looks a little different than Georgia.
Michael Thonis: yeah i've been i've been to St to settle simon's at St simons island and and and.
Michael Thonis: And where's the where's the moisture that's.
Michael Thonis: What beaches what what island is that in Georgia.
Michael Thonis: The one that you can only get to if you make a dinner reservation.
Robin McLachlan: i'll see island.
Michael Thonis: Georgia right sorry blanked out.
Michael Thonis: But this is where i've inspector and covered here on this, we have a place that's right i'm a marsh behind the barrier beach it's a it's going to get what the place is going to get wiped out if we have another another foot or two of sea sea level rise.
Michael Thonis: But for now it's you know it's a nice spot.
Michael Thonis: I have wondered, it makes so you want me to just start I could just ask a question is that okay.
Robin McLachlan: Yes, please yeah whatever you like.
Michael Thonis: So i'm a question I have is these marshes.
Michael Thonis: And i'm guessing there's no answer but i'll ask me how I looked at my March and wondered how how deep is the Marsh I don't mean the water, I mean how deep how you know how did these marshes It strikes me is amazing that they are.
Michael Thonis: Totally flat, or almost flat.
Michael Thonis: That are quite horizontal but they're very flat.
Michael Thonis: And so, and then you know, so I mean I guess what is the morphology of a marsh it, but maybe that's outside the context of this, because this is about barrier islands, but they're kind of wanting to kind of join together at the hip aren't they.
Robin McLachlan: hey are so you're asking the depth of the mud of the Marsh before you.
Robin McLachlan: A one.
Michael Thonis: to one of the things that you have on your storyboard you feel guide storyboard is that.
Michael Thonis: Is that the the new dunes cover the old marsh.
Michael Thonis: And that's is that right, did I have that right.
Robin McLachlan: Yes, that's correct.
Michael Thonis: And here, right here in Cape cod very often after storms, especially in winter for sure.
Michael Thonis: You can walk on the beach and outcropping from the beach is old marsh.
Michael Thonis: It doesn't you know, for some, when you look at that outcrop it appears to only be maybe two feet thick and I guess i've just not been able to figure out what.
Michael Thonis: You know if it feels like the Marsh that that bars that's exposed that created episodically as as as contrast it to it having.
Michael Thonis: You know, build up continuously over 10s of thousands of years, it seems as though there might have been a time.
Michael Thonis: And you can see old carriage tracks on so that's been dated as being from the 1800s but it only appears to be a couple of feet, the pete.
Michael Thonis: appears only be a couple of feet thick.
Michael Thonis: which gives me the impression that it happened episodically and then further sea level rise has caused the dunes to be placed upon it.
Michael Thonis: As opposed to being hundreds and hundreds of feet thick.
Michael Thonis: So I guess i'm not i'm probably not being really good with the question it's a little bit of what's the Cross section of other did any of the barrier islands that you're working in what would the Cross section look like.
Robin McLachlan: it's a good question I i'm pretty sure I understand your question and that's not my expertise, but I can offer what i've seen from colleagues and their research and and.
Robin McLachlan: Scott might know this even better right but I the way I think of it as, as you said right the the Marsh growth is episodic and it also.
Robin McLachlan: translates laterally with sea level rise and fall and other events that change the extent of the Marsh.
Robin McLachlan: And so i'm assuming you know there it's possible that in the Center of the Marsh and between the barrier islands, you could get a very thick deposit of mud that very thick.
Robin McLachlan: very old marks deposit, but I think on the edges and especially where the Marsh is being consumed and being washed over and exposed on the beach I think we're getting those lenses that.
Robin McLachlan: As you know, the episodic migration of the Marsh again i'm not an expert in that so somebody else might have another idea but that's how I.
Robin McLachlan: picture the Cross section of the Marshall and I see those you know just sub meter thick marsh deposit on expense on the beach.
that's what I would do if.
Scott Harris: You know, it also.
Scott Harris: Michael I believe it is.
Scott Harris: If you'll notice in one of the images that they put up on the archie is that you'll see that their place to seeing barriers right behind the Holocene barriers, and so the place to seen.
Scott Harris: Is you know pretty close under now there are Paleo channels that have been mapped in that region that extend off shore but they're not that deep you know you do get some deep ones, and like Robin said, I think I agree that there are probably some thick sections where you had old.
Scott Harris: systems that had carved in when sea level was at the last play to a maximum and multiple lastly to maximum maximum.
Scott Harris: And now that that the modern system is riding on to that place to seen system, so you are going to encounter modern marsh and in a lot of places, you probably have placed the scene march right under it that's a lot more competitive.
Michael Thonis: That i'm here and.
Scott Harris: Now i'm in South Carolina in the sea island section, or just above the sea island section so it's a very similar vironment.
Michael Thonis: That does help what's behind say sea island or any Jekyll island or any of these islands that are referenced here there are there is a marsh in most in most cases right and.
Michael Thonis: And how I mean has anyone i'm sure people board down into those tools Martians right.
Michael Thonis: To see how thick the Peters before you hit.
Michael Thonis: I don't know sure what you hit not gonna hit bedrock well I don't know what, what do you yeah what is this photography as you go down through those marshes or if you go down through the as you as you go down or, alternatively, as you go down through the barrier.
Robin McLachlan: yeah you would eventually hit sand right cuz i'm so we have here in Georgia but also extending into South Carolina and Florida, we have these series of relics barrier island ridges that are now on land, and so the the modern Holocene deposits this mobile sand the modern Holocene.
Robin McLachlan: Originally, started to form barrier islands, at the end of the meltwater pulse during the last glacial maximum after the last lecture maximum melt sounds about 5000 years ago when the when these mobile sandy sediments were able to start forming bars.
Robin McLachlan: And as sea level rose following that they have migrated inland or toward the land and actually started to attach to and form around the pleistocene barriers and the most recent pleistocene barriers that silver bluff deposit.
Robin McLachlan: And so the the marshes are basically filling in between those two sandy your bars the to sandy barrier islands.
Robin McLachlan: And so, if you imagine if, when I imagine a cross section I think of basically a sandy basement or a sandy bottom that is formed by the barrier island whores and then in between those islands is where you get that marsh deposit in the back so.
Robin McLachlan: If I had to guess, I would say the deepest part of the Marsh is only as deep as that old channel bear island used to be.
Michael Thonis: Right, because you can't imagine there'd be a valley deeper than the see.
Michael Thonis: All the CMOs and further off sure at some point during this whole the whole the whole cycle right.
Michael Thonis: it's.
Michael Thonis: leaked out to death, my as my impression here on Cape cod or I think it's probably all policy or not always fair well it's it's end players to see policy.
Robin McLachlan: And that is familiar with Cape cod so.
Michael Thonis: yeah Cape cod is basically you know it's.
Michael Thonis: There are there was a.
Michael Thonis: It was continent okay so it's um.
Michael Thonis: You know what its shape is largely what it was, at the end of the pleistocene.
Michael Thonis: In the beginning of the whole see that's the overall shape of the case, you know it's.
Michael Thonis: It there are there are huge moraine and tilt Highlands that are being rapidly eroded away by sea level rise and and just bones, in general, combined.
Michael Thonis: But.
Michael Thonis: But there are large marshes there are really significant marshes here throughout the Cape and i'm guessing they're just they're all Holocene features that have to be that are just kind of built on top of an original topography.
Michael Thonis: Which i'm guessing is fairly shallow and these Martians probably aren't that deep but i've never heard anybody ever boring through one of these marshes they're all natural C sharp.
Michael Thonis: We have a barrier beach the.
Michael Thonis: beach, which runs up and down the entire outer arm of the Cape is one large barrier beach with some breaks through it and there are regularly wash others.
Michael Thonis: There was one right out here, I can't see it from the House, but you see it, we can walk to it just a you know, an enormous washer ever which most people have cheered because it's tending to I think well.
Michael Thonis: weld the beach, so that we don't get as many wash through because there's a big vein, so you get a break and it causes the bay level does the pleasant back its pleasant paid it causes them want to level the beta get higher the title Bay to get higher.
Michael Thonis: So the washers are actually a welcome event which is odd thing.
Mary Harris: hello, my name is Mary Harrison i'm a retired geologist.
Mary Harris: Have primarily focused primarily and sedimentary throughout my career.
Mary Harris: But I wanted to say that when I was.
Mary Harris: Getting my bachelor's degree, which certainly wasn't long time ago in the.
Mary Harris: late 1970s, I worked for bill cleary.
Mary Harris: As a student we went out and my husband sitting right here too, and he also worked up for cleary some, but we did core on the beach through the sediments kind of back behind the dunes.
Mary Harris: We were looking at overwatch, and so we saw the.
Mary Harris: You know the Marsh the sands.
Mary Harris: Oh yeah everything was in her bed, you know, but we did core down far enough.
Mary Harris: it's been a long time ago, you know you would penetrate through the market segments and, like, for example, the over washes from storm activity.
Mary Harris: You guys sea level rise, and then you have storm activity and that storm activity pushes the sand from the doing feel back into the Marsh and then.
Mary Harris: Because the sand was on top of the old marsh we could get access to the sent to the MARS.
Mary Harris: Because you're not in the martian around the sand flying and then we could core down through it and, like someone indicated there's a lot of compaction and you see pete and that kind of stuff but you're always running into more sand and and that can be from like.
Mary Harris: From intertidal channeling in the Marsh where the the channels migrate around quite a bit the MARS.
Mary Harris: Moves moves around quite a bit I mean we actually live on, because to South here on and.
Mary Harris: I can go down to my Doc and I can look at the water moving in and out of my creek and it's a roading.
Mary Harris: As you would expect, on the you know meander side of the creek and so that sand it's called up as the point bar.
Mary Harris: Moves is collected in that channel and it gets laid down, and so the Marsh is always alive with this movement of water from.
Mary Harris: The meandering of the channels and so so it's a combination of things it doesn't stay static as.
Mary Harris: As things work that the the channels migrate around in the Marsh and maybe you have a storm happen, and you might break open a new inlet through the barrier island system and things will get reordered again.
Mary Harris: And and and and it happens as sea level rises and one other thing I wanted to know was here, where we live on St Helena and South Carolina we get the the two to three meter tides as well.
Mary Harris: here.
Mary Harris: You know, we get some extreme dive yep.
Mary Harris: So just start to binge worthy I do that helped.
Scott Harris: And to add on to that, if you look at miles hayes's bercow the central South Carolina coast, a lot of his Grad students.
Scott Harris: They would drill down, maybe 10 meters and they're into the pre Holocene but that tends to be what we think of as the.
Scott Harris: You know the shore face the.
Scott Harris: I hate to use the word equilibrium profile, because we know that doesn't really exist sorry Robin to say that out.
Scott Harris: But, but so it doesn't really and if you go off of folly beach, for example.
Scott Harris: Bali beach here in South Carolina if you go off shore two miles and into 3020 to 30 feet of water, you have tertiary materials, excuse me.
Scott Harris: nia gene materials outcropping at the surface, so we have a very thin cover we're very sediment poor here, but then, if you go behind the islands, I can take you to places that as the other harris's we're bringing up.
Scott Harris: It that they're the intersection of multiple creeks and you literally get these scour pits that go down 8085 90 feet and they're isolated almost vertical and they have.
Scott Harris: Ancient you know paley i'm trying to use the new nomenclature, to me it was tertiary growing up, but the Nea gene materials.
Scott Harris: And, and so you have these holes that had been scoured out by the title current and so they're really good, and I know from some of the work we've done in some of the rivers on the savannah.
Scott Harris: The excuse me, the research vessel savannah that you know we see some of these as well, but these title creaks are the deepest carving things around.
Scott Harris: Much more than actually the shore face because there's a lot more constant energy in there is that is that, am I saying that correctly Robin.
Robin McLachlan: yeah absolutely and we see that down here as well, especially in the title creaks where you have a triple junction they get really deep you know 10s of meters deep skyrockets.
Scott Harris: I still want to go scuba diving in those but I.
Michael Thonis: will get eaten by something don't do it.
Scott Harris: it's called charcoal and it's where the.
Scott Harris: crazy thing i'm just more worried about life and cables and all the other things that would tie up in a in a noose and levy on the bottom.
Michael Thonis: But those those those those valleys that you're referring to those would be are they are they do, they bought him out, I mean they're probably filled with sand now, but would they have one time bottomed out lower than modern sea level.
Scott Harris: yeah um I mean I think you're not asking the question my yeah they're definitely below modern sea level.
Michael Thonis: Okay yeah.
Michael Thonis: But, but even filled in by sand.
Michael Thonis: As as it relates to the Holocene.
Scott Harris: sands and mugs and yeah.
Michael Thonis: So potentially a marsh can be going back to my original question and March could potentially reflect that that pre Holocene that bottom.
Michael Thonis: Right, I mean they don't.
Michael Thonis: I mean you have to those all those valleys you're going to get eventually filled, but in the policy.
Michael Thonis: And what they get filled with is either sand or.
Michael Thonis: If there's somehow protected by a barrier they're going to get filled with.
Michael Thonis: With pete I just so I me I just in a in a lot of this is just i'm just reflecting on my situation hearing that no one's ever actually fairly know ever drilled this the see how deep the scope.
Michael Thonis: They may only be three feet, the Marsh pete me over the three feet deep or it might be 300 feet I just don't know.
Scott Harris: I think up in your world i'm pretty sure some of the folks that woods hole have looked out there and they have I remember seeing a whole list seen ice Pack.
Scott Harris: In some of the marshes up there, I went to Delaware and I cannot remember, I mean that's been a long time ago, so I cannot remember any of the article.
Michael Thonis: i'll look for that.
Scott Harris: But the Delaware geological survey would be a great place to start as the usgs woods hole and some of the other groups up there.
Michael Thonis: Thanks.
Michael Thonis: I should just point out that i'm a trustee of the Museum of science in Boston, so this is a on doing this for them we're trying to do a better job with.
Michael Thonis: With New England, oddly there's not a lot about the earth sciences New England at that museum.
Michael Thonis: We have we have pieces of Mount denali but we don't have much about knowing what.
Scott Harris: i'm look for it i'll just get you started a Delaware geological survey look up kelvin ranting.
Michael Thonis: kelvin ramsey.
Scott Harris: Ramsay.
Michael Thonis: or a ramsey okay.
Scott Harris: And and he's a lot closer to there, and he probably has the literature in his mind for that far I.
Michael Thonis: Know i'll check out what's whole I hadn't thought of that.
Scott Harris: And so, Robin can ask another question.
Robin McLachlan: yeah absolutely.
Scott Harris: anybody else wants to jump in I don't want to monopolize but um.
Scott Harris: Are there is there any you know i've always loved the Georgia barrier islands, because there's nobody on them and i've spent a lot of time out at SAP below in the past, not doing geology visiting someone down there and just love the islands, but.
Scott Harris: Are there plans to develop are there has the political pressure risen so much that there are they are trying to put super hotels and condominiums out on these islands or what is their future From that standpoint, politically and then, of course, you know, naturally.
Scott Harris: How is that going to evolve.
Robin McLachlan: that's a really good question um I just moved here last July and the politics are so complicated that i'm still trying to wrap my head around it as well, but from what I can tell from other people who have been here a lot longer and seeing this political battle go on a lot longer.
Robin McLachlan: Many of the islands are privately owned and that's why they're not developed very so there as long as those people continue to own those islands there's not going to be any mega hotels.
Robin McLachlan: A lot of the islands, also have restrictions on how much land area can be developed, such as Jekyll island it's owned by the state, and they have.
Robin McLachlan: designated a certain amount of area that can be built on which we are very, very close to right now right so either we're going to have to move that goalpost once again or.
Robin McLachlan: we're not gonna be able to develop Jekyll much, much more, however, there has been a big push to continue to develop Georgia barrier islands, and as the population of the coastline is growing, the coastal zone is.
Robin McLachlan: outside of metropolitan Atlanta the fastest growing population in Georgia, and with that comes pressures to develop the barrier islands that are not yet developed.
Robin McLachlan: And so I know that there are battles currently going on there are battles, both for building permits, but also in terms of shoreline armoring and.
Robin McLachlan: Where we get to putting these hard structures on the coasts, so I know that those battles are happening, I know that a lot of goalposts are being moved.
Robin McLachlan: But just because of the private ownership of the islands and the state ownership of the islands it's going to happen slower here than it has other places.
Michael Thonis: yeah the problem with the speed ownership of these islands, and I know this from some of the other states down there is that.
Michael Thonis: The State stands to benefit ultimately.
Michael Thonis: From tax revenues from development so.
Michael Thonis: So it isn't as though they're entirely you know, on the side of environmental protection, necessarily.
Michael Thonis: And that's the tricky equation, you know what happened here on Cape cod is.
Michael Thonis: Under john Kennedy administration, the decision was made, I have, I don't recollect at all, how it happened, but it somehow decision was made to make all of this national seizure.
Michael Thonis: All of it and there were some houses, quite a few houses actually.
Michael Thonis: Practically on the beach or behind the barrier and.
Michael Thonis: And they were, and they were initially going to be all torn head to be all torn down and then there was a compromise made where they could continue to exist as separate houses.
Michael Thonis: But they couldn't be rebuilt, they fell down they couldn't be rebuilt, it could be, they could be maintained so difference, but they couldn't be rebuilt and that's been a huge factor and keeping the cake, you know from having just completely gone.
Michael Thonis: To a vacation land it's pretty much that anyhow, but not on, but not on the outer beach.
Mary Harris: So this is Mary I had a question.
Mary Harris: With talking about development is the issue of water, I salt water encroachment.
Mary Harris: yeah, we can only get out of the rivers so anyway yeah discuss a little little bit of that so where we live, we get water from the savannah room.
Mary Harris: So if you're up in charleston you get the water from the River of strain and so, then you know if you're down around brunswick, for example.
Mary Harris: In the probably get the water from the River maybe the order mahal river or something like that, so a lot of that, I think.
Mary Harris: is controlled by the water supply, because there really isn't a lot of water on the barrier islands that you can take advantage of it, and you know if you try to drill you know the deep whales and we'll just look at at of stuck.
Mary Harris: And we had a place in ESTA I don't know over 20 years ago but.
Mary Harris: You know, salt water encroachment there you had to go get in I had to go to the.
Mary Harris: The water plant, you know the water came to the House was sailing and you would float in.
Mary Harris: The water that you drink would come from a reverse osmosis system and you'd have to give your drinking water, so it limited everything in a big way yeah.
Robin McLachlan: I definitely haven't heard as much.
Robin McLachlan: As having issues here in Georgia as much as there has been in places like South Carolina and on so.
Robin McLachlan: Because there's not the barrier islands aren't hugely developed right there's not a lot of fresh water withdraw from those islands.
Robin McLachlan: Some of them like St simons and are very well developed so that might be an issue there, but I personally have not heard much talk about salt water intrusion and so i'm i'm assuming it's not much of an issue here, but I could be wrong, a little bit.
James Deemy: it's a little bit of an issue.
James Deemy: Around savannah it's probably the worst because a lot of savannah still get to their water at a deep wells.
James Deemy: A lot of the brunswick industries from the probably.
James Deemy: Through the 90s were a really heavy draw on the groundwater in this area and luckily.
James Deemy: In some from a groundwater perspective, luckily, a lot of those industries are no longer drawing right because they're not here anymore.
James Deemy: bad for the economy of the area really good for the groundwater right.
James Deemy: But all of brunswick drinking water does come from the upper floor and and that's that's that's our deep well in the area, so.
James Deemy: But yes, it could very well if you were to try and develop very heavily and say turn the Georgia coniston to Fort lauderdale and you've probably run out of water pretty damn quick so yeah.
Michael Thonis: Because I think, is it the case that the water forms a lens on top, the freshwater forms of lens on top of the salt water.
James Deemy: yeah but that's that's that's your like lawn irrigation water and that none of the residents on the islands really well i'll say on the developer islands.
James Deemy: that's not a drinking water source anymore that's that's actually hard county county regulation and they they get their water from the counties.
James Deemy: And then that's that's groundwater that they're taking.
James Deemy: You can irrigate from that surface water and most of brunswick itself is the same way, you can put an irrigation well on your property, but they really don't have people putting in deep wells anymore, where they can avoid it I eat where you can hook up to the county.
James Deemy: Does that does that kind of help with that.
Mary Harris: We have a situation here where you can actually install a lil but the water is so hard with iron.
Mary Harris: And it's all for us, you know from power right degradation that you don't really want it in your House now maybe if you were in 1950.
Mary Harris: That would be the case that we have like a county war supply now we have a well it's a kind of an interesting thing is down in the limestone here and it's down to about 80 feet, where the limestone is and.
Mary Harris: That water comes all the way up to within about three feet of the surface inside the casing.
Mary Harris: So it's under being recharged from somewhere that's pretty high elevation so I mean you know but we're in a sort of up undeveloped area on a sea island but.
Mary Harris: That we do have access to water, other than the county water, but the problem is like was indicated, if it was highly developed you deplete the water supply you're really quick what's you know, in the ground, the ground war.
James Deemy: yeah we could certainly we could certainly tap into those limestone geographers I mean it wouldn't you know and people have done that, on the islands, if you want to bring the equipment out to drill that far people have done that.
James Deemy: But it would become living pretty quick.
Michael Thonis: I was, I have a different question here in the field guide, I was struck by your some of your.
Michael Thonis: observations or or forecasts, I guess, about the impact of sea level rise, I remember one place, I think it says something about how.
Michael Thonis: You felt that marshes would see that here that Martians would be stable until based on you know mean predictions medium predictions are some predictions that.
Michael Thonis: That Mars marshes would be stable and I guess barriers would be stable through 2020 100 how controversial is that is that I mean is that his face i'm guessing that that's a very.
Michael Thonis: there's a very wide set of it, of forecasts around that media.
Robin McLachlan: There are, yes, and I don't think that that exact conclusion is very controversial, a lot of the the big coastal geologists here in Georgia.
Robin McLachlan: support that research and the research that paper said that because marshes already set so high up in the intertidal zone or the hindmarsh.
Robin McLachlan: That they can survive a certain amount of sea level rise and it's not until the year 2100 that in their models they found that a lot of land area of the marshes last or not, because the.
Robin McLachlan: that's when the Marsh has basically depleted it's area or elevation reserves, it would be no longer sitting in the hindmarsh at that time, assuming that median sea level rise up to the year 2100.
Robin McLachlan: And we've seen that elsewhere as as well, it seems like as long as the Marsh has enough time and enough area to migrate, and the Marsh will be able to.
Robin McLachlan: sustain itself up into a point.
Robin McLachlan: And this model using Georgia and as reference down at that point was around 2100.
Michael Thonis: So those that require the Marsh to gain elevation through the addition of surrounding sand.
Michael Thonis: or city or San from any source and or is that windblown or or just you know the erosion of headlands or does that or or is there a is there a contribution from the organic matter in the Marsh itself, like the p.
Robin McLachlan: yeah.
Robin McLachlan: Totally and the marshes are able to a great upwards, both due to the organic matter accumulation and by the root growth underneath the soil, but also by the the mud, and the other sediment that's being distributed through the Marsh with that title close.
Michael Thonis: yeah I had seen an article, and I think it was in the GSA maybe geology magazine back number years ago that.
Michael Thonis: Somebody speculating that it was a problem that which I thought was interesting that a problem that most town ordinances.
Michael Thonis: Were requiring.
Michael Thonis: That when a building is built, when a houses bill or whatever happens any kind of development that you have to put up a barrier to heat stamp from getting in the Marsh when, in fact, maybe the better thing to do, which is to say, and get in March.
Michael Thonis: which I struck me as an interesting and tricky tricky calculation right.
Michael Thonis: Getting that right or wrong, makes a big difference.
Michael Thonis: But that would be saying you know that would be the introduction sand from from rain or construction and then a rainstorm.
Robin McLachlan: And i'd be curious to know exactly.
Robin McLachlan: What they're trying to prevent there if it was just sand going into the Marsh marsh is a pretty good about being able to survive and grow up through sand deposits so even when we see these overwatch fans often the Marsh over time, will be able to grow up through those those sandeman.
Robin McLachlan: So I mean it does depend on how thick the sand deposit is also if it's from construction i'm guessing there would be other things other than sand.
Robin McLachlan: Right might also be why they want to limit that.
Robin McLachlan: At transmission.
Michael Thonis: I routinely go out once a week I go out into the Marsh here.
Michael Thonis: and
Michael Thonis: But today, as I mentioned we're having a super high tide so it's actually the waters above the grass grass still not really happening yet because it's winter.
Michael Thonis: But I routinely go there, each week and and fill an entire.
Michael Thonis: bucket filled with plastic that floats in and it's you know what the number one most common piece of plastic that I find every week is.
Michael Thonis: birthday balloons.
Michael Thonis: They get the march they stay on the surface right, and then the wind blows up against the shore.
Michael Thonis: it's charming, but still annoying.
Scott Harris: James you were talking a lot about the hydro stuff and I was curious, what is the.
Scott Harris: Do you have information on the rate of the land surface.
Scott Harris: lard elevation drops due to water with roll around savannah D is there a another.
James Deemy: The top my head, but but yeah we we did do that i'll hand yeah for sure.
Scott Harris: Because I just got a small grant for gotta have a couple of grants on using some of the insert data to.
Scott Harris: Basically, land displacement using some of the satellite data and so we're doing it in the charleston region, all the way down and we're probably going to be, you know dipping into yells part of the world.
Scott Harris: So you know if if you want to, we can talk offline about that, because you might be very interested so we're going to try to go basically from.
Scott Harris: The entire state of South Carolina But that does grab wilmington and savannah in the images and so I told the student, why not just not just clip it at the state border because politics doesn't have.
James Deemy: Well, I mean it'll be interesting to see how the water management on one side of the state border and on the other, contribute to that the that withdrawal subsides yeah and i'd be i'd be happy to even help you all work all the way down here in new brunswick you know, please, please.
James Deemy: get in touch with us, that was a great student project to help with.
Scott Harris: yeah Okay, and you know I might know Robin fairly well, so we work together a long time ago um so she's still young, though.
Scott Harris: And i'd have another question, and this is probably angie's question but angie's being quiet so i'm going to ask this question, do you see a lot of heavy heavy minerals, on your beaches.
Robin McLachlan: Oh yeah and i'll I can't give you an exact number for the substance right, especially in savannah, but I can give you an order of magnitude and.
Robin McLachlan: noah's estimated that there's been a 28 centimeter substance or 20 centimeter relative sea level rise so that's substance any static sea level rise so that's a good order of magnitude for the entire coast.
Scott Harris: Excellent Thank you.
Robin McLachlan: For.
Scott Harris: Go ahead and GE.
Anji Shah: na yes yesterday, for me, although you know one thing I wonder, since you have those subsistence rates have you looked at any relations between heavy mineral concentrations and and devotion rates I don't know that's sort of another level.
Robin McLachlan: I personally have not know James have you.
James Deemy: Seen oh that sounds great.
James Deemy: I should have bought her done something like that, like that, but yeah.
Scott Harris: Well, I could recommend angie for doing some neat heavy mineral type stuff and looking at.
Scott Harris: cool things i'll just say.
James Deemy: yeah we have an abundance of student Labor here, and you know we have a lot of undergraduates that are looking for projects to get involved with, so let us know what kinds of data, you need, and we can go collect it and help with that.
Scott Harris: Oh cool that would be that'd be fun to get our undergrads and your undergrads together.
James Deemy: Oh, certainly.
Scott Harris: That would be awesome.
Scott Harris: And so, Robin since you're new there, what kind of things are your fingers getting into obviously the barrier islands, but what specifics have y'all been doing.
Robin McLachlan: um well I haven't actually done any research here at least since i've been, but we are ramping that up we've submitted quite a few grant proposals.
Robin McLachlan: One of them would be trying to track erosion rates of the barrier islands, through a variety of ways.
Robin McLachlan: A big push on citizen science and having citizens taking pictures of the coastlines and then submitting those photos to social media we take those and.
Robin McLachlan: Through image analysis track erosion rates and inundation makes sense and things like that we're also trying to ramp up collaboration.
Robin McLachlan: With communities on the barrier islands we've been talking a lot to little Cumberland island Homeowners to set up citizen science projects as they're there as well, where we train them how to serve a beach transcends we train them.
Robin McLachlan: You know, to take to collect the data that they need, and then we and our students analyze that data and then give them a.
Robin McLachlan: Report that's actually usable right actionable data after that so moving forward my main goal is tracking erosion tracking inundation in a way that can be actually used by the communities down here.
Scott Harris: that's great Have you had pretty good Community involvement, it sounds like it seemed to have him on the hook.
Robin McLachlan: So far, yeah.
Scott Harris: it's awesome I look forward to see you.
Robin McLachlan: next few years, and now we see money.
Michael Thonis: Was be speaking of erosion.
Michael Thonis: inundation how different is the for low barrier islands that you're working and how different is the winter profile from the summer profile beach profile.
Robin McLachlan: that's an excellent question, I personally have not lived a full year here, so I have no first hand knowledge of the beach profiles, I have seen evidence.
Robin McLachlan: just looking at like peer walk overs and things like that, looking at the the elevation or the slope of the beach during this time of year and comparing it to what it looks like it used to be there definitely is a change and beach elevation profile.
Robin McLachlan: Right, where during the hurricane season it's flatter during the fair weather season, we get a larger Burma steeper profile, but I personally have not seen a difference with my own eyes James have you noticed those changes and profiles here.
James Deemy: i've noticed more of a difference with some of the sea island.
James Deemy: sand enrichment bleeding over to changes in the channels right next to St simons so sea island is part of the St simons island complex.
James Deemy: And when they enrich basically add sand to the sea island beaches.
James Deemy: That ends up changing the way some of our northern beaches on main the main St simons beach change, but no that's that's something i'll definitely be watching for now.
James Deemy: We got to have a student measuring that too, now that now that I think about that.
Michael Thonis: yeah or citizen science would work too for that.
James Deemy: And that's and that's been been the big driver behind these grant proposals that robin's been basically taking the lead on with citizen science aspect and we're really hoping to move forward with that.
Michael Thonis: Are your beaches are European of the GA beaches.
Michael Thonis: Probably mostly carbonate but i'm guessing this some courts mixed in, maybe, maybe not.
Robin McLachlan: yeah.
Michael Thonis: But it's mostly courts oh from the appalachians okay.
Michael Thonis: Oh interesting all right so.
James Deemy: All our carbonate stuff is down pretty deep.
Michael Thonis: yeah Okay, and you don't end in in terms of the service, you don't see it so maybe Florida.
James Deemy: yeah I mean you can you can find limestone outcroppings embedded in the coastal plain and places, and you can even find it.
James Deemy: You can find some some stuff closer to the coast, but, but the vast majority of the coastal plain sediments our courts and that's what gets washed down.
Michael Thonis: You know, eventually walk down okay.
Michael Thonis: I guess it makes sense given where you are you already it's Georgia, the appalachians are not that far away.
James Deemy: yeah well you know it's.
James Deemy: Yes, they're just there's been a lot of courts sands being deposited back and forth over the kind of still playing for very long time around here, you know where you know up in the paid mind that's that's where you get that really thin thin.
James Deemy: unconsolidated layer but down here on the coast, we have a couple hundred feet of sand so yeah.
Michael Thonis: Okay, I guess, I just thought, because you weren't your Florida might be more like Florida beaches.
Michael Thonis: I think Florida beaches are a mix of courts and.
Michael Thonis: In carbonate.
Scott Harris: The carbonates don't really become the major constituent until well below Cape canaveral I believe.
Scott Harris: Okay bill pretty darn sandy pretty darn courts rich in there.
Michael Thonis: Okay well that's good to know, thank you.
Scott Harris: there's actually a treatise on GEO morphology that has a section on the coastal barriers of the United States base or the east coast and around the Gulf, if you look up Randy mcbride MC br ID.
Scott Harris: And we're just we're updating this year so that was last night's endeavor.
Michael Thonis: No fresh on your mind.
Scott Harris: But it's a really good it has all the different sections that you'd be interested in and starts up in the north.
Scott Harris: That might be very helpful to what you're trying to do up there.
Michael Thonis: Okay, good thanks.
Scott Harris: So Robin and James what are your favorite parts of what you've been doing for this particular virtual field trip.
James Deemy: trip statler.
James Deemy: i've been teaching back and forth on SAP alone, since I was a graduate student at Georgia and.
James Deemy: You know if that that becomes pretty embedded in probably why I took the job here when I was when I was finishing up yeah I graduated one week and I was started down here the next and I haven't really looked back, since so.
Robin McLachlan: yeah I agree it's definitely the chance to not only go visit the islands, but in doing so, meet the experts on the islands which I would not have done so as such a personal level, if you know, I was staying in my office as I do, because of coding.
Michael Thonis: You know it's.
Scott Harris: it's very good, very good.
Michael Thonis: beaches are the safest place to be during coverage, you know, despite the despite the media coverage that shows people close to each other features are a pretty good place to be.
Michael Thonis: You don't have to stay in your House or office.
Robin McLachlan: Just a heads up we've been told that we've got a little less than 10 minutes left so if anybody's got burning questions now's the time to ask.
David's iPad (4): yeah hi this is Dave Ross usgs I don't know if you can hear me.
Robin McLachlan: I can, yes.
David's iPad (4): A lot of the topics we've been discussing here the usgs of course works on every day, I just want to make one comment about whole issue of water quality and brown water withdrawal, I know i'm now living in bluffton fast just started Hilton head neta to major issue here.
David's iPad (4): The drop down curve so much pumping on Hilton head island has now merged with a big drop down Cone in savannah area so that becoming one massive come.
David's iPad (4): And three or four, as you may know of the major municipal wells that were in the northern part of building that I had been shut down.
David's iPad (4): Now so they're having a drink more water in from further on shore and, of course, more from the savannah river area and they're having to move, of course, more to.
David's iPad (4): Reverse osmosis type techniques to provide more drinking water capacity and looking a bit more at.
David's iPad (4): storage and recovery, you know where we actually pump water down into old abandoned barriers that are now on sure, and then pump the water up as needed.
David's iPad (4): So, I guess, depending upon the population growth in some of the more desirous beach areas there could be continuing problems with water quality and water availability, as you do get.
David's iPad (4): The acting salt water intrusion caused by the overpumping.
Robin McLachlan: yeah thanks for sharing it's good to know it's I had no idea that Hilton head and savannas kind of depression was.
Robin McLachlan: And I did not realize that they were so large that they could actually.
David's iPad (4): now merged yeah.
Scott Harris: i'm David as we continue our work on the.
Scott Harris: lowered land levels, would you be somebody that we could contact.
David's iPad (4): That was absolutely.
Scott Harris: yeah okay.
David's iPad (4): I mean this whole sea level rise issues a major issue we're working on as many of you are.
David's iPad (4): And, of course, not just from the absolute see of arise related to glacial melanin and thermal expansion, but particularly modeling check with some of our colleagues that lehigh university oh issue of the.
David's iPad (4): Football collapse associated with a static adjustments from the glacial impacts, but also, you know from other studies that there's mantle fluid flow.
David's iPad (4): If a Cape hatteras hi there is causing uplift there and then there's a relative subsidence just south of that.
David's iPad (4): And then we're also looking at potential impacts and changes in the Gulf Stream, because you know there's a topographic effect to the ocean from the Gulf Stream and we're.
David's iPad (4): Even a paper that was out last week that you're showing that there could be a slowing down the stream.
David's iPad (4): And as as the temperatures change it could affect how the Gulf Stream behaves off the carolinas and Georgia.
David's iPad (4): F, it could affect water level as you get right to the coast, so all those factors somehow have to be integrated into a common analysis which isn't simple particularly it depends, where you are regionally, of course, for any of those issues.
Michael Thonis: I think that's great work it's you know the here in here in New England there's been relatively little sea level rise relative sea level rise because of the ongoing glacial rebound.
Michael Thonis: But you know there's no such thing as a free lunch, so the place that is getting the opposite effect is the Chesapeake Bay area.
David's iPad (4): Exactly I mean Chesapeake Bay is right in the middle of the area where there's a lot of ticket isostatic impacts, as well as absolute sea level rise and so.
You know.
David's iPad (4): The national wildlife refuges and little southern part of the Chesapeake Bay area.
David's iPad (4): are being impacted the US navy at Norfolk, which is a big ship Center there and, as you may know, is already.
David's iPad (4): Moving to raise their worse and Doc significantly, because the sea level rise there no one's waiting around in the city of Norfolk itself has a pretty robust program looking at particularly effective high tides and King tides on near coastal about buildings and streets and so forth.
Scott Harris: They had a Dutch dialogues are a similar similar to the Dutch dialogues, we had here in charleston.
David's iPad (4): mm hmm.
Really.
Michael Thonis: i'm not heard that expression Dutch dialogue, what is that.
Scott Harris: If you look up charleston Dutch dialogues it yeah basically looking at flooding in the future and architectural development around that.
Scott Harris: New Orleans Wagner and ball and then other groups, but they've done studies here in charleston and Newport news or Norfolk area and.
Scott Harris: We with a lot of help from the Dutch Embassy, the Dutch at the Dutch don't have a lot, but they know a lot about flooding.
David's iPad (4): yeah yeah I mean there's the.
David's iPad (4): The folks in Holland is that we have a significant collaborative effort underway with them in terms of modeling for all these types of processes.
David's iPad (4): Because they've had to deal with it for centuries.
yeah.
Michael Thonis: yeah it's Holland gleefully rebounding I wonder.
David's iPad (4): and
David's iPad (4): I don't know I don't know exactly.
Michael Thonis: Quite like a word that what yeah yeah i'll check that out.
Michael Thonis: Apparently, they have been it hasn't been enough.
Michael Thonis: Because they clearly have a flooding from.
Scott Harris: The Robin and James and the rest of you Thank you so much for pulling this together it's really nice to see this, and of course we're we're very proud of Robin because she's she came out of our college and so.
Scott Harris: we're very excited for what she's doing down there but y'all have done a great job and i'm really looking forward to going through some of the details of the of the Board there for our GIs it's.
David's iPad (4): Like, how do we get access to someone asked earlier, how do we get access to the guidebook.
Michael Thonis: hasn't been published, yet.
Robin McLachlan: The and the archie is story map that i've linked to at the top of the chat and you can also find it on the GSA schedule they're basically the exact same thing there's no information and format that's not also in the it's going to be in the published field guide.
Michael Thonis: And it's.
Michael Thonis: it's printable.
yep.
Robin McLachlan: When that field guide is published, I just got the the final version today so it's close to being published.
Robin McLachlan: i'll create a link at the top of the archdiocese story map to it, so if you're interested just check back in the next hopefully it'll go up.
Robin McLachlan: And also just reminder Scott, at the beginning, asked how I made those gifts of the satellite imagery and I also put a link up at the top of the chat to that as well.
Michael Thonis: Thank you.
James Deemy: Scott, a little feedback on your program you all did one hell of a job preparing preparing Robin for all this, she has been amazing.
Scott Harris: I would love to take credit for the College of charleston here, but I think she had some pretty good chops coming in, so.
Scott Harris: She was a great student to work with, and she already had her act together, we just helped guide or along she was she had her own engines, going so yeah but that's great news that's good to hear because she is awesome.
Michael Thonis: But you need to.
Michael Thonis: come up to Cape cod, let me know.
Scott Harris: Excellent.
Michael Thonis: Okay, good Thank you all right take care.
Robin McLachlan: i'm gonna jump it everybody again for joining.
RISE GSA Audrey Heun: i'm just gonna say thank you so much to Robin and James and damon and Kimberly were your other two field trip leaders on this from GSA and.
RISE GSA Audrey Heun: was really nice working with both of you, and this is a new adventure for GSA and trying to figure out how these online field trips are working and.
RISE GSA Audrey Heun: This is the fourth one we've done now for this meeting, and every single one's been a little different but really successful so.
RISE GSA Audrey Heun: Thank you for for all your hard work, putting it into the Ark GIs map storyboard map and.
RISE GSA Audrey Heun: really appreciate it and sounds like this was a great conversation, and hopefully everybody appreciated it and just wanted to reiterate that GSA really appreciates that you contribute and all your hard work, so thank you so much.
Michael Thonis: Thank you.
RISE GSA Audrey Heun: Take care of y'all have.
Robin McLachlan: A heck of a lot of work to throw together virtually.
RISE GSA Audrey Heun: All right, take care.
RISE GSA Audrey Heun: bye.
Mary Harris: Thank you bye bye.