Earth History of the National Capital Region – Volcanoes, Earthquakes & Dinosaurs… Oh My!

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Reston, Virginia, was founded 47 years ago & Europeans first settled in the National Capital region 403 years ago. This human footprint can't compare to the dynamic Earth history of this region, extending back as early as 1,180 million years ago and continuing today. For over 120 years, USGS has studied and mapped the region revealing a rich and diverse geologic past. Learn the story of the formation and destruction of continents and oceans, the eruption of ancient volcanoes, climatic and sea level changes, as well as the hazards of modern landslides, earthquakes, and karst. Discover the region's fossils, dinosaur tracks, and gold, perhaps in your own backyard! Bring your favorite local rocks, minerals, and fossils for identification after the talk.

Speaker: Scott Southworth

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Location Taken: US

Transcript

Earth History of the National Capital Region – Volcanoes, Earthquakes & Dinosaurs… Oh My!

 10:02

[Background noise]

David Russ: Well good evening and welcome to the USGS and thank you for coming tonight. I'm Dave Russ, I'm the regional executive for the northeast here at the USGS. And we'd like to welcome you to our evening lecture series, which showcases the work from the USGS scientists locally and around the world.

The science in action lecture series is intended to give you a better understanding of the science-faced issues that are meaningful in our daily lives. Tonight we're pleased to have with us Scott Southworth. Scott has been a research geologist for the USGS here in Reston for 31 years. He received degrees in geology from James Matheson University and from the University of Maryland.

Scott specializes in the broad but very important field Appalachian Regional Geology. It's regional because it addresses a wide range of topics including examining and booking of a number of different rock types. The manner in which the rocks are formed or deposited and later altered by burial and heating and mountain building processes.

 01:00

Randy has worked on several fields in geological mapping projects, developing significant expertise within the geological mapping community, and I might add with limestone and what they call carbonate petrology which is a type of rock that dissolves relatively easily, and we'll be hearing more about that tonight.

Randy's expertise led him to take the position of the Associate Program Coordinator with the National Cooperative Geologic Mapping Program in 2002 and has served as the liaison to the State Geological Surveys. You know there's a State Geological Survey in almost every one of our states across the country.

Randy has also served as Special Editor of the Geological Map of New Jersey, geologist for the Midcontinent Geological Mapping Project and Project Chief with the Karst Applied Research Studies through geologic mapping. Today, Randy has published 22 geologic maps and over 70 publications on a wide range of subjects related to Appalachian and Ozark Plateau geology.

 11:08

Scott has done an outstanding job at piecing seemingly obscured by the triple pieces of evidence out of the rock record to develop a geologic framework and history of the Appalachians. Tonight we'll hear about that history as we relate to the area around our national capital. Scott focuses much of his research on making geologic maps particularly of national parks for the National Park Service.

He recently completed maps of the Chesapeake in Ohio or C&O Canal, Great Falls Park, Great Smoky Mountains National Park and Shenandoah National Park. Ladies and gentlemen, it's my pleasure to introduce Scott, Scott Southworth and he'll speak to us tonight with the title of Earth History of the National Capital Regional - Volcanoes, Earthquakes and Dinosaurs... Oh my!

[Applause]

   12:03

[Applause]

Scott Southworth:  It's a pleasure to talk to you tonight. Thank you all for coming. I wanted to first thank my wife, Donna, who has always geared me up. And let's turn on the mic. Let's first, I've got a lot to talk about tonight so let's get started. But first I'm going to clarify that wasn't the trail of my talk. I'm really a dirt bag rock geologist but I am going to try to impress the earthquakes, volcanoes and dinosaurs for you.

The real plan of this talk is the geology in your backyard. We're going to get to this but I'm going to set you up in a larger framework for you. Get to it. We have a lot to talk about tonight and we're going to talk about the G in USGS, which is geology. The talk is scheduled for 45 minutes, that's 280,000 years of myth that we're going to cover so I can guarantee you I'm going to run all of them so if you have questions, send me an email please.

 13:09

So tonight I'm going to address several themes I want you to take home and think about and I think it'll broaden your perspective. So the first is top. The second is the fact that the earth's history is recorded in the rocks. It's very difficult to take horizontal rods turn them all in before these were even possible so that your imagination is in. The last is, it is a world of shifting plate, tectonic plates and landscape changing with, and to crib something that in severance over years ago. In this context the mountains and oceans have of stringents collapsed and I think you don't get that impression as we do the talk tonight. So the context of this broad beat time, I want you understand that native Americans were living here at least 16,000 years ago

 14:09

The first European to settle the area 403 years ago and this is what the landscape looked like if you are to see it in space. Every nation has celebrated this sordid 35th birthday. USGS to 132 years young and has spent 120 years of research on rocks in this area. So this is not my story but the story of many, many people and I'm going to point out two of them tonight that started it all, Arthur Keith and Nelson Dark.

So let's start with the level to Virginia in context the times and for the note that it was not here 47 years ago. This is a point where there on this area for source, there is a location. You're going to see that throughout the talk so you give breath if you know what you're assisting with.

 15:08

So John McPhee described the rock this seem a great rock.

Dave Russ:  Yeah.

Scott Southworth:  That's right. Let me help you see it but it the broad geologic term referred to is deep time. And you could see here is the geologic time scale, the oldest rocks that we'll be talking about are 1.2 billion years old. The rocks get younger and end up to the modern times and for scale, I want to show you that this box represents 10,000 years. Now in order to scale that for specifically the youngsters in the crowd we are going to take that geologic time scale of 4.5 billion year of first history with scale to a soccer field and for the National Capital Region, we're going to be talking about things that happened over 1.2 billion years which placed in 30 yards.

 16:13

There's a related turf from that field. It represents 10,000 years which is when the edge of agriculture came to Native Americans. So for an introduction from, as of today, I am a project commander of the Appalachian Blue Ridge Project which is housed in the eastern geology and paleoclimate center. That is part of the National Cooperative Geologic Mapping Program that falls under the core of science systems in terms of their organization. You know, how do we the geologic mapping? We're blessed with a nice agency that equips us with some very good equipment.

 17:01

We drive around the streets, communicating with satellites through control mode and it plots up the geology for us. Thanks for that because we, we don't know how to do that.

[Laughter]

You cannot see the rocks because of everything else here. So like I said I'm going to turn to that geologist, boots on the ground with virtual tech, ammeters, compass, altimeters, endless topo maps and you have Seal Rocks to understand.

So tonight I'm going to talk about the National Capital Region where part of the Appalachian chain we're in this called the central Appalachians and I want to set a context because I cannot make a geological map without a face map.

 18:02

So USGS makes the best maps in the world. These topographic face maps are digitized to create what's known as a digital foundation model or image in this case is portrayed as a tilt shade so it looks like you're looking at a set of solid fair ground. Throughout the talk I'm going to be using that color coded version of that. It's color coded by altitude. So the high elevations are light colored down to the green below, at sea level.

OK, what we do is we actually make what are called 144,000 scale, 7-1/2 minute geologic maps. That colors that you see all over lane two different types of rock, different ages of rock. These are used to the file what is known as the 100,000 scale map. There are 32 of these. I've never, just so you know, one of those is 35 square miles. So instead of, that'd boost the morale.

 19:09

That would be reaching the nose of two of tile, in this case showing three maps that then goes into part of geologic map of Virginia, called this in 1993 that then goes into geologic map of United States and eventually North America and of course this geologic map of the world where it leads solar system up the notch.

OK. First of all you set a context to the variety of rocks that are in this region, I want you to understand that the earth really is truly a rock machine and this is due to plate tectonics. A hundred years ago, Alfred Wegener came up with the concept plate tectonic theory and I think all the students that are at schools today are starting to see that the tectonics do pick together light plates and the rocks that we'll talk about tonight show you that air position is not going to be in place over time.

 20:20

These are 100 plates through the geologic record. We'll be talking about the creation of Pangaea at the end of what's known as the Alleghenian orogeny 257 million years ago. In the other vision we'll be talking about rocks of that age when this part of America was underwater. And we all again lie very close to the southern pole in a super continent known as Rodinia and all the rocks moving southeast might hit the steam. So this rock machine relates to a rock cycle. You probably all learned  the three types rock.

 21:02

And we have all of them expressed in this part of the world. There are sedimentary rocks that are buried, in the heat and pressure become metamorphic rocks. There further in the mountain some igneous rocks. At the surface of the earth there are weathered the beaten parts of sedimentary rocks again and the cycle continues.

SSo how do we study these rocks? Well after we wear the boots and map the distribution of the land, we go collect samples. We bring the samples back and with a saw and grinder you can cut thin slices that rock there was a thin section you can look at it under the microscope and it's a beautiful color of minerals that you see in the photomicrograph that allows us to determine what could the minerals are what the rock type is. Then the fun part comes. We get these nice uniforms, then we take off the shackles and we make little ones out of the big ones.

 22:07

Then we use some really high tech pack of jeep in the field and then the fun start. We go in and crush some rocks, they separate we can easily detect the minerals. They picked and mount the minerals to be analyzed in the space observed on and then we could term the age based on the radioactive contained in the radium lead in the sophisticated machinery relay the mineral part of Australia or Canada. Most importantly, we employ only the best and we had the best work before us so they could share their line of thought.

I give one example of work he's done before around Shenandoah National Park where the oldest rock that we have showed here as in seal within a younger bracket that serves on from this rock it's crystallization age is 1183 and these rings you see on the outer edge are more than millions of metamorphic polar probes that formed as this bracket was basically consuming this.

 23:20

Now all rocks are igneous. Many other rocks in this area are sedimentary. Here's an example of one classic one near Chain Bridge Road, then right before General Adkoff worked on. And this is a new field of geology which is exciting because rocks like this are metamorphic. They lack fossils so unless we have cross studied igneous relationship we don't know how old they are. And so to gain now is to extract what are zircons eroded from the igneous rock that were found hidden in the sedimentary rock. If I hold that statistics you keep them up with minimum and maximum age.

 24:04

We also use carbon technique to determine the age and conditions of metamorphism my compass and lab here in Reston analyzed muscovite, biotite, micas and antromole. Champion engineers who are sitting there at the back, they count fission tracks when their eyes are level and this determines the time of collective cooling plates and all these techniques, they go to a super computer brain, and would take it five minutes who by combining the birthdays and when these rocks converge at a similar temperature tell us when and in what conditions they converge or come together in fossils. So in addition to the earth being a rock machine, it is also very much a surficial machine.

25:05

Color codes have to be preferred in glaciers as a dirt machine and they truly are. They only use dirt. The erosion of glacier produces rock and debris that gets a positive, that is a future groundwater aquifer] and as you know rivers are kins. So much of the various study in the rocks of this region are based on the outstanding soldiers about to jump in the river. Locally good examples of what are surficial deposits for those who lived just West of here in Sterling, behind Costco are river tears deposits that are five kilometers from the present Potomac at 67 meters above the current base above of these quite ancient names. As you get closer to the river, you can see boulders that more than likely had to be deposited drop with the help of axe.

 26:09

OK. Now to set the stage of what to show you your position in the physiographic province of this region and why it matter. But first you should understand that the different physiographic provinces are defined because they're generally different rock types, the different ages of rock, the structure of the rocks are different and surficial processes affected them quit differently. So it sets up a pretty unique are on this part of the world.

Why they matter is because why they're not is the rock's promised some landscapes that drop ecology. If you want to get anything in all of this I highly recommend you get to the Natural Heritage site in the State of Virginia. Gary Fleming has done a great job you all have to see this.

 27:00

So we're going to start off with the Piedmont Uplands because resins sample. I'm going to go through here now to show you some, somewhat dramatic scenes to show you that they are different as we march across the provinces. Great Falls is probably the best example of Piedmont Upland area it's in the size and erodes to Shingle Mountain, here in Maryland are some of the other examples.

In contrast, within the Piedmont is what's called the Piedmont Lowlands. In this case there's a sort of called pair of basin and it's typified by extremely flat land that's why we build their hooks when we do. To the east of the Piedmont is a coastal plain, there is a boundary. It is on the name by Unconsolidated Marine and Terrestrial deposits and of course typified by your beach coast.

 28:04

To the west of the Piedmont is my Blue Ridge. You probably saw the Old Rag Mountain, Shenandoah National Park, piece of Otter, Mount Rogers including samples of that landscape. West of there is Madeline Ridge typified by Shenandoah Valley which have deposits from valley here west of there Windsor Valley and there's the proper showed by Germany Valley and classically the side of the hills in front Maryland which by the way is showing the first beds of coal in the Zurich reference. And lastly west of the valley and ridge is the plateau province. We're all at high innovation really defined by the flatline rocks but it's also where all of the gas industry and coal is extracted.

 29:01

So they're all quite different. Now back to the dynamic extract for the region, but I want you to, come on why do we have these provinces are not set in time. They shattered, they changed and the rocks have not always been where they are now and they will not last here forever. As the road, I mean look at, I'll give you some examples of what this means. When we make a geological map, we measure the structure of the rock on the field that is chosen to produce in the geologic cross section. A one way to envision what this means would be to get a super bulldozer and cut a four-kilometer deep trench across the Piedmont to the Great Valley and this is in way of rocks as you see. You could see the colors of the rocks and their structure will have to or different everywhere and there's a reason for that.

 21:14Some springs land to the side of the mountainsides. Here's a cliff. It's a very large cliff here at a big dolomite rock ledge here in the cave system in Missouri. This is probably the largest sinkhole conduit spring in the entire U.S. This is all called, believe it or not, Big Spring. It's amazing what the name is, right? 

This produces 279 million gallons of water a day on average. That's 13 cubic meters a second, 13 meters cubed, a second. This is just basically an instant river as it explodes out of the ground. And you can see here, from this vantage point, you can see how this forms out of the ground.

 30:06

The simplest way to explaining this is that you crinkle all the lug and you straighten it out. So in this case, we would take the cross section of the area and we resort, we pull it back to where it began why prior to faults tectonic digging. In a simple fashion what I'm trying to point out here is pretty interesting that the people who lived west of Lavelle County, they're real say originated beneath perfect sounding every fault everyday. Likewise we were sitting here addressing, originated just beneath this big bed. So all these things have changed in time and will continue to change. And here's another example. Here's the coastal plain Piedmont boundary. You can see a staggering of deposits that are west of that line and I've been drawing your attention to this one right here because of some, you probably driven by it more than once and didn't want to be drowned by it.

 31:16

This is the 495 Beltway ending in Tyson's Corner. I'm going to show you now a cut that I was able to see late at night and worse I think 495 mile along the road and the Beltway and Tyson's Corner are built on the former coasts' way. These are patches, there are some heavy marine deposits in the ground at the base and that one location is about here and the concept here that when we get across is worth by, I'm actually in referenced to you guys interest and I'll cut off from here but not mixing in others and rock means Lucy Edwards' work has shown that 13 to 12 million years ago, the coastal plain extended likely as far west as the Blue Ridge which means that the next time you travel I-95 to the other fence, in vision about 200 feet of work over your head.

 32:21

You know you don't need that concept here along the local tone of river are some of those hot and sea floor deposits. This is in part why I became a geologist is I used to find my sea fossils on the shoreline thinking they were coming from sharks floating in the river. This is the ancient sea floor that's been up there. So this line boundary will migrate as the sea levels rise the lands rise and fall.

Finally, we're going to go head the geology you've got there. OK. We of course start, get your locations here, you will think that, I don't know how they planned the site here but it kind of an interesting me.

 33:05

The National Center is built right on contact between the Piedmont Upland the Piedmont Lowland. We've actually got a fault that runs through the National Center which is kind of interesting. And we'll start first with the Piedmont Upland. All the rocks on this side of Reston are called the metamorph formation. They got metamorphs somewhere near Great Falls. The units are comprised largely of that of Great Valley very well observed in Great Falls very poorly observed in Reston. The other kind of rock we find was a beautiful muscovite garnet pair of schist that used to be the shale. That gray rock that used to be on our coast. They've both been mineral folds with very high appraised so they're a little quite different.

 34:01

In addition what you probably all see a lot of is metamorphic quartz. Now to stretch your imagination we're still working on the age of those rocks and right now we can put our finger on, they were positive after 600 million years ago and before metamorphism about 490 million years ago. But where they originally were positive where in deep channels is turbeducts. That image you Google image here called the west coast and from California and endless Laurel Canyon cuts out goes to Monterey is good analog of where and how the loss of metamorphs is possible.

We move west of the Upland, we enter the Lowland of the Culpepper Basin and in this case we're going to begin with the basal unit is actually named after Reston. It's conglomerate that is exposed or was exposed along the WNOD bike trail. The green unit is the fool's gold member, red shale and sandstone again not well exposed.

 35:17

Another big player in the sand construction industry is dikes. This is an igneous rock that was intruded into these older units and this is quite hard and when it intruded, the red shales and created a metamorphic rock known as hornfeld; it's about contact metamorphism. For those that recognize that this is the toll booth the Bellmont Ridge at the Belt's access road. OK. So everyone here has a name and some of what we do is we give and name some things that we saw just to little keep it straight and the geologic names are named after what we call typhoon county or typed section.

 36:09

So I will give this quickly. This is not comprehensive but just to show you there's a lot of rocks in this area that bear little names. Reston Manassas, Churchwood, Kensington and Old Rag. And then we have formations metagorges and topping. It's just it matter we know that we have appointed the names. So through here I'm going to show you some examples of what I consider to be a little rock salt. One example is the Falls Church intrusive sweep almost 470 million years old, used in a lot of structures around Falls Church. The Georgetown intrusive sweep two million years older very distinctive, dark igneous rock and you might recognize this in a nice monument. The upper majority of that being in Catonsville Marlboro, Catonsville, Maryland.

 37:08

Another great player is the face of stone for White House is the 60 million year-old the quiet sandstone down there. The Smithsonian castle constructed with the fool's gold member of that sandstone and another great local art he's the board member of Manassas Sandstone which is a conglomerate and Benjamin Latreau picked this out they were polish and form the columns of Century Hall, US Capitol.

OK. So this, mostly a snapshot of the rocks. I wanted to talk a little bit about what happened in the Pleistocene that relates in part to changing climates and different surficial policies and I think it's an interesting thing that 18,000 years ago, less than 150 miles north of here was a mile thick sheet of ice that covered a large part over there.

 38:21

We've only suspected, we know from Ohio because we have good evidence they were but those of us who worked the area and we've always had feeling this area reflected a permafrost conditions in landscape accordingly. And we're now starting to see evidence for that in which I'll get to. One of the by-products of the Pleistocene climates are some of the fluvial immersive features that we'll along Potomac River. I'm going to give you two examples around Great Falls. The first one was the area of Great Falls Park in Virginia showed good evidence of a Potomac River as it migrated across the bedrock cut down and left a lot of bedrock tears.

 39:14

A recent study done by the University of Vermont using constant injecting beryllium pertaining analysis of quartz grains in the many great lab may determine that the Great Falls and Mather Gorge were as such between 35,000 to 30,000 years ago likely driven by increase of precipitation at the end of Wisconsin Glaciation. So many people who've passed have seen the big rail holders of diabase around the Reston in the further isolation of rocks. The glaciers warm up here, those are not glacial rocks but the effects of the glaciation we could see ends up.

 40:03

Jeffrey provides that really good shot of some of these features preserved due to the stand on cutting. Here's a 16-foot canoe with two minimum scale and there's 6-foot something Jeffrey will be down one of them. There's a huge potholes to this incredible erosion forces. If you look at Bear Island this is a color coded DBM hike the building go to trail you would go in and out channels, potholes and staying over islands of the fork riverbed prior to cutting down these current channel.

If you really must see a sanding example this is the reformation village then you could see the bedrock and the river on either side and this deep dark colored stretch of water. Jeffrey used the front line of the canoe to map channels in this part of the river.

 41:08

And for scale, I want you to know, I'd love to do that there. The scale, there's the USGS National Center. It's 105-feet tall seven floors. So we can take four of these and drop them in the surfs of Potomac River and you won't see the dolphin. These are huge relative features that would be understood today. Now to the left of Reston in the Blue Ridge and Valley Ridge Ohio, people have known and suspected for years at that altitude we indeed had fair glacial features and you could see in the video today in the form of rock filled the streets closed. These are pretty much fossils. They're not actively forming today. Let's go back to the change in climate.

 42:06

And we have a group of people in our team that's having a lot of fun now with the live data that produces imagery in areas below these. This is along Potomac River and these should come from the coastal plain of Maryland from the east side of the Potomac River then the southernmost on the Delmarva Peninsula where these are Aeolian sing to do it for this relating again to winds during the Pleistocene and this green floating ephemeral basins, Caroline Bay-type features that are definitely related to a periglacial quad.

OK. Now I'm going to step outside in my realm just to educate you a little bit about the G in USGS. And I'm using the websites so maybe you can feel more comfortable with it. One of our big programs are natural hazards and I'm going to address, landslides, earthquakes and volcanoes without a warning, we don't really have that many hazards here, that is what we'll talk about.

 43:20

In terms of landslide hazards, they're all storm-related and storm-driven. With that thaw at the bottom is the first one that I've experience in my lifetime was in 1969. Hurricane Camille affected Nelson County, Virginia. The post documented event occurred in 1995 in Madison's County and it wrecked havoc. Fortunately, very few lives were lost. But these are rare events, '69 and 1995 but the, it's an inactive process. Now earthquake has, this is 1750 to 1996 compilation of all the major earthquakes in the United States.

44:09

From there the seismologist had come up with a map showing you the intensity or the hazard affiliated with each year. First and foremost understand that we're on this notice of trailing the edge for passive margin. So we do not experience what you know on the old stoke. This is a live active program. If you'll look this is taken down today showing you that we had nine and a-half meter 1736 but we have talked a little less than the days here but this is today in California. We have been funded to navigate all signs of activity where you expect it.

So this little cave down here when I was here in Woodstock. You can see some type of screen, and that's what you get in some cases. Other cases, you get this more framework type of passages. But what we're trying to do is understand what the controls are on these cave systems.

We're coming up on our one year anniversary however of the magnitude 3.6 that the history says it was the first one we've ever felt.

 45:09

Did any of you feel it? Well it's a, kind of, it was an interesting thing. It's, what I want to point out to you is the press was in the parking lot as you would expect. They wanted to know what caused it. I want to point out to you read the detail, keep in mind that for starters the depth of these things are five kilometers down. So we need one of the bulldozers to really understand what caused it. More importantly, however, is the locational of 13 kilometers.

It's kind of hard for me to explain to you tonight when it caused something like that when I felt that at the location. So knock knock into us it's part of mother earth I was happy to figure how to study. These are one, two, three different paths and there's calculated by three meter of entities.

 46:10

So USGS have to fall on fault that I had mapped which others would tell you had nothing to do with the earthquake. It gets a poor concept. OK. Well they don't have, we have ancient volcanoes and ancient volcano erupts. And the are pretty amazing examples of them and I want you to keep in mind that ours are significantly older and very much smaller than the modern analogs that are.2 on the western United States. And best one by far, which is I think a true volcano, is Mount Rogers in Southwest Virginia and volcano eruption associated with the fault of mountain lodges rocks formation which is contained in a 756-year-old result.

 47:06

A roughly analogued to it would be Yellowstone Caldera area. It's younger than 17 million years old. It's quite active but it terms of scale, I think Mount Old Rag is above the scale. So not fair in comparison. The volcanic rocks of Shenandoah National Park were mostly basalt mainly 565 and a , it's a felsic layer associated with them and like Yellowstone these roughly have origin that are similar to the Snake River plains of Idaho into less than 17 million years old and the scale-wise Shenandoah's about this big in comparison to that at that time.

So we have good examples of the small. One of the right ones I worked on is the Chopawamsic Formation 453 million years old it was an iron rock and I'll give you an example of what that is and what it looked like, their evolutions of the last time there was 4611 years old.

 48:14

And lastly not all the igneous rocks are volcanoes. There is intrusions and extrusions. The extrusions were volcanoes. The intrusions of where the igneous rock intrudes the sedimentary from that orbit rock. We got two examples here one 48 million years old sits out in Harrisonburg, Virginia and Great Valley and this analog is a 50 million year old basalt. These formed an identical scenarios. The igneous rock intrusion, the basalt rock, basalt rock from it. So today what looks like a streak of volcano is just a resistant ribs effect in its system.

 49:03

OK. This is one of the, if you read my "Oh My" title. I decided to get some young paleontologist interested. So I'm running through where you can find the fossils of you interest is. Many, many folks look for west of the Blue Ridge are the families of the rocks of the Falcon Ridge and John Repetski and Danny Brezinski at C&O Canal for a good job of showing the halings or index fossils. They are type two deformations and this is the way to teach you the purchase of maps and then we should go find it. It's a good example of... In the Mesozoic basin which Reston is now a part of, Rod Weeves had studied the Canapis minor footprints taken from the foreign Culpepper and there are a bunch of fossils of fish.

 50:06

Where you could see fish scales and fins preserved in black shale that's more in the lake bed. And the younger part of the record Cenozoic, we have Dinosaur Park in all of Maryland and Peter Grandsen tell you everything there is about. I want to highlight both the nine-year-old and seven-year-old may lose from finding the park workup in there. So they were bound to be found but as I've told you before, Sara got my interesting geology counterflips and the horse side flips, abundance of my C&A fossils mostly marine but also camel feet, so on. OK lastly I'm going to give a quote from my friends in the mineral resources program.

 51:00

And the first I was, received yesterday that they are playing zip it. They don't want to showcase way up the door here. So this is marketing for them and Eastern Mineral and Environmental Resource Science Center. What they'll do is that they'll collect some rocks and minerals in Fairfax County keyed to a map and this example they sent me is a pretty more piece of trimmer lining asbestos that was taken from the pretty ridge complex near Fair Oaks that they have taken a few years ago.

Now they also did a nice job to fly to me for those who are unaware over this, there is an incredible history mining in Syria most of it is historical. Some very important aspects of it is occurring. I will highlight just a couple of those. For starters for those who live in the Reston during the Cold War, you've probably driven down the Copper Mountain Brook that there was indeed a copper mine out of the basin rocks along that brook that so long exist.

 52:15

The two of them are highly today though occur out here near the airport and over here near some creek. This one is extremely important. Here is around 50 that was the airport. You probably driven by this and not even know it. It's a beautiful hole in the ground to extract 200 million-year-old diabase that is extremely important aggregate for what's going on then National Capital Region as well as roads but most importantly is this one. I just found out today it's 1528 an ounce of climbing. The area of Great Falls actually C&O Canal National Park in Maryland is an abandoned gold mine.

 53:08

This is a piece of gold in the quartz taken from that mine and people actively paying gold trips there into the river to travel. So with that, I'm ready for you questions and I will advertise the next part.

[Applause]

Yes? Can we get the lights on?

Speaker 1:  OK. I'm sorry but I hear your theories in earthquake in all the city. If I back to in, it's very Cleveland and I thought I have left the washing machine on and it wasn't, this is 5.4 magnitude earthquake. So my question is, sometimes you read about it there are another parts of the world that are saying intensity 5.4 and they do so much more damage than they did for Iowa, there was no damage and I'd like to understand why that is.

 54:25

Scott Southworth:  My, this is not my field but my guess would be if you have a 5.4 in an area with buildings were made of working mud in countries but not as built as strong. Yes?

Speaker 2:  I can answer the question.

Scott Southworth:  OK. Answer the question.

Speaker 2:  The answer is set to the same slogan of yours and, for example any work that you have built prior to some here, you go to 80 and the same magnitude. If it's very close to the surface and also what kind of rocks are there?

 55:06

You were seeing every basin where the rock, where soil puts the metal at some for support of the buildings. Mexico City could be advanced other example.. in San Francisco, there's another time for that.

Speaker 3:  Will these igneous rocks, I mean, the biology some... reason how the set appear with the oldest rock down the canyon?

Scott Southworth:  Thank you. We're working on that. The oldest rock that is like 4.5, I think in Australia.

Speaker 3:  4.5?

Scott Southworth:  Yeah. It was like 4.5 billion. In this area, the oldest rock is about 1.25 billion.

 56:11

This one would be like before what John Lenic call the dominant fault. There's what's called the Baltimore gneiss. The ones that we have closest to here the oldest is 1.18 billion and it's from Madison County near Shenandoah National Park. The old rocks which I sure have pointed out occur, let us see if I can grab to show. They occurred lunar it is why I worked with it. They formed a core of what's called the Bloomridge Septine from Oregon and the core of that as rock's center 1.18 down to about 900 million years old.

 57:00

I'm going to further answer your question as we're currently working on this problem. There's a rock in Tennessee on Roan Mountain, a very beautiful place that isn't published consistently for the last five to six years as being 1.8 billion years old. They can get the oldest rock in Eastern North America. We have been studying that rock and it contains the tribe of zircons that is that old. The rock is actually only 800 million years old.

So if you look at the geological map of North America, we have lots in the east that have lots of similarities in the western US but for errors we're actively working on to define that scale. Sure, make sure of, there will be, that was...

 58:07

General's Tower, it's 50 and Mobile Hill is 20 so that it was softer and that was to be both lay, it led to be making it mostly... It's the same type which measured 100 discs. Here, there is another, in this case, the sediment covered, if this is true there were soft made from shale that moved away pretty quickly and in that way, these are very complex and folded mostly with carbonated rock limestone, gold mine. This things shot right through there but what happens to the calcium carbonate enriched rocks is they dissolve and that's why they formed caves and seabeds. So if this sand have, I don't know I can point at 100 discs because that that would... This is a flood that will shot the mantle?

 59:01

This is a flood, which shot this. The point I'm making is it is truly devised that sits the dissolved away, eroded away they leave a landform that looks like a volcano. People keeping furnaces say this was a volcano. I always though this was a volcano.

Speaker 4:  What kind of access are you going to find when you got access and other construction...? When they are used today are you putting out what we have heard about making those buildings and you all have the, a similar...?

Scott Southworth:  It would be nice to but the reality is that I have a job to do and not a lot, as in driving home but not allowed to.

 1:00:02

I'm driving without the pay and I'm like, man I'm going to go back and look at that but I kind of know that I'm not allowed to do so, so they'll work on the job. So I told them I did not.

Speaker 5:  You know if you're not the...

 1:00:17

Scott Southworth:  It also has a lot, one of the issues they don't want you on the construction site and if that was a freeway that what had you. The hornfelds, they listed private companies. They were very helpful and let us on to it before opening that road officially. The bus stop at the Interstate 66 today, it stayed true for long not when your feet will get off. So it's not that easy. Oh, and this is a golden opportunity I knew of, my friends and colleagues here tell me, get out there man. I drove out again last night, it'll be gone soon. Those pictures I showed you in Iowa, it's the long something.

Speaker 6:  I have read on the River Valley... but it was there. It's a river valley area included and you knew that, I meant that you know about?

 1:01:12

Scott Southworth:  You are going to the eastern edge of the one which is called Culpepper Basin.

Speaker 7:  According to that how wide is that river?

Scott Southworth:  Well I will see if I can grab it and show you a thinning gravel off in this schist but sooner than later they would pit and go the right direction. In short, it goes along the shores of Virginia to actually, there's a gap of Frederick Miron, but the reality, it can support the newer basins it was only New Jersey and then it jumps up to infinite, somewhere that you have fun. It's equal to questioning oneself.

 1:02:06

It is from here to eastern Ohio. Thank you.

Speaker 7:  Did you hear that? It's called...

Scott Southworth:  It's ah, there actually, I use another beautiful way that at the tricolor would glow and people thought it was mostly brass, copper, blue but it's actually rose, black and yellow. So their very colorful codes, you know it's that.

Speaker 8:  Hey listen, I just though of this four and a-half years ago and we were talking about rocks that, there is eight younger then so, what do you mean by rocks 18 million years old?

 1:03:15

Scott Southworth:  It is a super phony addressed question. Now for Culpepper Basin if you're right here in the edge of it, it goes up to Leeseberg north, there's a teeny gap that add deformity to the front of it but in reality that was all meeting down towards General's Field and the east margin just said so. So it's condition-wise I don't have to seal its fate. Now for you to go back to the rocks, I wish there was a quicker way to do this stuff. We are constantly creating rocks.

 1:04:02

They are formed today as material with some has found, Potomac River into the Chesapeake Bay out into the Atlantic offshore just being buried and more or less it's buried or seven digits buried they were probably never dead. The burying spots that's part of this rock machine that may involved plate tectonics where it's constantly making lofts and this is what I was just talking about. This material is going into the continental shelf from the Eastern US it will become loft. If we are lucky enough to get a reversal and erectly tectonic seven, you send them down to subduction zone they get them water poles and melted and they pop up against volcanoes. So you get this process going on since 4.5 billion right here.

 1:05:08

Speaker 9:  How long this will be by...?

Scott Southworth:  We, they didn't know Greg and Alma granted as part of their study at Shenandoah. It is one billion 16 million years old. It's a pretty discreet grand that underlies Old Rag with a couple of dikes to fill out the rim but it's the rim by block setters as old as 1.18 so 120 billion years older and rock center about 40 million years younger. So it's just one series of grand intrusions in that part of the world.

Speaker 9:  All right. Thank you.

Scott Southworth:  Yes?

Speaker 10:  Are there dinosaurs in there?

Scott Southworth:  Yes. This here right here is the expert on. There's Dinosaur Park in Laurel, Maryland. If you go home and run your computer, you could go there yourself to look for it.

 1:06:11

Yes?

Speaker 11:  Does anyone have any goal or tell us everything for the technical and things like that? So we will see how, if something is down there.

Scott Southworth:  Yes.

Speaker 11:  That's too bad?

Scott Southworth:  Yeah it is. Well I can only be at one place at a time and we, we sort of all sent, you know, you almost lead someone dedicated to active construction sites. Because if they're here today gone tomorrow and...

Speaker 11:  Would it be for bits of profit?

Scott Southworth:  In fact my important sea schindler I've got both loads of data prompt and metro project. And I could probably but I got other things to do, get permission to go on to what you're doing now, it is a lost altitude. Yes?

 1:07:03

Speaker 12:  My impression of this is the earth's moon and as a result moon was the planet at one time. I mean it's why at very extreme, the box of the earth versus the need to... I think, a complete set of fingerprints?

Scott Southworth:  I can confidently tell you, my, we'll never know. I cannot answer your question. I think that I have studied and read that much of the lunar samples are basalt in composition. We have a hard enough time to get permission to study the United States so I can't answer your question. Sorry. 

 1:08:00

There are people getting their hands up but apparently we never got the formation of the moon is that very cruel insults, a marked side of object throughout the earth and basically punched out above the earth's outer part, which is what Dave had called the mantle crisscross. That separated and then free form so the moon compared to Europe has a very small metallic form today and at various state of mantle. And then also a very thick crust and crust is mostly kind of like Old Rag and ran where it all started, they moved to the basalt, a kind of big marred basalt that I never felt that enter the crust.

Speaker 13:  It holds a little bit of various new at all. Is it true?

Scott Southworth:  Yes. As a matter of fact we're working in that area and I cannot, it cannot be and I mean I haven't had included material to talk from.

 1:09:16

But there is a major work of Virginia Tech moved a study on this. There is a really interesting story about that but it's going to take a while if it were told. But somewhere, I mean I have Brenda do the slide I'll show you. The boundary to the Blue Ridge come up from the secure lines formed which called the Blue Ridge Tartan and that is the current eastern drainage divide. And that current ridge divide from the area about the rung, that has caused into the plateau area of West Virginia.

 1:10:02

The new river sandwards are in this block here and in this western drainage. All of the drainage north of there is east coast drainage. I'm checking in to your work from now on great favor that is going to tell you when that happened. That every lane submitting the deposits that we talked about tonight and you were 27 billion years ago. The real question is, is how sensitive the plateau in which the river sits is clearly a fossil landform and we don't know if we have the ability or technique to actually date but it goes back to the assembly of Pangaea would be closed the ocean to form the Appalachian chain.

 1:11:05

Drainage in this part of the world was last. Ever since we captured it as we've created the line quotient so you probably read that the new river would be as much as 300 billion years old, I don't believe that but it could be a lot more than they thought it is. So just stay tuned.

Speaker 14:  When you find something interesting do you identify it on site or do you take it to a lab.

Scott Southworth:  Usually if I can identify as so I don't need to think about it. Geologist are kind of weird that way. We always pick up things and collect things and we don't know what they are. And this is where we begin to study. So we are on, we like all things but we do try to recount tracks of our fault at least. A team of mostly...

[Laughter]

 1:12:10

Speaker 14:  Is that the place?

Scott Southworth:  Certainly because of the course. Any other questions?

Speaker 15:  You said that the price would be available online.

Scott Southworth:  I understand that this street is scary with audio-wise biz. They tell me it's been Twitted as of speak.

Speaker 16:  Have the speak gone on out?

Scott Southworth:  Yeah it would be nice if they grabbed us for advice I don't particularly like looking or hearing myself. These are kind of the cost of jobs. I lost, so right now I kind of really failed but...

Speaker 16:  Hey, maybe we're going to the town.

 1:13:04

Scott Southworth:  Well there's ah, as I'd told the woman last week, if you wanted to know where can I find anything.

Speaker 17:  Dave this is the last one.

Dave Russ:  That's right. Let's give Scott a big round of applause.

[Applause]