Geoscience Education in the Mountain State:
CATS Geology Telecourse, Fall 1998,
Show 2 Transcript

CATS Telecourse Broadcast
Geology 290
October 1, 1998

Tom: Good evening and welcome to "Geology." This is our second live broadcast. My name is Tom Repine and we have Deb Hemler beside me here. And you might notice that the arrangement is a little different up here.

Deb: What is conspicuous by his absence?

Tom: We are still waiting for the arrival of someone who is normally occupying this seat. We're going to try to get along until Dr. Bob shows up. He's been delayed slightly but we'll fill in until he gets here. Now's there's a few things we need to cover before we move on. And basically I have some housekeeping information that we need to go over. So let me just go down through the list here.

First, something that most of you have been asking about, either through your facilitators or in direct conversations with me, has been the textbooks. Well that situation has been resolved, although the textbooks are still not in your hands. Phyllis Barnhart, through the Department of Education, is purchasing the textbooks so they are free for you. They're being delivered this week to the Department of Education in Charleston and they will be mailed out early next week. You should have the textbooks in your hands no later then Wednesday or Thursday of next week. If you do not have your textbooks by the end of next week, please give me a call at the Survey at the 1-800-WV-GEOLOgy number and we'll make sure we get things straightened out and get a textbook to you. I've tried to inform as many of you as possible, either through facilitators or e-mail addresses, that we will take into account the reading assignments that have been made on the syllabus and modify those to reflect the arrival date of the textbook itself. So don't panic if you see you have to read chapters 1 through 8 for tonight and you don't have a textbook to read. We will do our best to try to modify that and get you up to speed. It's not a matter of you having to catch up. Just a matter of us having to modify what you're going to read and go from there.

We also have some new participants at some of our sites this evening. You are still eligible to sign up for the full three credits if you want to. We will make some arrangements to allow you to make up for the Saturday Exploratory you've already missed. So we will discuss that at our next broadcast once we find out how many new participants we have and where they are located.

The other thing going on is the Saturday Exploratory coming up October 10th. I don't have an overhead for this because I was trying to use technology this week and do something on the computer in PowerPoint. But they just won't come out of the machine for some reason. So...let me just read this off to you. For October 10th, the Saturday Exploratory begins at 10 a.m. and lasts till approximately 3:30 p.m. Dr. Bob will be at Wheeling Park High School in Wheeling in room 310. Deb Hemler will be at Braxton Middle School there at Flatwoods. And I think that's called the commons?

Deb: Yeah.

Tom: And I will be at the Geological Survey headquarters here in Morgantown at Mont Chateau. We ask you once again to bring some appropriate shoes and given the time of year, you might want to consider what clothing you wear as far as a coat or something 'cause it might be cold on Saturday. We'll probably go outside a little bit for everybody. You also need to bring along your implementation notebook and some sort of writing implement, preferably a pencil. One of the first things we'll do Saturday at all three sites is that each instructor will sit down and have a group discussion of the implementation notebooks--what you've written in there pertaining to last Saturday's events and exercises and experiences and how you think those might be used in the classroom setting. And after that discussion, we will each go into our own specific topics and move on from there.

Another item is some of you at some of the sites are experiencing technical problems. I know that Wayne just called in said they do not have video tonight. And I know that Paula over there in Franklin is also not on video tonight. Please remember that if you go to the web site, go to the geoscience education section, you will find information on the telecourse and transcripts of each live broadcast. We've gone through and bolded and highlighted certain information and certain content items. It'll help you use that as a study guide and bring you up to speed.

The facilitators--quick note to you. If you can send me a list of everyone at your site. I know you've done this before for me. I need a comprehensive list to make sure everybody's accounted for and we know what's going on out there. Make sure they've also filled out the appropriate forms for West Virginia University and if money is due, make sure that's forwarded also. And we'd also like to remind you that the audio bridge is now active from 5:30 to 8:30. The plan was for me to go and answer the phone but I don't think that's going to quite work here this evening. But we'll handle the audio bridge as best possible. We got cut off a little early last week. That was a communications problem but we're ok now. Just to remind you that the number you need to call is 1-800-233-3638 for the audio bridge and the code is 2287.

Two more items: One is there is a Gem, Mineral and Fossil Show this weekend at the Geological Survey headquarters. This is a kind of really neat event and if you're in the area and want to drop by, the hours are Saturday 10 to 6 and Sunday 11 to 5. All kind of nifty stuff, there's about 12 vendors, if you're interested in minerals, fossils, and gems.

The last announcement is that the date has been set for RockCamp '99. Those will be July 11 to 23. Applications are now available. We will have applications at the WVSTA meeting and you can pick those up there. Or if you need an application you can e-mail or call me or write and we'll get one out to you. Also, past participants of RockCamp will be getting copies of the applications and they will be distributing those out to teachers in their home areas. So that's kind of all the announcements.

I keep hearing this beeping in the background. Is there anybody out there?

Deb: It's Paula.

Tom: Paula, hi Paula. How are you doing?

Karen: It's Karen in Charleston.

Tom: How're you doing, Karen?

Karen: I'm doing fine. You asked me to call.

Tom: You by yourself?

Karen: And I'm by myself.

Tom: Ok. Thank you for reporting in. Have a nice evening. Deb, you have some information here on WVSTA.

Deb: Yeah, sure. The WVSTA program has been completed and we have a full set of sessions. We have about 115 sessions scheduled and it will be a full program. It's starting Thursday October 15th and just to kind of give you a overview, starting at 5 o'clock on Thursday you are welcome to come in and register. If you haven't preregistered, you can come in a pick up your packets. The exhibits will be open Thursday from 6 p.m. until 9 p.m. While the exhibits are open, we will have an opening reception which will be hosted by the exhibitors and supporters at the Shaver Center which is where the exhibits are open. There will be finger food and hor d'oeuvres and things to drink. So you can mingle through the exhibits and get reacquainted with people that you haven't seen for a while. That will again extend until 9 o'clock. We have a session set up with Flynn Scientific called, "A Chemical Extravaganza" or "Fun with Science," which will last from 8:30 until roughly 10 o'clock in the ballrooms of the convention center. While that is going on, we will also have the third annual auction. Last year the auction was canceled due to a lack of materials. But if you bring your surplus in, we have funny money or conference money that you can use to purchase these items and the item goes to the highest bidder. So bring your surplus and you get funny money for that surplus in addition to the money that you receive for registering. And then finally at 10 o'clock, Larry Oyster and Andrea Anderson have a star search going on, where they'll be looking at stars, constellations, and planets. They'll bring some binoculars, charts, and telescopes with them. So we have a full lineup on Thursday.

The conference then begins on Friday, October 16th at 8 a.m. Sessions are scheduled. The opening session will take place at 10 o'clock and Senator Jay Rockefeller will be there so we are really excited about having him. The banquet will be at 6:30 p.m. Friday with Dr. Sylvia Earl, who's a famed oceanographer who holds right now the world record for the longest free dive--the deepest, longest free dive.

Tom: Did she go down in the trench?

Deb: Somewhere close, but she was untethered in her undersea walk. So she holds the record for that. And then afterwards at about 9:30, we have a reception after the banquet where we're going to have a live band called "Big Planet Soul." There's like 11 members in this band so it's going to be pretty big. And of course, that's a typical reception for the awardees and they'll be some desserts and things there.

And then on Saturday at noon, we have the president's luncheon and Jerry Wheeler will be our speaker. He's the Executive Director of NSTA. So we have a great lineup of speakers. As a matter of fact, Sylvia Earl is in Time magazine this month if you want to check out that issue. They talk about her as a prominent environmental oceanographer, probably one to replace Jacques Cousteau in her efforts in public awareness. So we're really proud of the lineup that we have.

We want to make sure that you realize that the conference does extend until 4:30 on Saturday. Typically people think that the session ends at the luncheon on noon and that's not the case. So if you can't make it in on Friday, certainly come in on Saturday and you have a full day of sessions. We have some great workshops going on in the afternoon after lunch. Plan to stick around for a while. If you want to check out what is on the program ahead of time, you can visit the web site. Web site address: http://www.inetone.net/wvsta/. That will get you to our web site and from there you can fish around and see what great lineup of sessions we have and the tours that we have. And there's still plenty of slots available on many of the tours so make sure that you get in and register for that. There will be a meeting for any of those of you that want to meet Dr. Bob, Tom, and myself on Saturday afternoon at the end of the RockCamp activities. Right after the luncheon, which ends about 1:30, from 1:30 to 2:30 will be the RockCamp Shar-a-thon which you're invited to attend. For another half an hour while we're cleaning up and rearranging, there will be a RockCamp IV reunion meeting. Then from 3 to 4, we'll have the RockCamp raffle which we typically have. And then from 4 to 4:30, we'll have our telecourse meeting. So if any of you want to stick around and talk about the course or just get to know Dr. Bob for the first time, that will be a good time to do it.

Tom: If nothing else, coming to the raffle is always a good time because we give away free goodies. It's a lot of fun.

We've been watching the tapes and we hope you've been watching the tapes too. 'Cause remember those tapes are kind of a foundation of this whole course. I know some of you have raised concerns about how the tapes seem to be going along at a nice pace and suddenly all these terms start flying on and for five minutes they just go overboard--dips, slope, reverse, and faults and all this kind of stuff. So maybe we need to clarify a little bit, not so much what's important but kind of how you can watch these things and not get too carried away with all the jargon.

Deb: Right. For the most part, the tapes move along fairly slowly. Five, six, and seven went at a reasonable pace. When I watched eight, as I was just casually watching it, I realized that they were shooting term after term after term, talking about faults and the different types of faults, strike and slip, thrust faults, transverse faults. So it was really hard just sitting there watching, keeping up with the moderator as they were going through all the different terms. So I thought anybody unfamiliar with these terms would really have a difficult time taking notes on this much, less comprehending what they were trying to say. But the benefit of this is that you do have the tape and you can rewind and watch. But certainly you're not responsible for all those terms that they mentioned in there. I'm sure that Dr. Bob, if he were here, would tell you that when they're talking about folding, really he's not so much worried about that you understand the terms hinge and limb, which they gave in the video, but more or less that you understand synclines and anticlines, and the difference between the syncline and an anticline. And your students should know what an anticline and syncline are. These are terms that are really important in the geology of West Virginia.

Now when they were talking about faulting and they talked about dips, slips, strike slips, and oblique slips, what they are really talking about is reverse faults and normal faults, and those are fine. That's about all you really need to know. You don't have to go into a lot of detail and the different types of faults. And the distinction between a high angle or low angle fault is rather obvious in terms of the angle that the fault makes when the rock breaks. And then they went into a lot of vocabulary on stresses. Compressional of course is obvious. You're compressing. In shearing, you're moving side by side, much like a transverse fault or the San Andreas fault is. So those are obvious. But don't get caught up in the vocabulary. We want you to just understand the general concept of what is going on here, what these faults are doing, what the rocks are doing. We're not interested that you memorize all the terminology that they threw at you.

Tom: Let's explore some of those notes you have there and some of these concepts in our own way. And like we said we don't have any prepared notes here. This is live TV at its best. You have some notes here on folding and faulting. Let's start with the folding, the synclines and the anticlines. Synclinal folds are the ones that kind of give you this sort of impression like a smile. You have a low spot here and these are your limbs on the side. And the anticline is this way basically. If you want to remember anticline as anthill or "A," that's one way to do it. Syncline is just the opposite. I remember syncline as a smile. That's how I tried to remember it when I was in geology class. What would be a good way to approach this in the classroom situation? Let's say you want to talk about West Virginia geology. How would you approach anticlines and synclines in West Virginia?

Deb: Typically, generically in a classroom is the way to start out. And that is taking anything that you can stack in a classroom. I've seem people stack carpeting. I've seen people get foam. It's about this thick and it's a variety of different colors. Then you stack them one on top of the other and then you take that and you slowly compress or apply pressure on either side. And of course, it's going to buckle. I've also seen people do it with bath towels or even clay. The students make flat layers and they stack those layers on top of each other and then push in from either side. And so you get a warping effect and you can see what the layers are doing. And then once you have that, then you can go into this understanding of what an anticline and what a syncline is, and that sometimes they can be stacked next to each other. You can have an anticline adjacent to a syncline. And then of course, from there you go to West Virginia and you talk about the eastern part of the state where we have the valley and ridge in the mountains.

Tom: Let's slide apart a little bit here and look at this map behind us. What you're referring to here are these pattern differentiations.

Deb: Right.

Tom: Here in the western part of the state, we have broad colors. Over here we have these linear, very narrow colors.

Deb: Exactly.

Tom: Put that into that concept you were talking about, anticlines and synclines and the patterns they make.

Deb: Ok. If you look here to the west you don't see a repeating pattern. You see kind of a gradation here. We've got this beige color going to the purple, then going to the green. Of course, if you remember from your intro, these colors are talking about different rock units. But when you get over here into the panhandle, what you see here is a repetition of colors. You've got kind of a beige or peach color here, then you have a peach color here again, and you have this repeating green here, and you have a parallel of these oranges on either side. So what you've done is you've taken an anticline or a syncline and you've sliced the top, and all you have are these parallel patterns to tell you whether it was a syncline or an anticline. If you want to cheat you can look at the map and see that it actually indicates where the axis of the syncline or the anticline is.

Tom: What is the axis? That came up in the tape.

Deb: That would be kind of the ridge, the ridge of the anticline.

Tom: This is how you do it in the classroom. You just take some stuff and stack it. I normally have some foam that I use of different colors. It makes it a little easier. If we make an anticline here, where's our axis?

Deb: Our axis is running here, the limbs would be out here, and the hinge, another term that they applied, is a plane that goes right down through the center.

Tom: So they talked about trends, too. How can an object like this, deformation of the earth's crust, have a trend to it?

Deb: Well, the way it is positioned. The front of the table is north and this is south. And the trend is north-south. But then if you shift, you've got now relative to me, a northwest to southeast trend. The trend can change relative to where the impact came from. So we can tell a little bit about where the compression began by the trending of the mountains. We can see that in the Appalachians.

Tom: So if we go back to the big map behind us back here, most of the structures in the east are trending northeast.

Deb: Northeast to southwest.

Tom: Which would imply the force came from this direction down here. That's basically one easy way to use a geologic map to give you some real insight into what's happening. Now, when we have these repeated narrow patterns in the eastern part of the state versus the very broad, wide patterns in the western part of the state, what we're looking at are degrees of folding over here, the anticlines and synclines are much more like this. They're much tighter. So it would be narrower from one anticline to another. Or if you want to make them wavelengths, the wavelengths are much shorter. Now remember if you have an anticline, usually, although there are exceptions to everything, there's a syncline on the other side. So we make an anticline like this, there's going to be a syncline here and a syncline here. In the western part of the state, these anticlines are more like this--very broad open, rolling type anticlines. Now given that fact, and you're trying to get your students to understand what's the difference between the geography--because geography and geology often get mixed up. They're very related to each other but they depend on each other, but they're really distinct. So if we're talking about the geography, which is the landform of the eastern panhandle of West Virginia versus the western area of West Virginia, how can you relate that back to these broad, rolling anticlines versus the very narrow anticlines and synclines?

Deb: Well, you can bring in, of course, maps. That's a great place for students to look at maps if you don't have the luxury of taking a field trip. A field trip is a great thing to do. But if you don't have that in the classroom you bring in the use of a topographic map in addition to the geologic map. Also what I use in the classroom that has been very beneficial is a raised relief map. That probably drives that point home faster then anything. The students actually see the relief instead of trying to interpolate it from a topographic map. And that's difficult for students that are in junior high. But if you have a raised relief map, over to the west you can see it just dimpled. It's just a plateau that's been dissected by river drainage. Although it appears to us to be mountains and hills, the students quickly see that its a relatively flat lying plateau--that really the relief is only created by the drainage. And as you move over to the east and you look at the eastern part of the state including Virginia and Maryland, you can see the ridges. You can see that there are distinct ridges and distinct valleys, and then when they take a look at this, they see the repeating patterns. And we talk about anticlines and synclines and how to determine whether it's an anticline or syncline from this repeating pattern which we'll go into in a minute, you can then see how the geography and the geology are related or not related. And some of these cases over here in the east, the syncline, which we've said looks like this, actually is at the mountain tops. If you've ever gone through Sideling Hill you'll see that. That's a classic example. If you look at Sideling over near Hagerstown, if you look at the top it's shaped like this. That mountain is actually a syncline and so the geology and the geography can be two things that don't really seem to relate much.

Tom: So you're telling me a syncline can make a mountain?

Deb: I'm telling you a syncline can make a mountain.

Tom: That seems very contradictory to what most people would think. They think synclines would be the valleys.

Deb: Well, that's what you would naturally think. But it has to do with the rock that happens to cap the feature and the fractures and where the stresses came from.

Tom: If this is Sideling Hill or any other type structure in the eastern part of West Virginia, these limbs, if they have what we call competent or very hard or resistant rocks in them, they'll erode as quickly as the interior. So you might wind up with these limbs literally sticking up above, making a mountain on this side and a mountain on this side. And that's very common in the eastern panhandle. Now if you've ever been to Canaan Valley, it is like this. It's an anticline. What's happened is when those rocks buckled, this area through here was fractured and cracked, and through time it's been removed so the mountains you see there are really this area here, and this area here there's the valley down through the middle. That's why you often hear Canaan Valley called one of the highest valleys or an alpine valley, because it formed in a very high spot. It formed at the top of an anticline. We call that a dissected or a breached anticline. And it's a very common feature, especially out west. You find a lot of those things. The Black Hills are a very good example in that.

Let's go to a general overview of anticlines and synclines and hopefully most of you have one of the small maps here right behind Deb that was handed out last week. It gives you the same patterns as this one but in a much more generalistic sense. And you can still use it to figure out anticlines and synclines from that. Remember, the colors on the geologic map are really important.

Let's move on to faults in West Virginia. Are there any faults in West Virginia? Do we have any problems from seismic activity in West Virginia?

Deb: Oh, yeah. Most people would think that we don't have much in the way of earthquakes or a problem here in West Virginia. But as you might have heard this weekend, we had a little episode. We had an earthquake that actually shook the northern panhandle which they believe the epicenter was somewhere in Ohio.

Tom: It was right along the Pennsylvania-Ohio border. For those people who were on the RockCamp II trip last year, that's right where we were. We missed it unfortunately. That was a 5.1 or something like that.

Deb: And not too long ago, about a hundred years ago, we had a really sizeable earthquake that was felt across the entire state. That epicenter occurred down in Virginia near a town named Perrysburg. It was called the Giles County earthquake. That was in 1898. We do have seismic activity in West Virginia and there are a number of faults that are related to this mountain-building process as well as some tensional activity that occurred when the continents were pulling apart.

Tom: They're not the type that you might find out west or in the prominent earthquake zones. We normally are affected by the one down in Virginia and some of the ones up along the St. Lawrence Seaway. And also the one out in Missouri, the New Madrid. That would have some potential to bother us. And maybe we even mentioned that one on the tape.

Deb: No we didn't.

Tom: I thought that was kind of interesting. That is located out near the St. Louis area and there are many different thoughts as to what the New Madrid fault is all about. Most people speculate that's an old suture zone where the proto-continents were coming together, and when they started to drift apart, that stopped and stayed in place. But there's still some slight movement along that. Occasionally you get some earthquakes. In 1811, 12, or 1810, I forget the dates exactly, there was a magnitude 6.5 or greater earthquake in that area that literally affected a very large region and was felt the whole way up into the New England area. So we are actually in a moderate seismic zone as far as damage. So it's something to keep in mind when you're talking to your students, that we are not out of that zone where we will not have any damage. If you go through the historical records, when that earthquake happened down in Virginia, there was actually a student at what was then called Fairmont Normal School that was injured in the mad rush to get out of the auditorium. She fell down some steps. She wasn't injured by the quaking but those things happened. The other item, faults we talked about. And we talked about anticlines and synclines, which are structures that they talked about in the video. And the other thing is the often very confused and very hard to understand unconformities, disconformities, nonconformities, all those kinds of conformities or not conformities. How would you approach that with your kids? What's the really important concept in there?

Deb: The important concept here is not to go into the vocabulary but to have them understand that part of the rock record is lost. That you don't have the entire rock record there to interpret the information from. What happens is you've got deposition, deposition usually in some type of environment like a lake or river or a sea. It is then exposed. When it is exposed, it undergoes erosion and through this erosional process material is sloughed off. And part of that rock record is lost. Well, then the sea rises or for some reason there's a depression. Water levels rise for some reason, then sediments start to accumulate again, and then at that point sedimentation occurs. If it's buried far enough and long enough, then you have rocks being formed. So the important thing is not to go into the vocabulary. They talked about angular unconformities. They talked about nonconformities and disconformities and that's fine if you're a geology major. But really what we want the students to understand is that we don't always have the entire rock record to extrapolate from. So you need to really pay attention to the fact that some of the rock record is gone and you have to look in other places to interpolate what happened, but you can't really rely on what you've got. An unconformity is then missing parts of the rock record.

Tom: But the important part is to recognize either something's missing or something didn't happen.

Deb: Right.

Tom: That's the important part. I think what we're going to do now is take a early break and get ourselves reorganized and we'll be back.

(BREAK)

Dr. Bob: Greetings! I'm here. And it's a beautiful day for a field trip again. It's just fantastic out there. Well, we've been talking about structure. You've been talking about structure and I've been thinking about structure all afternoon. One thing that in the presentations on the video there was a lot of extraneous material in there. In the context of a one hour show or two half hour shows, there's a lot of words that could be said.

Deb: Actually it was a half an hour at the end. It was every other sentence was a vocabulary term. It was really scary.

Dr. Bob: I often think of it like sticker shock in an automobile. You go into the new car lot and there's the sticker shock and you can see a television and the amount of material. David Attenborough's "Life on Earth"--one minute you're in Antarctica and another minute you're in the desert and you're head's spinning in the first five minutes of the show because there's just so much to absorb. So we need to just kind of slow it down. And besides, until the text comes, and that should be hopefully soon, early part of next week, there's no problem at all. We will be working slowly on some basic information and this allows us a great opportunity to really work on West Virginia.

We distributed to everyone a sheet of paper. If you would all pull that out. It's a sheet of paper with light green and--not light green I guess--N's and R's and browns and greens on it. Well on this, first, let's talk about what we see. We have a dark black line down the center. We've already cut ours. If you haven't already cut it or if you have the scissors there, cut the lines along just the one dark line from the tips of my two fingers so that the sheet will separate. So that's a simple cut and I'll continue to chat while we go around and talk about this, and share the scissors, that this particular cut shows displacement in the fault. Now, what do you think these N's and R's stand for?

Deb: Probably magnetism.

Dr. Bob: Yep, magnetism, in grades that must be hard to really grasp. We know there's magnetism. We know the earth has a field. What do you do in class with that?

Deb: We typically use a bar magnet and then you get iron fillings. You put a transparency up on a overhead. You put the iron fillings on top of the transparency and you slowly drop the iron fillings down. You can see the magnetic field start to develop with the iron fillings around the bar magnet. That gets them to start seeing a magnetic field. Then we typically go into a series of activities using magnets and doing the simple north to north pole and north to south pole to see attraction and repulsion, just to get them used to the idea there is a north and a south pole from the magnets.

Dr. Bob: Now what causes magnetism? That must be taken on faith.

Deb: It's an extremely hard concept because in order to understand magnetism, you have to understand electrons. And in order to understand those electrons, you really have got to be further up in your education. So for the junior high and elementary kids, it's a really difficult concept for them to understand. It's actually bordering difficult for a lot of the high school kids.

Dr. Bob: Yeah, I think it should be. It is not an easy concept and then when you try to extend it to why the earth acts as a bar magnet, that is also very difficult. We can't see what's in the center.

Deb: Typically, the textbooks don't even address that. They don't address the fact that there's a molten layer in there moving and that movement is what is actually creating this magnetic field. They just typically give it to you in the book that the earth acts like a bar magnet. There's a north pole and there's a south pole and believe it.

Dr. Bob: Yes, that's why I say you take it on trust. They can talk about a dynamo and things in motion and electric fields, magnetic fields, and that there is an interrelationship that you can change magnetism and use a bar magnet spinning to create an electric field, and all manner of a magical type of things. But it is downright difficult. Since we talked about that and we're leading into it, let me point out that the mineral that we most often talk about as being a magnetic mineral is iron, and iron and oxygen. And if you look in many geology texts, you see that representation. Three irons and four oxygens. The mineral is magnetite. Wouldn't you know I like to write it in a different way. I suspect you have seen this before, too. And I would like to write it like this.

Deb: That actually makes better sense to the chemist. Because it gets confusing to students when they're talking about oxidation numbers and trying to look at that, it just doesn't make sense.

Dr. Bob: Right, and do you use terms? I often find myself using terms that seem almost archaic to what the youngsters are doing now in high school and such. You talk about balance or the charge. How do you phrase that?

Deb: We certainly would in chemistry, but when we're talking with the youngsters, we tend to not go into valences too early.

Dr. Bob: Ok. When would that appear?

Deb: The sophomores will typically have valance. Some might try to introduce it in, I've seen it introduced in the ninth grades and casually in the eighth grades, although there isn't a great comprehension, I don't think, of what valance really means.

Dr. Bob: And the gain or loss of electrons really becomes again something that we can't see and yet it's a fundamental aspect of everything that we do in looking at rocks and minerals. What we are looking at here is that every oxygen gains two electrons to become the oxygen ion. And since there are four of them, using some simple mathematics, we have to have a balance charge to balance the -8. Each oxygen atom in the participating mineral has to have a balance charge of +8 somewhere. And that's how we start looking at these two little rascals and the fact that there's one of one type and two of another type in order to obtain the 8.

Now for a moment, let's talk about the two types of conditions we find for iron. One, the iron which has lost +2 electrons. And if you use the simple bore model atom which is really instructive, don't you think? It just makes a lot of sense. You don't have to talk about spin and all kinds of these things. You just draw it on a sheet of paper. And if it loses it's outer two electrons, which are all alone in the outermost, the outer shell, it's a +2. The other form is iron +3. Now this really takes some energy because you've got to take not only the two outer ones but one more. You've got to rip it out from a filled shell, at least temporarily filled. That's not easy.

And then there are two other words we sometimes run into trouble with because of a component of one of the words, reduction and oxygenation. Now the word that provides trouble for us is oxidation. Because we see in that word or we think we see in that word the component of oxygen. Oh, the oxidation is the combining of one element with oxygen. Au contraire. The best way to always think about this is that reduction is a loss of electrons and oxidation is a gain of electrons. So a loss and a gain. What we have is an unusual composite. What we're talking about, you say well both of these ions have lost electrons, and how does that make any sense? Well, what we're looking at here is that the iron +3 has lost an extra electron, right? And this one you see then is in the oxidized state. So oxidation and reduction are going to be a reflection of losing electrons and gaining electrons. And the iron in the +2 state is the reduced iron. The iron +3 state is the oxidized iron. And looking back at our equation for magnetite now, we find that it makes sense to say if we have to get a sum of +8, one of them has got to be a +2 type and the other of the species has to be a +3 type. The only thing that makes 8 is that there is one of +2 and two of the irons of +3. So that the total charge is +2 and two times +3 equals +6, and the sum of these two is +8 and we have a balance: +8 on one side and a -8 on the other.

Now in nature there are very few minerals that are naturally magnetic. Magnetite is one and another mineral called ilmenite is another. Ilmenite is an iron titanium oxide and wouldn't you know, it has the same type of situation as the other. And ilmenite is not quite as magnetic, but the ilmenite has an equation FeTi₂O_4. And because there are these forms with +3 valence, that's why these rascals are naturally magnetic. It has to do, as you said, with electrons. It has to do with the nature of the participating material. So in nature, we only find naturally magnetic material that has this general type of structure: an ion of the +2 type and some ions of the +3 type. And magnetite and ilmenite are the only at all common, natural magnetic material. That's an interesting departure. Why does it relate to our figure now again of N's and R's. At least through most recent geologic time, we don't know if magnetic reversals have occurred. We suspect it could have, but we don't know if it occurred very regularly in episodically billions of years ago. But we do know from a very close analysis of the rocks, especially in Japan and other volcanic island areas. We obtain the absolute age of the rock by the potassium argon method. We talked about that last week. And then we looked with very sophisticated equipment at the magnetic orientation. The orientation of the little grains of magnetite. Though they're very rare in general, they're oriented according to a cooling phenomenon, and it's called the Curie temperature. You know until it gets down to the Curie temperature and lower temperatures then, that that little magnetite grain can shift around. As a matter of fact, even magnetite grains in sea-floor sediments can align or be aligned, or lake sediments. In rivers it's pretty active. All those grains are going to be shunted around and moved. But in this type of situation, individual grains of magnetite cool, and N stands for normal, what we experience today. And R, reversed. Now we don't know, exactly know, what happens when the magnetic field changes or shifts. We don't know if its a total 180-degree shift. We think not. We're pretty convinced that the magnetic field is not just disappeared totally but rather it weakens. There's a weakening and then when it reforms, it forms in the opposite sense. The earth doesn't rotate unusually or spin. We've never lived through this. The last time was about 780-thousand years ago, the best evidence we have of the last reversal. So that's a long time ago. There's no sense of a periodicity to this. So it could happen again. But unfortunately, it probably won't happen in our lifetimes.

Deb: Are there any precursors that they've detected?

Dr. Bob: We don't have the ability to get that narrow and precise. The other possibility, what else do we teach to youngsters about the importance of the magnetic field? That is, the earth has a magnetic field and what does it do to the cosmic rays?

Deb: We've got the Van Allen belts and we're shielding ourselves from a lot of the cosmic rays given off by the sun.

Dr. Bob: Right. Exposure to cosmic rays presumably could...?

Deb: Kill us.

Dr. Bob: Yeah, could not be good. But we don't find in the fossil record any evidence that there is a mass extinction associated with this reversal of the magnetic field. That's why we don't think there's any precursors. We don't think that it happens over a prolonged period of time with a total absence, because which critters would tend to be radiated first?

Deb: The land critters.

Dr. Bob: The land critters and the plants on land. And we just don't find any evidence for that sort of thing. So, this information then, as you have the piece of paper before you, fold it up, is the way the sea floor looks today along a spreading center. And I'll use a pen now and lay it along those dashed lines. There's one there and there's one there. And the pens now reflect the location of the current spreading center. Now you say, well, is that a high point or a low point along the spreading center? There are some excellent maps out by the National Geographic. And I saw an article that the National Geographic is going to put a new map in all the classrooms across America. It's going to cost a million, two million dollars or so but they were going to do that sort of thing.

Deb: Great!

Dr. Bob: Yeah, that's marvelous, because those maps are quite often looked upon as just the most spectacular of all. But when we look at the sea floor, we find that the floor of the sea, there's a trough along these spreading centers. And the reason that there is a trough is that when there's a pull-apart, what happens in the center? Well, it happened here, the blocks fall down. So that when I turn it on the side, you see that there is a depression or valley in the center. So that at the actual pull-apart zone, there is a type of fault and a displacement. We talked about normal faults and that's a normal fault. It's like a keystone. You pull it apart and the center block falls down.

Deb: And we talked about tension.

Dr. Bob: Ok. That's tension. That's pull-apart. Now at the same time this is happening, magma is coming up because this is a pull-apart zone. Well, what about the temperature of magma? It's higher. And if a material is warmer, what about it's density? As it becomes warmer it's less dense, and therefore it will rise. Therefore on the edges, the mountain on the edges forms because it's hot material. But as it moves off the spreading center, what happens to the temperature?

Deb: It cools and becomes more dense.

Dr. Bob: It cools and becomes more dense and therefore the sea floor sinks. And if there was a volcano here in the sea and it reached the surface of the sea, all this is moving at rates of two to four centimeters per year. Pretty slow. Like the growth of your fingernails. So if a volcano does reach the surface of the sea, the waves cut off and plane off the top. That volcano is going to ride along on the block, and through millions of years, it's going to cool and sink, and therefore there could be flat-top volcanoes deep underwater.

Deb: Which we see in the Pacific.

Dr. Bob: And we see in the Pacific in great numbers, yes indeed. So, as an ocean basin becomes older, it also gets colder, if you want to think of it, and therefore what about the depth of the water?

Deb: Deeper.

Dr. Bob: It becomes deeper. And for an old ocean basin then, what happens along the margin of the continents? As the ocean basin gets older and older, what happens to the water that may have been on the edge of the continents? As the sea level changes now, if the ocean basin gets deeper, where's the water all going to go?

Deb: It goes into the basin, the land further out.

Dr. Bob: So, sea level starts draining off the continents. It starts moving off the continents as the basin gets very deep. And of course, where are we now with respect to the Atlantic Ocean, it's a pretty big ocean and it's quite old. Fifty-, sixty-million years ago when the sea floor was younger, warmer, and shallower, an arm of the sea was way up along the central part of the United States as far as the southern tip of Illinois. And in the intervening 60-million years, we've seen a gradual, what we call in geology "off warp." The sea is moving off and therefore we have these rocks of Cenozoic age all exposed. But the sea is just not at all going to come up to southern Illinois anytime soon.

Deb: In the case of the Keys, which are an ancient reef, would this be the same phenomenon that would have exposed them as well?

Dr. Bob: Well, the term there is ancient. You see, the carbonates in the Keys are Pleistocene age. So we're talking only in the past two million years tops, although there's discussion about maybe extending the Pleistocene back two and a half million years. That's the details of what we do as geologists. We argue about where the boundaries are of ancient times. So that the big factor in the Pleistocene, of course, is glaciation. And the glaciers have caused a different type of sea-level alteration. And it is that sequence that better explains the reason that we have reef structures. There's a Miami oolite. In Miami property, you find a limestone with little, it looks like little B-B's. And that's all calcium carbonate because the calcium carbonate was sloshed back and forth as it was forming in the warm waters, so that the limestones there reflect the time of deeper water. Perhaps less ice then there is today. And then as more ice formed, that more rapidly caused the drain. Because in two million years changes in the sea-floor are not great. But in two million years there have been multiple glaciations of significant numbers. That sea level is just bouncing up and down in the context of looking at it in Pleistocene as compared to 150-million years for the creation of the Atlantic Ocean. And you know in the context of all this, we then look back at our model and say today we find these mirror images that are N's and R's, and they're a mirror image on each side of the spreading center. Let's just look at one for a moment. Where is it oldest? Out here. It's youngest right at the pen, that's where it's forming. And it's moving out. There's tension. Just look at one of them for the moment. But the spreading center is not an easily drawn line on a sphere. You can't draw the straight line without running into some problems. And what happens in nature then is that there are tears and offsets. In a more fanciful term in mathematics, it looks like a step function. In other words there's a step, like a tread in a riser to the step. And the distances between each step are not uniform. But the spreading center is chopped in pieces. So, if we wanted to look at this in the geologic past, maybe 60-million years ago, the next thing you do with this is that along each of the contacts between the darker, greenish brown is folded, like an accordion fold. Because what we want to do is put this all back together as it was 50-million years ago. Hiding all the color. I'll take it off here. And this is why you use the paper clips.

Deb: I haven't finished folding it. The way to start this is once you've got the cut made, then take it and fold it right along the dashed lines first. So make your fold across this dashed line and then again along this dashed line. Once you do that, it will make your folds easier. So once you've got your folds, you then kind of fold it over in half and peel this back so that you're folding right along the edge of the white. Like this and like this. Do that again on this side so that all you have exposed at this point is a sheet that looks like this if you fold it. Then you work your way out. You take and you fold along this next line between the green and the yellow on both sides so that you kind of bring up a different layer every time. And then you push that apart and fold along the next color change.

Dr. Bob: Some of us learn a lot more by building the model then by trying to read about it.

Deb: So that what you're doing is gradually working your way out.

Dr. Bob: Of course in the classroom, what you can do is build a black and white model and let the youngsters use crayons to color it, because the color copy is usually too expensive to engage in. We're going to be doing other model building and I'll show you a more grander style of things, but it just gets too expensive.

Deb: So once you've finished, now you have a series of folds where each one of these will come together and meet in the center as you work your way up.

Dr. Bob: J. Wilson, who had many, many years ago gathered information and was a great synthesizer of information that had been gathered throughout the world in geologic facts, had come for a three-week visit where I was finishing my doctorate. And as a student then, I got to ask him questions, take a seminar from him, and it was a great opportunity. We often try to expose ourselves to some of the people who are at the cutting edge. Sometimes it's just one lecture. Sometimes it's a great long time period. For example, when we have the WVSTA, when Dr. Bakker came, it was great. This time, who's coming?

Deb: Sylvia Earl.

Dr. Bob: And she has been recognized. Did you find the magazine article?

Deb: It wasn't on the newsstand yet. You must get yours through the mail.

Dr. Bob: No, I didn't get it yet. I read about it. That's what, Time magazine I think. She is going to be the principal speaker at the WVSTA meeting in just a couple of weeks.

Deb: Two weeks.

Dr. Bob: Two weeks at Snowshoe. And she was recognized as the most important perhaps marine environmentalist of our time since the passing of Jacques Cousteau. And that's pretty heady company. So this is a great opportunity to listen to and talk with a master.

Now these are just crinkles. This is just creating a model. These are not anticlines and synclines yet.

Deb: No.

Dr. Bob: These are just folds because we are going to try to portray in our model the effects of time. And making models is really a tricky business. We do it in so many different sciences. And we have great difficulty in working with the earth in replicating time, because things happen so very slowly and you cannot duplicate that. You just can't do that. And rocks that deform effectively like plastics when you try to do that in the short term, they snap and break. And you can't rebuild the actual load that these rocks must be under deep within the earth. So we're going to do separate models in a moment with regard to faulting and folding.

Deb: Once you've got your folds completed, what you want to do is take a large paper clip that is slightly sprung. You don't want it to be really tight. You want to kind of bend it out just a little bit. The large ones work the best I think, although the smaller paper clips, if that's all you have, will work. So you slightly spring it and then you fold it up like this and secure the paper clips right at the base of your fold on either side. And you're ready to begin your demonstration.

Dr. Bob: The reason you want these paper clips slightly sprung is that if they're real tight and you start pulling this apart, paper clips go flying across the room.

Deb: And you tear your model.

Dr. Bob: So you have projectiles and wounded students out there.

Deb: That's right, wear safety glasses.

Dr. Bob: So I'll put it on the overhead here to demonstrate the details. We have brought in now all of the colored units of R and N. We've put four paper clips and we have these flaps. Now this is the underside. We're looking, if you will, from the center of the earth out. We've got a Jules Verneian trip here through Mt. Snuffles and are examining from the underside. On the top, you can see when I pull it over like this, that these two units themselves are offset. And that's because when I bring it up on the surface, the spreading centers, the two spreading centers now are still offset. They have been offset early on in the formation of these tears as the tension is pulling the continents apart, actually. There is a model formed where the spreading center is going to be torn. Now, on my model here, I'll just, notice while there is a fault, that there is displacement along here. This, the displacement of the fault, indicates that there has been slippage where I now put the pencil. That's where the fault is. But the fault just ends. It dies out. Faults don't go on forever. There are places where the fault just ends. And the movement is going to be very interesting because we can see here that the distance between the two spreading centers at this point in time long ago and far away is approximately an inch and a half. Something like that. So we'll keep that in mind, that a long time ago this was the displacement of the original fault zone, or the spreading center along the fault zone.

Now our eventual task is to again add tension. We're going to pull it. And what I often do is I put my thumb down here and brace it with a finger underneath and my forefinger and middle finger are up on top so that I have some fairly uniform pulling power--tensional power. And for the moment, let's just pull it out as if it's happening with a current magnetic field situation. And lo and behold, we find that the new material that's being added has the same orientation as the current magnetic field. We also see this, across here, there has been no change. That's no longer an active fault. And over here, this no longer is an active fault. But what is happening is that along this zone, this has been moving in that direction. And this has relatively, has been moving in this direction. Here, this is moving in this direction again, but this piece is moving in that direction so that's not a real transform fault segment. Now if that sounds a little bit bizarre, realize that right here again everything here is moving in that direction. But on this particular unit, this part of my spreading center is moving that way, this part of my spreading center is moving that way, you see. And do I have these in relative sense now on opposite sides so the real place where there is a transform fault is right in here and right in here? That's where the transform fault continues to grow. And until you actually sit with this and work on it, this overhead doesn't do it justice.

And then you see as you continue to pull, we're now going to talk about a magnetic change. And therefore, the material that forms, all the magnetite is reversed and magnetized. And it pulls out there, and now the transform fault continues to grow between my two forefingers here and over here. But the rest of this material, look at the location here. I call your attention to the fact that at this point in time, we have that edge of the normal right about aligned with the middle of that one. We'll see with time if that changes any. You pull out the next one--oh yeah, that is moving. Every once in a while, have the students put down little marks across the way to see what's going on. What's happening up here, you see, is that, that literally became frozen in place. That hasn't moved on either side with respect to one another. The only active zones are between these fragments here. Now let's see, let's do that some more and see and only where the new material keeps coming out, the older material literally looks like it's welding to the opposite side of what had been an original transform fault. Now the new transform fault stuff is down in here, and the very early one, look at how far displaced that is. But what about the displacement of the spreading center. The spreading is about a inch and a half apart. So the spreading center hasn't moved. The spreading center locations on either side of the fault have stayed in the same place, and so forth on to completion, which means today. And the paper clips fall off underneath. And that's where we are today. The spreading center on either side still about an inch and a half apart. Material out here and material out there has remained locked. However, right here, where had I drawn that circle, gosh, that was all the way over there. Yeah. So this is not an easy concept but it probably is easiest to understand how these mirror images come out with the normal and reversed magnetism. I would think that the explanation of the transform faults are complex enough to try to do some but not worry about it.

Deb: This is a really good model because the ones in the textbooks typically just have a sheet of paper with three slits in them, one out on either end and then one in the center. And then you take two smaller pieces of notebook paper and feed them through the outside and then bring them to the middle and then you pull out on them. So you don't really get a feel for this faulting that occurs along the Mid-Atlantic Ridge. All you get is kind of a spreading center. But then they don't really make the point that the crust is being destroyed somewhere else. So you really kind of develop a misconception if you're not careful.

Dr. Bob: You might see some student come up and say, is the earth getting bigger? And you say, great question. Because it looks like in this model, where there are spreading centers, the earth's getting bigger. But the answer is that somewhere material is also being lost. On balance we lose about as much as we gained.

Now, we related to this discussion that as this material comes up warm, it's high and as it cools, it becomes more dense. And that reflects to a neat model called isostasy, sort of like floating something on water. So if we could revert to a little demonstration, we have at the front table a baking glass dish. Good sturdy one too. It would be pretty tough to break this, but it's good and sturdy. It's all fired along the edges, the reason that it's nice to be clear. Now some of these plastic containers are fairly translucent and there are some that I've seen, shoebox types, that are almost perfectly clear. And then just get a piece of wood, floating there, and our piece of wood is floating. Now the water is not coming up on the surface but I'm going to put a load on this. The load could be anything. In fact there are irregularly cut blocks. I'm going to load it and you see that the surface of the original is going down. If I put another load on it, it's going to sink. Now continents don't do that sort of thing, but if we had this block cut so that it almost fits snugly in this, then we have a chance to try and keep this floating without tipping. The point is this: that why are there still mountains in the Appalachians when those mountains formed 200 and some million years ago. Actually they started to form 300-million years ago. There's been a great opportunity for erosion. Shouldn't it be flat?

Deb: Well, we've never heard this before, actually. Most of us think, no, it's probably typical erosion. We expect them to still be there. But the video brings out a very important point which most of us probably learned for the first time. And that is they still shouldn't, they shouldn't be there today. They should have eroded away by now.

Dr. Bob: Yet what happened was that sedimentary rocks in general had gotten caught in the great vise of continents colliding, and sedimentary material became contorted and deepened a great thickness. And in effect, this rock was deeper below the original surface at which it formed, like the crust, the upper part of the crust. So in effect, it looks as if mountains have roots. There is less dense material that has been pressed together and pushed down. Now, talk about taking things on faith. We have, as geologists, looked at a great deal of information by remote sensing of the earth, primarily through seismic information about the earth's interior makeup. And we find, and this was independently done by Japanese geologists and geophysicists, that they found a zone of unusually low density material at the boundary between the mantle and the outer core. And they think, the hypothesis is that, that deep through the mantle there are sediments of Cretaceous age that have been closed as India closed on the subcontinent...

Deb: Oh my, that's a deep root!

Dr. Bob: That's a deep, and it's, it sank but there's no reason directly, it didn't have greater density. Something happened and a piece broke away and just nose-dived down in that deep. Now this is a startling thought, that material could go all the way through the mantle in about 50-million years. But the geophysical information and the seismic data really looks like that.

Deb: How did it fight density?

Dr. Bob: We don't know. We can't get at it, we can't drill it. Phase change perhaps in the way the atoms are put together in the molecules. Or another possibility would be that maybe it got caught on the downside of a convection current. Maybe it got dragged along, we don't know. And there is, this information is by no means uniformly believed. There still is doubt because it just seems so unimaginable. We've been through so many things in the past 20 years of unimaginable geologic phenomena that it's important that we hear a few voices out there with new ideas, new theories. Well, what happens to these mountains, as they erode mass is taken off. And when mass is taken off what happens to that low density material that had been in there before?

Deb: It rebounds.

Dr. Bob: It rebounds. And it's called isostatic rebound. Now we say, and what really happens to materials at the crust of the earth? And I'll say, there's another model for this. What if the load we put on the earth's crust is temporary? Ice, 10,000 feet of ice has some significant mass. And it depresses the crust. Moreover, we believe the thickest ice would have been over Toronto and in Canada. But if there is a great mass there, what if out in front some place the crust bulges up a little bit. The hypothesis is that maybe there's a bulge that had occurred when the glacial weight caused a depression of the crust. Because what we find is that once that 10,000 feet of ice melted, there is a slow rebound. It is still rebounding. It turns out that there is a hinge line. It's actually as if only part of it was affected. If I put my hand like this, the northern part was down and then it's coming back up. And the reason we see this, we find lake sediments along the margin of the lake and they're tilted. They're not horizontal. Are lakes at an angle like that? No, not too often. We especially can find this even along the Minnesota-North Dakota border in what was given the name Glacial Lake Agassi. One of the most spectacular aspects of this is that the Baltic, the northern Baltic, is literally draining because of the Finnish-Scandinavian ice shield. When that melted, now the northern part is rising in glacial rebound and it's literally dumping the water out of the Baltic, the northern part of the Baltic. In North America, we have one lake that is now fresh water, Lake Champlain, between Vermont and New Hampshire, Vermont and New York. But a long time ago it was a marine condition. When the ice first melted, the earth's crust up at the St. Lawrence was still so much depressed that as sea level rose as the ice melted, marine water came in all through the St. Lawrence channel and into that zone between Vermont and New York, and it became the Champlain Sea. But then glacial rebound and rain water literally flushed it out, and now of course it's still a significant body of water but it's fresh water. And in the Baltic, there were all kinds of things. It would go fresh water, marine, fresh water, marine as new openings occurred as the ice melted. But this is called isostatic rebound. It is a very interesting phenomenon.

And how was it first discovered? A story--the British, in one of their countries within the commonwealth and their wide holdings, was India. And they went with surveying equipment to India and the leader was of the British Navy and his last name was Everest. So they crisscrossed India. There's much interesting with respect to this, surveying in great detail. And finally years later, they came to closure. And when they came to closure it wasn't perfect. Now if you would all know and understand something of the British mind set, this is real uncomfortable for the British. Why didn't we get it perfect? It really should have been perfect. And one of the surveyors says, you know, the only thing I can think of, our instruments--even though this was the 1800s--should not be this far off. They missed it less than a meter. After years of work all over India. And he said, but when you think about it, what do we do in order to survey? We set up a tripod. We have a plumb bob, a heavy weight on a string. And we use that to center the very center of our optical equipment because we say that that plumb bob is usually pointed right to the center of the earth. And the only possible way we could be wrong in that is if our plumb bob isn't working. He said, you know where we could have gone wrong is closer to the mountains. Because the density of the earth below the mountains was different then what we expected it. It wasn't uniformly dense at depth. The mountains have roots. They change ever so slightly a deflection in the plumb bob, and that's why the survey didn't come to closure exactly right.

Deb: Well, this is kind of like one of those "rest of the stories" because they mentioned it in the video. They mentioned the plumb bob and the fact that it didn't line up properly, but we didn't know what the whole story was.

Dr. Bob: It's a neat little story that reflects scientific thinking. You know, quite often you have a problem and you look for a very extravagant answer. I always call them Dr. Bob's cannons. And the first one is: keep it simple. The most elegant explanation is sometimes the simplest rather then the most complex. My second one is: draw a picture. And that's what you draw. You draw a picture of this isostasy.

Ok, now let's move that off and go to the next structural aspect, because you see what happens with the mountains is that, what you see today, you're looking at a deep core remnant of the Appalachians. But the rocks are not flat-lying anymore. The rocks are folded because what happened was that these sheets of paper reflect the rocks--there wasn't tension. It was closure of Africa and North America. And this type of force is compression. It is just one simple fold, rather it's a series of folds. And we talked about folding and the rocks have deformed in a nearly plastic manner. Now you talk about plastic and elastic things, in what grade do you usually get into that sort of thing? You work with springs.

Deb: Oh, early in elementary grade. Actually, a really neat exercise is you take Bit-O-Honey and the kids kind of play with it because it kind of bends and its malleable. Then you stick it in a plastic and you whack it against the side of the table and it shatters. So they see how plastic it is. But if you apply a strong enough force to something, it snaps. Much like what the rocks might do.

Dr. Bob: And also it's a factor of the time at which you're applying the force. Because when you squeeze, you're probably squeezing slowly and you're drawing it out and working it out. When you smack it, all that force is essentially instantaneously applied along a very narrow surface, along the edge of the desk. So you have applied all that force. It's a lot like wearing high heel shoes versus flats on a piece of linoleum. Because even if the weight of the person is not great, if you concentrate all that mass in a very small surface area, lots of dimples in the linoleum. As a matter of fact, the other analogy, and we'll talk about it in glaciers, is that's why you have ice skates with very narrow steel blades. Because you're taking your body mass and putting as a force along a very small area so that you can get pressure melting. Because it's much easier to glide on a thin film of water then it is steel to ice. And then if the temperature is cold enough, the water that you just formed refreezes. Usually in some of these things it's just a pool of water, a slurry behind it. So what we're talking about then is features that are models that we can build. And although this is more elegant, I'll just put this on.

You can take a sheet of cardboard and build a model. Now this is a type of situation where the rocks are dipping off on either side. This is going to be a three-dimensional model such that you will cut it out and fold it there. And that's going to be the picture at depth. This picture is going to be the surface that we see on a map or if we are flying over, like the geologic map we showed before of the state of West Virginia. And the rock types are going to alternate. When we look at this type of structure, we see that the oldest rocks are in the center and the younger rocks are out on the edge. This is an anticline. This particular structure, you see what you do, you cut it or fold it here, put a crease in there, and you wind up making a block, a block diagram. Let's take this, and you can do this and make up a very simple one, let's take this out and have Deb fold it. And just fold it along the creases, you don't even have to cut. Just fold it along the creases. Because the next model, you could do a syncline, where the oldest rocks are now on the edges and the youngest rocks are in the center. But on this particular one, this is left blank to let the students fill in. What would they expect to see? Essentially connect the lines just as this letter "D" is connected. So what is created then is a, what we call, a block diagram, a block diagram of the different rock types for an anticline or a syncline. You usually have to use a piece of tape to put it together and in cross section, this looks a lot like West Virginia. Here are, this is a road with some tunnels, probably more Pennsylvania. And the rocks are dipping in certain places. That we use a measurement of strike, and strike is the exposure. The strike contact is along here. And this particular rock is dipping in the direction shown by my overhead pen. The dip angle is the angle between the horizontal and the upper surface of the bed. It looks like about 45 degrees. And you'll see this little symbol, the upper part of the appearance of the letter "T" is the strike. The short stem is the direction of dip. The rocks are dipping in that direction. Over here, if you were to find a map, you'd find this one dipping like this. This rock is dipping like that. This rock is dipping down in here. This rock is dipping there. So you have synclines and anticlines, and that's really the picture of West Virginia.

Now, Deb folded this little model. These are something, if you could just come to the center with Deb and I, a little model is a block diagram. That's the surface and these ends are something that you would fill in. And the other ends maybe have the students do. And we didn't even use any tape. You see we've got a little three-dimensional block and the students can fill in. And these types of things, we'll bring these to the next Exploratory. We'll bring you a sheet of paper with these types of markings on it. Now, the next Exploratory is a week from Saturday at 10 o'clock. Right and I will remember--10 o'clock I remember. For some reason I didn't remember this one. And then you could not only do these blocks for folds but you could also do them for faults. If we come down here again, you see here, and one of my students had done this, it's a normal fault. I'm pulling apart the blocks and the rocks move as a normal fault. So we'll bring you some models. The things to remember are faults and folds. You don't have to be extravagant with all the details. Normal faults are quite common in West Virginia. The faults that are reverse faults or thrust faults are usually hidden in West Virginia. But the folds are everywhere in the eastern one-third of the state. In the western one-third of the state, they're there but they're very subtle.

Deb: We also said that unconformity is just about as technical as they needed to get for the angular unconformities, the disconformities.

Dr. Bob: It's a break in the rock record. And sometimes more things happen, sometimes fewer things happen, that the unconformities indicate a loss of deposition, constant deposition.

So, with that context, those textbooks will be coming. Keep watching the videos and do the reading for next week. We'll catch up on the other reading. When you do get the textbooks, when you get it next week, do the reading for the next show. And the next show will be in three weeks and we'll see you at the Exploratory.

Deb: And hopefully at the conference.

Dr. Bob: And hopefully at the conference, indeed. We'll remind you again of that during the Exploratory. We'll also find out if all the books came when we meet you at the Exploratory. So until our Exploratory which is eight days or so from now at 10 o'clock in the morning the same places you've been to, this is for Deb, myself Bob, and Tom who's waiting near the phone lines. Take care and keep looking at those rocks, and remember that everyday is a great day for a field trip! See ya soon!

WVGES Education Specialist, Tom Repine (repine@wvgs.wvnet.edu)

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