Geoscience Education in the Mountain State:
CATS Geology Telecourse, Fall 1998,
Show 3 Transcript

CATS Telecourse Broadcast
Geology 290
October 22, 1998

Dr. Bob: Good evening. Welcome to CATS Geology. Deb and I were just talking about how much interaction occurs between scientific disciplines. We rely quite a bit on what other scientists and other sciences have set forth. Biologists speak to issues of evolution. There are paleontologists, whether they're working with paleo plants or paleo critters, invertebrates or vertebrates, spend a great deal of time and study much as a biologist would. Those who are in the chemical aspects of minerals and rocks and chemical changes spend a great deal of time with chemistry.

Deb: They use mass specs just like chemists would.

Dr. Bob: As a matter of fact, the mass spectrometer is a really critical instrument with respect to radiometric dating. That is, the mass of the individual isotopes of elements is the critical component for making measurements. And a great deal of this is predicated on the fact that what the physicists have set forth we geologists adopt. We do not generally go back to tweak or reestablish. A good example is absolute dating and half life of certain elements. One of the participants sent in a question asking, "How do physicists really know what the half life of an isotope or element is?"

Deb: Right. You can't wait around for 4.5 billion years for something to undergo half its decay.

Dr. Bob: Even with radiocarbon, carbon 14 isotope! You can't sit around for thousands of years to do it. And the specifics? I'd have to admit this question came to me very late. I don't know the specific answer and this intrigues me now! I'm going to look it up. But I suspect it has to do with using the mass spectroscope and looking at the radiogenic elements and trying to purify them and obtaining measurements of the radiogenic daughters. It's important for you to remember that all this stuff with radioactivity is an average. We can't line up each atom and sit and watch it and say when it's going to decay. Half-life is based on the average of the elements that are incorporated in the rocks and minerals. So, we will investigate and share that with you the next time we meet. What other sorts of things have come up in questions?

Deb: One of the things that came across in the video that's always asked by my students is, "Well how do we know that the Earth wasn't created 4,004 years ago as Bishop Usher said?" In the video they used an argument that was really interesting and that I really never heard anyone use before--that was the biological argument that the bushy cone pines are 8,000 years old and we can get that from tree ring dating.

Dr. Bob: Tree ring dating is something that the botanists had set forth. And there are a number of geologic sites where we actually core the trees to find the time of the event. For example, a mud slide occurs and then the vegetation comes up and we core the largest trees and we find that those trees are at least 80 years old. We know then that that mud slide must be older than 80 years. It cannot be younger, then. And in most cases that's the way we use tree ring dating.

Deb: This whole tree ring dating is a science. It is used extensively in archeology. When they take a pole or something that was used to build a hut, they can core into it, measure the tree rings, and tell by the width of the ring whether it was a good growth year or a poor growth year. And if you compare those sequence of events to other trees, then you know exactly in time when that tree was cut. And you can match that sequence up and then determine the age that that hut was built.

Dr. Bob: In the southwestern United States, we can look at times when the climates were different. That is, the growth of tree rings today of that particular species is not going to reflect the growth 2,000 years ago or whenever. Scientists have taken tree ring patterns and overlapped them so that they have a long continuous record without having one single tree of any particular age. They have melded together, if you will, the evidence f rom the current to the past.

Deb: I think its called dendrochronology.

Dr. Bob: Dendrochronology is the exact name, that's correct. In a geologic sense, we can do the same thing looking at the layers of sediments called "varves." We now call varves rhythmites. Because there is a rhythm to the deposition--thin and fine grained in winter when the ice has covered the lake, and then in the summer it's thick and coarse grained because the ice is no longer present and water and rainfall is washing material in. And what we get in this case too is a long-term history of events over a very long time. What other sorts of questions had come up?

Deb: Well, "How do you demonstrate half lives in the classroom?" It's really a difficult thing for kids to understand because they say, "OK, you have this whole unit and if you cut it in half you have half." They get that far and they understand that. But then for some reason after that it becomes confusing. I'm not sure why they can't see that the half is cut into a half and so it's a quarter. They think: one half life, half of it's gone; second half of it's life, the rest of its gone. And so they have a real difficult time understanding this whole process. Why isn't this second half gone after the second half life?

To demonstrate that in the classroom, what we typically do is take a shoebox. You can either use pennies with heads and tails or you can use M&M's or Skittles that have a little mark on one side. You shake them up and you open the box and anything that heads up or the little "S" on a Skittle or an "M" on an M&M you take out. And then you write that number down. And then you shake the box again and you set it down and you look in. And you again take everything with heads or S's or M's out. You write that number down. You shake it up again and you keep doing this. Then you graph that curve. And if you start out with a large enough sample, say 100 M&M's, then it works out to about relatively a good model of half lives. Statistically speaking you have a 50-50 chance of it turning over.

Dr. Bob: But of course, if you feed them all that sugar, by the end of the class period you've got them wound up.

Deb: The secret is do not eat the sample.

Dr. Bob: It's a statistical sample. On the overhead here, I have quickly drawn as if we could line up the atoms. Of course the atoms don't show. They're wee little things. But shoulder to shoulder they go between these boundaries. And in the first half life, one half of all of them decay. And the other half remains. If we were to speak of this as if we were watching it happen, we have to sort it out again. That's what you do in the shoebox. You take the ones that decayed. If you use heads with the pennies, you put them all over here, and shake and then you pull put the ones that are tails. Be consistent. And the next time, you see half of what remains decays again and the second half life. And in this way we continue on so that after the second half life, three quarters of all the radioactive atoms have decayed and one quarter remains. And the graph is pretty good. Now how many pennies do you want to put in the box?

Deb: We typically start with 100.You want to challenge them with the graph. You certainly don't want low numbers. You want these students to be working with large enough numbers where it makes sense.

Dr. Bob: Speaking of half life and the duration of half life, helium three--H₃--has a half life of 14 days. That's real brief! We could actually measure that one! carbon 14 has a half life of about 5,600-some years. It doesn't take too many half lives to transpire before you run out of the ability to measure what's left. And that then becomes the limiting use of radiometric dating. Since it has a half life of just under 5,700 years, we can only go back reasonably about 30,000 years. There are some enhanced methods that speak to reasonable dates of 50,000 even 60,000. But they're not repeatable to the extent of real confidence levels.

Deb: There's no sample left to measure?

Dr. Bob: That's right. You're talking, after you get to the tenth half life, there's just not much material left to measure. In order to establish the baseline data of something that is radiocarbon dead, we can take a piece of coal from West Virginia. The age of the coal we know from other techniques, not carbon 14 but other techniques, to be something in the neighborhood of 300 million years. Students may ask if this means that the piece of coal from West Virginia has nothing radioactive in it at all? We say no, we're talking about carbon isotopes. And the specific carbon isotope that's radioactive, that one is gone. But there may be other isotopes that are naturally radioactive, especially in the uranium family and the radiogenic daughters from the uranium family, that may still be present. So that if the teacher had a Geiger counter in the room and attempted to use that, just in case there's a blip on the Geiger counter, you have the answer and the response. That's not carbon, that's something else, because the carbon is dead. So that when we talk about the fact--well, how do we know about this 300 and some million years, that we have found in West Virginia, Kentucky, and surrounding areas where there are the same age deposits we have found in an ash fall? One of the radiometric dates we have already talked about is carbon 14. Another one is potassium argon. At normal temperatures and pressures, argon is a gas.

Deb: The gas must be trapped in the rock? Is that how they're able to find it?

Dr. Bob: Exactly. So that the gas is trapped in the rock! But, if the rock looks like this igneous rock, it's got a lot of holes in it. Which means the gas is gone. This would not be a real great candidate for dating by the potassium argon method. Overall, the potassium argon method is excellent for igneous rocks. It is the potassium argon date that helps date igneous rocks like basalt and volcanic ash. The potassium argon date of the volcanic ash that fell in West Virginia is 312 million years before present. This is often abbreviated as "312 million years, pb." By the way, present was taken as 1950 because it was around that time that physicists put together a good understanding of radiometric dating. And geologists had used that understanding to develop radiometric age dating. So, we actually do know the absolute age of some of the rocks associated with the coals in West Virginia.

Deb: So if there is ash in West Virginia, were there volcanoes in West Virginia?

Dr. Bob: When we talked about plate tectonics, we talked about the fact that Europe and Africa and North America were colliding. Early on in the collision, there were episodes of island arcs that must have formed east of us.

Deb: Did the size of the eruption also have to do with the amount of ash that was deposited? Say, if all the other eruptions were fairly small, maybe the ash didn't blow this way?

Dr. Bob: Yes. The eruptions that we tend to think of these days are the ones that have occurred within the past 20 years. Mount St. Helens was a good size eruption but certainly not historically in this century the largest. But Mount Pinatubo was really something. That was a tremendous amount of ash but the ash is only in a local region. So really big volcanic eruptions will produce ash that will have a much greater distribution--the very fine powdered material of Paraketim in Mexico, or Pinatubo in the Philippines. These violent volcanoes occur at convergent boundaries: oceanic-oceanic or oceanic-continental. Those are the only ones that put a great deal of ash very, very high, ten's of thousands of feet into the atmosphere. It then gets distributed in thin bands all the way around the globe by the high-level air currents. Though it isn't of great density, the volcanic ash in the bands can have an effect on the surface of the Earth. Measurements taken in Hawaii show that the ash in the atmosphere can cool the surface a degree or more.

Deb: A convergent boundary is one where you've got one plate subducting underneath the other.

Dr. Bob: Let's talk about atoms and elements. Deb, you taught at how many different levels?

Deb: I taught 8th grade, 9th grade, 10th grade, 11th grade, and 12th grade.

Dr. Bob: I've always found that when I get out into the classroom with kids, some kids have parents at home who talk about these things and promote science reading. They have a real understanding of the atom. What do you find is the simplest model of the atom that youngsters can understand and live with?

Deb: Well, in terms of demonstrating what the basic, say, hydrogen atom looks like?

Dr. Bob: The parts. Right.

Deb: Usually, spheres. Usually taking spheres or balls. Some people use gumdrops because they work well with toothpicks. They're gummy. Kids like to play with sugar. They can eat it afterwards.

Dr. Bob: The styrofoam spheres that I am using here are getting to be more and more expensive. Let's put a couple styrofoam spheres up on the overhead. What we're using to put these together are just short segments of pipe cleaners. These spheres are an inch and a half in diameter. A dozen or so of them might cost a buck and a half these days.

Deb: You can buy ready-made models but it's an expensive proposition. And when you're on a shoestring budget, like I always was, it wasn't feasible for me to buy expensive atomic models. So this was the best thing because it was readily handy.

Dr. Bob: What's really difficult is cutting the pipe cleaners! You want a pair of shears, very strong shears, because there is a wire in here that your scissors in the school classroom are not going to hack through.

Deb: Actually, you'd be surprised how many teachers have wire cutters.

Dr. Bob: It's needed for this I'll tell you. What you may do is a game that I play in the younger grades. I give them three spheres and ask them to put them together any way you want to. Have them work in groups. I've found that not until you're about in fourth grade can you really work in groups and share the number of spheres that are at a given table. Some people will come up with that type of figure, others will have this, and they'll put them at angles. And some will make them look like Mickey Mouse ears and that sort of thing. Play around with it.

I then ask them to just hold it up in the group so that all can see. I say, of all of those that are being held up, which group's has the spheres where the centers are as closely packed as possible without squishing the styrofoam? And they'll look around and point to the one that looks like this. And then without asking, they all start to put it together like that.

And the next episode is to give them four spheres. And then again they may make poodles but then I ask them again to hold it up and I say, in all these models in which model are all four closely packed? You're going to get some folks that are going to get it in a form of a square. And the beauty about this is nothing is wrong. It's just different, that's all. Others are going to offset them like this. Still others are going to put this one on top and therefore if you rotate it there's a symmetry isn't there? No matter how I try to put this flat on the table, there's the same symmetry. And of course, they say, I know what you're going to ask. In which one are the centers the closest spaced? Now they will point to this one, but I'll have you know that it was not until a Cray computer, a real number crunching computer was available that mathematicians had not been able to prove that this is the best packing method to get the centers that close. What they have often related it to is the packing of oranges and shipping them from Florida to the stores in the cooler climates. What is the most reasonable way of doing this in space and volume? It's the orange packing activity! But it just hasn't been proven until the episode of working with the Cray computer.

Well, in working with these types we have not yet talked about the subatomic particles. We're simply talking about the spheres and shape. And somebody's gonna say, "Are you talking about atoms?" And in the younger grades I said, "Nope, just talking about spheres." So we have done this now. If you are going to do this, you do it with three and then with four and the next one is with six. That's all we're going to do tonight. Without belaboring the issue, four spheres, I have created a situation where the centers of the spheres have created a square geometric form. What you will find is that when these come together, this is a very important bonding unit. Ninety degrees between the two and any two adjacent that bond has to be 90 degrees right at the point of contact. Some of them may have distorted a bit as a rhombehedron form. But in any case, the addition of two additional spheres suggest that one could fit up there very nicely. And that kind of looks like a pyramid. Notice that this doesn't have the same symmetry as the three spheres. I keep rolling it around. You can find flat surfaces but they're going to look dramatically different. And the final sphere, the sixth sphere, fits in right there. Now this model has interesting symmetry, as I pointed here under the overhead, or rotate it like this, there's a good symmetry. And then if I rotate it like this, there's a good symmetry. And it continues all the way around. Now we have a number of corners and we have a number of faces to the model. So this is the next one. And you can still do this with 3rd and 4th graders. When we had three spheres, that was a very trivial triangle. It had three corners and faces that were just sitting there in one plane although it had a third dimension due to the diameter of the sphere. When we went to four spheres, how many corners did it have? Four. How many faces does it have? Four. And this is known as a tetra- (and we borrowed that because it means four) hedron (and that means faces). The six is kind of an interesting little rascal. When you put the six spheres together, how many faces are you going to get? How many corners, first of all? You have six corners, right?

Deb: Looks like two tetrahedrons.

Dr. Bob: Yeah, but when you think about this, one, two, three, four, five, six. But look at it real carefully now. Look at it in this way. One--this is the top--one, two, three, four on the top, and how many have to be on the bottom?

Deb: Four.

Dr. Bob: Four more. I flipped this over so there's eight faces. You have to work with folks very carefully on that. All of a sudden you say, "Oh, yeah!" if you hold it just that way and talk about a face here, two, three, and four and then the same number on the bottom. You have eight faces and that becomes known as...an octahedron. Because you had four. It looked like we were building it from an earlier model but it wasn't quite that way. So this is a system that you could use and something that you could use with the youngsters.

Now, since I didn't bring them out, let's see if we can do it. The odd numbers five and seven don't make any sense in nature for the building of the structure of minerals. But eight does. And how would you orient the eight spheres in space? The simplest model would be--you still have to have eight corners because you have eight spheres, and what would be the simplest model? Here's four. I took the critical one apart that held everything else together. Now there's the first four. Now where would you put the second four to make it the simplest model possible?

Deb: Plop them on top.

Dr. Bob: Put them right on top, yeah. And then the bonds have to be at the right angles. Now that, and what's the model?

Deb: Cube.

Dr. Bob: It's a cube! Yeah. Now, how many faces does a cube have? This is tricky, this is neat. How many faces does a cube have?

Deb: Six.

Dr. Bob: Six. The number of faces goes down. It diminishes simply because of the geometric form and shape. You can bring this out in 3rd or 4th grade. They can have a lot of fun. Then put them away and bring them out in 6th grade or 7th grade, two years later. And then start speaking to the issue that there's space in here. There's a void space. And would a sphere of this size, of the size of all the other ones, work in that void space easily? Doesn't look like it. Doesn't look like it at all. It has to be a bit smaller. And then you can start talking about the way that compounds are made. Because by that time they're gonna say, "Yes, these are spheres but they're really atoms." We tend to use the Bohr model of the atom. There's a nice one. And in today's classroom, how do you describe the Bohr atom and what simple parts do you talk about?

Deb: We simply talk about a nucleus that contains a proton and a neutron. And an electron cloud that contains an electron. That's our basic structure of an atom.

Dr. Bob: OK. And within the electron cloud, are there always protons and neutrons?

Deb: In the electron cloud?

Dr. Bob: No, no, no. In the nucleus.

Deb: That was a trick question?

Dr. Bob: No, no, it wasn't. I was thinking ahead. The question was going to be, in the electron cloud, are electrons randomly located or are they in specific arrangements?

Deb: As student get older, they encounter energy levels. Then we talk about quantum distances from the nucleus. But in earlier grades, we simply talk about the electrons moving about in an electron cloud. Not so much in the orbit of, say, the planets around the sun. But, it's a hard thing for them to grasp because the pictures are always two-dimensional.

Dr. Bob: Yes, yes. What grade do you introduce the limiting number of electrons in the first energy level?

Deb: Well, you try sometimes unsuccessfully in--I've seen some people try it in 7th grade, but 9th grade is when I really try to start driving that point home. They really don't memorize the numbers. They don't really get a good grip on it until they get to chemistry. Tenth graders can deal with it a little bit, but the chemistry students seem to get it.

Dr. Bob: You know, there's nothing wrong with that. Let's relate that to metamorphic rocks. I have been in classes a long, long time and working with different age levels. I don't think youngsters under 4th grade really grasp what metamorphic rocks are. You tell them the rocks are cooked and move ahead. They look different to be sure, but to change and alter--they really don't grasp that. And I'd say, OK, no matter.

Now, back to electrons. When we do get to 9th and 10th grade and start talking about the electrons. Do you call this the orbit? Or the shell?

Deb: You'd call it a shell.

Dr. Bob: A shell, OK. Do you give a letter designation to that?

Deb: No. Actually the chemistry students will get letter designations, but for the youngsters we just have them remember how many electrons will go in that first shell--two go in the first and eight in the second.

Dr. Bob: So we have two here in shell number one and in shell number two, we have eight. And we start building that way. OK. And in our nucleus, what has to be there at all times?

Deb: A proton.

Dr. Bob: And when do you introduce charge on these particles?

Deb: Right away.

Dr. Bob: So every proton has a charge of plus 1. Every electron has a charge of?

Deb: Minus 1.

Dr. Bob: Minus 1. Every neutron?

Deb: Has a neutral charge.

Dr. Bob: Neutral charge, none.

Deb: You say plus over minus.

Dr. Bob: OK, like this?

Deb: Yeah.

Dr. Bob: OK. It's a neutral charge. Now with respect to the mass that it adds, we have rather arbitrarily defined things, haven't we? And which ones have real mass in the atom?

Deb: The neutron and the proton.

Dr. Bob: OK. The neutron and the proton provide the real mass. What is the figure? I think it's 1,800 and some electrons are equivalent to one atom mass unit. That's a lot!

Deb: Oh yeah. It's like .0009 atomic mass units as an electron.

Dr. Bob: Somebody's goning to say whoever measured the mass of an electron? Well, we could do that as we split particles and so forth. But this model becomes very, very useful then, the Bohr model. And models are real valuable in analyzing things. Well, in geology we can spend a good bit of time looking at hydrogen. Now, in the chemistry you put the atomic number where? In the upper left hand or the upper right hand corner? Do you have a specific designation and location?

Deb: The mass number goes in the upper left. It varies.

Dr. Bob: Let take a closer look at hydrogen. There are three isotopes of hydrogen. Hydrogen 1, hydrogen 2, and hydrogen 3. The reason I'm spending this couple of minutes is that hydrogen 3 is naturally radioactive. It's a very brief half life--14 days. But it is naturally radioactive. And how does the model look for each one? Well, there's one electron. And in hydrogen 1, there has to be a balance in neutrality--one proton. In order for these to be isotopes, we recall how do we get mass without changing the charge? Add neutrons. So, in hydrogen 3, there is still one electron, still one proton. But now to get the mass of three, we have to add two neutrons. So that the mass changes in each of these.

Deb: The important thing to remember is that the atomic number never changes. The number of protons in the nucleus remains the same. Even if it is a different isotope.

Dr. Bob: Right. And we are going through this because isotopes are very, very important in geology. Now, different isotopes have a dramatically different frequency in nature. And when you see the mass provided on the chart or in a book, it always has decimal points. And what does that mean? That's looking at statistically how many different isotopes there are and that's why there's a decimal point. It's an average, if you will...

Deb: Average of their frequency and abundance in nature.

Dr. Bob: Yeah, so that if an element had no isotopes, it would be a whole number. It has to be because it can't have any parts of electrons and that sort of thing and neutrons and protons. Hydrogen is very important because it combines with the other very important rascal--oxygen. And oxygen is very, very interesting. Because if you talk to kids and you've introduced something to them, when they think of oxygen, what state of matter do they think of?

Deb: Gaseous.

Dr. Bob: Gaseous. And it's usually made up of two oxygen together so they would always talk or think of this as being O₂ and then you give them this symbol too, the little gas symbol...

Deb: "G" in parentheses.

Dr. Bob: Oh, OK. As a gas.

Deb: In parentheses.

Dr. Bob: That's right. So there's oxygen as a gas. Now, in earth science what we find is that the Earth's structure is a framework of oxygen but not as a gas linked together with other elements to form solids. So when you have them get out on the playground and jump up and down, they're jumping on a framework of oxygen. And that's really, at first glance, hard to understand. Why should that be? And the reason is, what is this structure again?

Deb: Tetrahedron.

Dr. Bob: Tetrahedron. It had four sides. And it had four spheres. The great abundance of oxygen creates this as a model in the structure of the Earth. And the wee little bitty space in the center--some other element is going to have to fit in there to hold them together. And it turns out to be silicon. And some cases aluminum. So that the mineral structure of the rocks of the crust of the Earth turns out to be the silicon-oxygen. The silicate minerals are so very abundant down deeper in the crust of the Earth. This is where you talk about the structure of oxygen being critical. And that's something that they'll have to take on faith. The students can't tear apart the rocks and the minerals to see the oxygen and silica. But a chemist could. In effect, that's exactly what we do with minerals. We tear them apart if we don't know what their composition is. We tear them apart and try to identify each of the elements within there.

Deb: So all of this putting together of atoms and making these shapes are related somehow to the minerals that we're going to be looking at or talking about?

Dr. Bob: Exactly. It would really be nice if the minerals could be modeled like this but unfortunately it doesn't work that way. The mineral structures are very complex. There is one mineral structure that is simple, and they talk about it in your text. But it happens to be a mineral that's not all that abundant on Earth, but we make very important use of it. That mineral is a combination of two elements, sodium and chlorine. Youngsters know it as salt. Geologists recognized this as a mineral, and the mineral name is halite. You know, it's interesting when we talk about a person who isn't worth their salt. That comes from the fact that salt was a very important commodity. And the Roman legionnaires were paid in salt.

Deb: Well, Charleston is there because of the salt industry.

Dr. Bob: That's right. Charleston, West Virginia, was a location where there were some natural seeps of the halite or halite dissolved in water, which we call a brine. Halite plus water equals brine. And a sequence of rocks well below the surface of West Virginia had these brines in them. Some folk came to West Virginia to drill for these. In some locations, this material actually seeped out of the rocks on the ground. Early settlers knew them as salt licks. Animals came to these areas. Geologists sometimes find the bones of many old animals at such locations, even from as far back as glacial times. So a salt lick was very important. And which president was one of the first to examine the bones? He was a president who was always tinkering, always inventing things. He invented the dumbwaiter. Yes, he invented the dumbwaiter. Thomas Jefferson! He spent a lot of time looking at bones from salt licks in Kentucky and West Virginia.

Well back to the drilling. When they drilled for the brine in West Virginia, what did they find? They got some brine but what else did they find?

Deb: They got gas.

Dr. Bob: They got gas and this black sticky, black stuff that they didn't want.

Deb: It was an accident.

Dr. Bob: It was an accident. They were looking for brine! Why did they need brine in the revolutionary days?

Deb: Preservation.

Dr. Bob: For preservation. The meat would go bad. Now it's interesting there's another way to preserve although this is not the best way. But if you take a side of beef and you put it in a bog, in a peat bog, as early Native Americans did, thousands of years ago...

Deb: Appetizing.

Dr. Bob: Yeah, it's not real appetizing but it didn't spoil in the bog because the bog was oxygen deficit. It didn't get putrid. It didn't get destroyed. So the early, early, early Americans stuck it in the bog. But later, they put it in a brine to pickle it or otherwise preserve it.

Anyhow, instead of finding brine, they did find some brine, but they also found natural gas and oil. And that's what started the oil and gas industry in West Virginia.

We are now at a good part to take a break. We do have one correction from the last time when we were talking about the gaining and losing of electrons. The gain or the loss of electrons is very important. First of all, it changes the element to an ion. We've talked about isotopes and elements as being neutral. Now we're introducing ions. And if an ion is created by gaining an electron, what is its charge? Oxidation is the loss of one or more electrons. Reduction is the gaining of one or more electrons. And what I used was the situation of iron.

Deb: Yes, that's more of the classic oxidation-reduction.

Dr. Bob: It's a classic one for oxidation-reduction. OK. And in iron we have one more electron in the ferrous state and it is the reduced state of iron. When we lose an extra electron, that becomes the ferric state. Don't worry about this now, but it clarifies our earlier discussion. We're not really goning to go much further. We touch on it a bit in weathering, about ions and so forth. But the really critical factor is in isotopes in geology--isotopes have different mass. And in nature, if those different mass units start separating, we can use isotopes to trace things and to reconstruct past events.

While we take our break, information about reading assignments and the upcoming activities will be on the screen. Let me review that information briefly for you:

For November 12th, the next live broadcast, you are to watch the Earth Revealed series; read chapters 13, 16, 17, and 20 in the text; and then continue with the Earth Revealed quizzes.

Then for December 3rd, watch the last of the Earth Revealed series; read the last three chapters of the text; and complete the quizzes.

In the original syllabus we talked about two tests. We're not going to do that. We're only going to have one test. And the one test is going to be distributed so you will have it no later then the November 12th meeting. Many of you at the Exploratories will have it November 7th, a couple of days early. It's totally a take-home test. One test. It will not be due back until the classroom meeting December 3rd. It will be a mix of some multiple choice and some short answers and something else I'll introduce shortly that you can start working on real soon.

So, let us now take a break. See you in about seven minutes!

(BREAK)

Dr. Bob: We are back. Some of you obtained a letter from the Extended Learning Office with respect to how your registration needs to be completed. There is a toll-free number on your letter. Call it and ask for Becky if you have any questions. She is really a gem. No pun intended since we are going to talking about minerals in a few seconds. But she is an excellent resource person. She has attempted to write in that memo everything that you need to do. The majority of the people in the class had been recent enrollees in courses at WVU so there was no problem with their particular registration. A few of you, though, obtained letters. If you have any questions call Becky. If you want to talk to one of us first, call Tom or myself, but Becky is the one that knows exactly your individual needs with respect to the registration.

We have decided, with pressure from the good folks down in Upshur County, that we going to have an extra field trip. It's totally optional in the context. If you've been to the first three you don't have to make the extra field trip. The extra field trip will be Saturday, November 14th. We will start at 10 o'clock and end at a reasonable time so that you can travel back. We'll start at the West Virginia Wildlife Center just south of Buckhannon. And we'll give you more information at the November 7th Exploratory. We're going to look at the rocks and the topography of the area and specifically the natural bridges in Upshur County. We have two counties in West Virginia where we have natural bridges--Upshur County and we also have natural bridges near Big Bend in Roane County. We will also see some other sites in the greater Buckhannon area. So that is going to be Saturday, November 14th, rain or shine, but it is optional. You don't have to be there.

One other aspect and I'll mention it now that I do have one component of the take-home test that you can start working on now. What I want you to do is to devise a unit for your particular setting. You can change it if you want to. Grade, location, the equipment you have, and so forth. And then you're also going to list materials. Even if you don't have them. What materials would you put together? You're also going to include identification of the West Virginia IGO's. And then you're going to also tell me what the assessment is, how you're going to work with these youngsters. The unit will be one week in duration. Assume you're going to have five class days. Some of you have 50 minutes and some might have 90 minutes in a block-type session. You tell us what time you have and what you plan to do. The topics are these, and you are to choose just from these two:

1. Plate tectonics and with how it affected West Virginia (How West Virginia Got It's Mountains)

or

2. The topic of mountains and West Virginia (Is West Virginia the Mountain State?)

You can put other titles to them, that's fine. But in this context you have two items to work with. So as I often tell folks, sleep on it a couple of nights. Think about this. You have the basic topic and the information is there for you not only on the videos that you saw in Earth Revealed but also your textbook. These in fact are chapter titles. The West Virginia components relate to some of the geology of West Virginia that we talked about in the earlier episodes on air. The mountain making, the folding of rocks, the faulting of rocks, and you can incorporate materials out of the textbook, the basics of plate tectonics. It is yours to do with as you will but just devise a unit and how you would assess the students-- what they would be doing in the time they have on the task of understanding this. And if you want to run to two weeks, that's fine. But you have to have a minimum of a week within the context of the time you have available. I'll bring this back up again. It will also be in writing when you get it November 7th. But this is something you can start working on. This will reflect 25 points. One quarter of the 100-point test. This will also be due on December 3rd but if you want to get it in earlier that would be fine. No problems at all in getting that in at an earlier time.

Now what we would like to move on to now is to talk about Earth materials. The text does a very nice job of some of the details. What I would like to do from time to time is intersperse the West Virginia focus on the minerals. One thing I do with youngsters is I bring a little plastic bag and I put out some materials. Here's material, and they'll say these are all minerals because that's what we're studying and we're at that point in the text. But what I would give to them if we had enough samples are some different things. OK. These all look a bit different. And the number is just going to be basically what you have available. Different looking things. Different colors, different shapes, sizes, and what I do with them in playing a game is to have all the ways in which they're different. Use your imagination. And then working in tables, maybe six tables around the room, work in a sort of a double jeopardy. Each table in sequence. I number the tables and then I scramble the numbers and I pick the numbers out. Then I put them back in again and I jumble them up and we see if each table can identify something different of all the materials. And what I might give them additionally, if it's in older grades, is weak hydrochloric acid, the magic elixir. If it's younger grades, I might give them a little bit of vinegar. The vinegar smells bad, they're not likely to drink it, and we give them appropriate warnings in any event. Of course what they start pointing out is some are black, some are gold, some, if you take it, you can even write with it. It's very soft. Others are so hard that all it would do would put a dent in the paper or maybe even tear the paper. This one doesn't do any mark. But if I give them a piece of porcelain, that we call a streak plate, then some of these leave marks. The point is that these are all in the classification of minerals, the building blocks of rocks. Minerals have certain components to the definition. The components include the following:

They have a chemistry. However, in geology we allow a range of (1) chemical composition. We do not demand the preciseness that a chemist does. So it can have a range of chemical composition.

And then there's also an (2) internal arrangement of atoms--all the participating atoms in internal arrangement.

We also say that it's (3) naturally occurring. It is not created. And one of the items then that really becomes a challenge to the youngsters to say is glass a mineral. And the answer would be: it's not natural. So it's not strictly speaking a mineral.

And then, now this one is a bit of a--we hem and haw about this one, we say that it's (4) inorganic. And by today's standards that's not exactly true. Because we have added in as a result of years of study of coal that we talk about organic materials as minerals. The coal of minerals, as a result of combinations of other atoms with carbon. So we have changed that a bit and we do talk about a very limited number of organic minerals when studying coal. But we do not in any way, shape, or form give into that vast array of compounds that the chemist would put under the title of organic chemistry.

So we look at things a little bit differently than chemists in a sense that we are not always resigned to list the relative percent of each of the participating elements. For example, water. Now we usually see water written that way: H₂O. But as a geologist, I like to think of water as HOH. Because it dissociates. We usually draw it like this with the little arrow and it goes into the hydrogen ion plus hydroxyl ion. And the reason I like to write this as HOH is to continue to show the students that this is exactly what happens. Water is an extremely important agent with respect to chemical weathering because water breaks up, even though it's a very modest amount, but it does start to break up. And this hydrogen ion can start tearing minerals apart. It's presence is going to promote the chemical weathering of a vast array of minerals. Very important situation. So from time to time then, I will write things a little bit differently than the chemist might, and that's OK. We're looking at things in the natural environment. And in the natural environment, the purity is not always there. That's why we speak about the range of chemical composition. We couldn't possibly break everything down. We now have almost 3,000 minerals, but the vast majority of them are so rare. The common minerals, if you know about 12 to 16 important common minerals, you'll be able to cover almost every eventuality, except for the youngster that likes to collect pretty minerals. And then you just throw up your hands and say that's in the realm of the other 2,980 that I don't happen to know. I was caught in that situation the other day having try to identify minerals. I'd say whoa, I just don't do this on a regular basis. The mineral or gem collector might do it. Someone working museums specifically with minerals. So, well, that's not so bad. There are some common minerals that we need to know about.

Then there are many others that we usually test on like pyrite--that's pretty common. But it's not one of the real common minerals. But the two that I had out before, the dark mica, the black mica that's opaque, and the translucent or transparent mica. Both of these are mica. And we find both of these in the rocks in West Virginia, broken up into small pieces, brought down from rivers a long time ago, and incorporated in the rocks. These are little black specks that glisten. They're not as common but we do see some biotite. This is very common in our sandstones in West Virginia and it is muscovite, broken up as so many little pieces they look like little mirrors. When you take the rocks in West Virginia and the grain size, a reasonable grain size, and you play them against the sunlight or an overhead light, you see the glistening. And that quite often is little flakes of muscovite that have been deposited along with the other minerals in the sandstones.

So the minerals are critical components, but we need to move beyond the minerals and we're going to do so without spending a great deal of time, as we would in the laboratory, on the identification of minerals. The text speaks to that issue. You usually have an acid bottle and a weak hydrochloric solution is all you need for the upper grades. The chemistry lab certainly has some hydrochloric acid--five percent, 10 percent tops. And of course, always add acid to water when you mix it because the heat of formation, if you add drops of water to concentrated acid, explodes! It's a very, very dangerous situation. So always add the acid to the water and make up about a five or eight percent hydrochloric acid solution. Really very weak. And that will react with certain minerals. OK.

You'll also want a magnet. You'll also want a glass plate with the edges burnished so that the kids won't cut themselves or somehow protect the fingers and such from the edges of the glass plate. And a streak plate, a piece of white porcelain. Now you'll have to clean the streak plate from time to time. Earlier I was taking a mineral and writing with it. Well, the mineral was graphite. And then once youngsters find out that graphite colors a streak plate, they sit there and they just color the whole streak plate in. Or they might use pyrite or galena, some other metals. But these two minerals, this one is galena. It's not all that common but it's a very important mineral for lead. And this one is "fool's gold," by common name, or pyrite. OK. And this one happens to be, this square one, is halite. It's interesting if you bring in a container of salt and you have a hand magnifying glass--10 power or so. Spill out some salt. You'll see little chunks of salt that are cubes or little box-like forms. They all have good right angles where they broke. And that is an example of halite. And halite has an additional characterization and identification mode that if you touch your finger to your tongue back to the mineral and then put it back on your tongue it tastes salty. That's because we know this mineral as salt. But it turns out that all three of these minerals are not very abundant. As a matter of fact, in some of the rocks in West Virginia, you see a little bit of pyrite and it does cause problems in West Virginia. Because it is associated with coals and due to weathering, it creates an acid. And the acid mine drainage is a direct result of the combination of iron and sulfur, such as in pyrite breaking down and creating an acid condition in the water. But these aren't the common minerals.

The common minerals that we need to work with relate to the fact that we know of three types of rocks:

(1) Igneous--literally the word means "born of fire." And when we think of that, we're almost thinking of volcanoes. Now you say, there are no volcanoes in West Virginia. There's a volcano in West Virginia between Parkersburg and Clarksburg along Route 50 in North Bend State Park but it doesn't have anything to do with volcanoes. But we think now, even though our youngsters were not even born when Mount St. Helens erupted--as a matter of fact, some new hires in the teaching profession very soon will potentially not have been born when Mount St. Helens erupted in 1980. But in the United States, we've talked about this earlier when we talk about Hawaii or the Aleutian Islands, that's when we're really talking about volcanoes. And then from California north to British Columbia, we also find a string of volcanoes, the Cascades, in the United States. And some of the more famous ones, Mount St. Helens, because of the recent eruption; Mt. Rainier, because of its beauty and stature and that it rises so significantly relatively close to sea level. It's not that far inland. If you're in Seattle on a clear day--count your blessings, there aren't that many of them--but if you stand on the University of Washington campus and their big greenspace courtyard and you look to the east, there's Mt. Rainier with it's snow-capped peak. And you're standing at sea level with sailboats in the bay. Beautiful sight. And that's why Mt. Rainier looks so dramatic. Then of course, Crater Lake is another in the continental 48 as part of these Cascades where the general geography is not that unusual, such that a number of students would have heard of some of these mountains and realize them as volcanoes. But that's the born-of-fire igneous rocks.

And then following weathering of all types of rocks, individual grains may be moved by rivers, wind, glaciers, running water, moving water in forms along the beach as well as running down slope as rivers. And the individual particles may settle out to become the (2) sedimentary rocks. Or the chemical reactions provide for elements that are dissolved in water but later may come out through crystallization to create the types of sedimentary rocks that come out by chemical means. So of the sedimentary rocks, we are going to have two different types that we'll talk about in a moment.

And then all types of rocks can go through change. An important component with respect to what we are trying to get across in CATS science, coordinated and thematic science--we're always talking change. And this type of rock, (3) metamorphic--the change. Now, what rocks can be metamorphosed? Igneous can be metamorphosed. Sedimentary rocks can be metamorphosed. And metamorphic rocks can be metamorphosed. Sometimes you see this discussion in a grand circle in an attempt to show a rock cycle. I am not very fond of the rock cycle because it seems to demonstrate an irreversible pattern that exists always and everywhere and has throughout geologic time. Whereas, I suggest to you that this is a blending in cases. What is the difference between a rock that has been heated to such a temperature that it's not quite melted but add a little more heat and it's melted and that's the zone between metamorphism and igneous? What happens when sediments are put under a great thickness, tens of thousands of feet of sediment squeezing down? That's a lot of pressure. And it's close to metamorphism pressure but not exactly. It's causing liquids to be squeezed out of that stack of sediments. Gases have left earlier. The individual grains started impinging one on the other and they may in fact start dissolving at that pressure point. And then the dissolved mineral cements the two particles together. That's a process of change in sedimentary rocks. It's not really metamorphism but it's only a thin definition away. And then too, what about the organic materials--the accumulation of organic materials in swamps that we're so familiar with in West Virginia? The formation of coal. Is coal a sedimentary rock? Yes. Can coal be a metamorphic rock? Yes. In our background, we say yeah, I know the term for that--that particular district in Pennsylvania around Scranton and elsewhere we call the anthracite district. Anthracite is the metamorphic coal and the coal we have in West Virginia is not metamorphic. It's sedimentary. But I would suggest to you that maybe all coal could be thought of as varying stages of metamorphism--alteration by pressure and increased temperature as the material is buried deeply below the surface. If you wish and continue to use a rock cycle, just remember that the individual rock types are not exactly that straightforward.

Let's talk about sedimentary material. Two of the groups in the Exploratory have already worked on grain size. And that will, we'll discuss that in the final stop on November 7th. And that group will be the group up in the northern panhandle, at that Exploratory site. The sedimentary grains start out loose, and then through change that we call lithification, it becomes rock. Sometimes that lithification is totally due to pressure, especially if some of the components are sticky. And if they stick to each other, like clay minerals, eventually a rock can result. But for the most part, we look for a cement to put the particles together. And there are three cements: One is (1) rust. Now we have a mineral name for it. If it's still young, it's FEOOH. Some oxygen and some hydroxides. After a long time some of the cement may then alter to this ratio to FE₂O₃--called hematite.

The second cement is (2) calcium carbonate, CACO₃. In West Virginia, quite a number of rocks are cemented with the hemitite or the rust color, but calcium carbonate is also present. Three individual elements, calcium, carbon, and oxygen.

The third cementing agent is (3) silica, SIO₂, also called quartz. It's a tough old cement. You'd find the quartz cement at Seneca Rocks. That's why Seneca Rocks is such a tough old landscape form. Sometimes pieces fall off of it, but you don't see it dissolving away. Calcium carbonate, on the other hand, will dissolve in a weak acid, like rainfall. It takes time and lots of additional rainfall to dissolve but it will eventually dissolve away by chemical actions. We're going to mention that in a few moments.

So this is some of the basis for sedimentary rocks. And the critical sedimentary rocks in West Virginia are, extending down thousands of feet below the surface: sandstone, limestone, and siltstone (because it's a smaller particle size then sandstone), claystone (even smaller particle sizes), and also coal. So those are the sedimentary rocks. The really critical sedimentary rocks in West Virginia. Sometimes you see a combination of siltstone and claystone together where its very thinly bedded and it'll be the shale. You see, in parts in West Virginia, shale with silt and clay-size particles comprising thin beds. So that's the sedimentary rocks. Now the reason I've done that first is that there are so many in West Virginia.

What about the igneous rocks in West Virginia? Well, there are two types of igneous rocks:

(1) Intrusive--they formed below the surface. Magma came into the rocks and solidified there.

Or (2) extrusive--the material came out on the surface. Well, that's the volcanoes.

Well, what do we have in West Virginia. We don't have any volcanoes. We do have some ash layers. But if I took you to the rocks and said, "This is where the ash layer is," you'd say, "I don't see anything different in those rocks." And you'd be right because you'd have to work at it with a microscope and examine it in very minute detail. So in effect, in West Virginia, we don't have real good examples at all of extrusive igneous rocks. Intrusive igneous rocks we're pretty much short of too. However, if you go down to Apple Grove or if you're a caver and one wall in Cass Cave, you will find intrusive igneous rocks that you can put your hand on. You don't have to drill 15,000 feet to find it. They're right there in the cave and exposed by weathering near Apple Grove, West Virginia. Now, you say, Well how far would you have to go to find a volcano? Try Monterey, Virginia. You say, whoa, wait a minute, that's not far from West Virginia at all. It could have been us. There is a small hill and it's all black rock and it's a little volcanic cone that formed in the geologically recent time, the Cenozoic--a very recent one, just a couple of tens of millions of years old. Really bizarre. But nothing in West Virginia unfortunately. And at that time the wind was blowing, there's no cause to think that it was ash coming out of that at all.

Metamorphic rocks we find in West Virginia are in the eastern panhandle around Charles Town. Why is it out there? Again, because of plate tectonics. Because when Africa closed on North America, we find a rock that started out as a shale. Then it was metamorphosed probably continually and it passed through the slate and now it's phyllite. And it's called the Harper's Phyllite. So where would you go specifically? Harpers Ferry. When you're in Charles Town, the rocks look crooked but they're not quite yet metamorphic rocks. You have to go that extra seven miles, five miles or less down the road towards Harpers Ferry and that's where you see the phyllite. And then there was a sandstone that was metamorphosed and it is now a metaquartzite. So those are the metamorphic rocks in West Virginia. Now to be sure, there are a number of metamorphic rocks and perhaps igneous rocks in the basement, but we'd have to go down in some places 15,000 feet or more to get to the basement. So we can't ever see those.

We also can find igneous and metamorphic rocks in the gravels along the Ohio River. Because when the glaciers brought material down from Canada, then the glaciers melted and the material became pushed and eventually deposited along the banks of the Ohio River. So that's why I wanted those chapters on rocks. You have lots of detail to read but these are the ones of West Virginia.

Now what about weathering? The weathering is the alteration of rocks. It can be either (1) mechanical or it can be (2) chemical. The mechanical weathering breaks the particles up into smaller pieces but then can be chemically weathered. And as a result of all of this, the rocks in West Virginia yield to form soil. And soil is the realm of the soil scientists and agronomists. It is a reflection of all the weathering processes of all the rocks that are up the hill, or in the valley, or brought along in the river. So, we will emphasize soil again and the weathering as we pick up and use this as a bridge the next time we're on air.

For closure, I want to bring up again the fact that we're only going to have one test and you will obtain this test at the site of the Exploratory on November 7th. And then you will get additionally that information on November 12th. You'll have that at your site when you come to see our next on-air presentation. This is 25 percent of the test that you can start now. It's all going to be take-home test. Devise a unit, for 25 percent of the grade of the test, for the grade you want to use it for, your location, the equipment you have available. List the materials that you might have to purchase or acquire. Don't worry about the fact that you may not have them or it's not likely you'll have them by November 12th. OK. But that what you would need, and the identification of the West Virginia IGO's. How you're going to assess the students and put it for a block of time at least about a week and within the time frame you have to devote with your classroom to this particular science issue. And it would either be plate tectonics or mountains in West Virginia--your choice. And why I would urge you to start studying this is we're going to see you on air, of course, November 12th, but we're also going to see you November 7th. If you have some questions, hit us with them, ask us.

Additionally, a few of the folks have issues that must be worked with Becky Snyder or Sonya Belaire. The 1-800 number was included on the information which you received if you have a problem. And it's not a problem, per say. These folks will help you get it solved. It's just the variations on the theme. Perhaps you haven't been a student recently for the graduate program at WVU or one or two folks may never taken a graduate course at WVU. These are the types of things we need to work out. And because we only meet once every three weeks, we have extended this concern and have found out about it since our last timing, the details. So we'll work that all out.

In the meantime, for all of those who were able to make WVSTA, a fine time was had by all. As we start getting this break in weather, look for weathering by ice crystals. Look at the rocks! We'll see you at the Exploratory November 7th. Until then, take care. It's a great day for a field trip!

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

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