Geoscience Education in the Mountain State: CATS Applied Geology Telecourse, Spring 2000, Show 2 Transcript

CATS Telecourse
Applied Geology
February 8, 2000

Dr. Bob: (Joined in progress) In the first half before the break we have comments and considerations. We're going to talk a little bit about aspects of the course to pull that together. Then we'll talk about specific national parks, Crater Lake, Lassen Peak, Hawaii and Sunset Crater. Then we'll do a classroom type discussion as to compare and contrast Yellowstone and Hawaii for the classroom. We'll have a break and come back for Bryce, Zion, Carlsbad Caverns, Glacier National Park, and we've been trying to relocate a picture that we had found on the web site. We'll talk about that although we haven't been successful in finding that yet. Then, Cape Hatteras and we'll note that next week we're back on the air with another adjunct and we'll talk about fluids in motion, wind, ice, and water, and mass wasting and weathering. Especially as it relates to these national parks but really relates to all the national parks. It's especially the ones after the break. There will always be a bridge between what we're doing in the adjunct and what we're doing in the regular show.

Start out then with comments and considerations. We have some things to talk about with respect to the course. Would you take it away Deb?

Dr. Deb: Number 1, Tom wants me to announce that the last day to sign up for this course is today. Make sure you get that accomplished. If you are viewing the tape we need to have you registered by the end of the week. The is the drop dead date for registration, so get those registrations in.

In terms of the course itself we'd like you to take a look at the web site. I'm going to show you a couple of things that you might not be aware of. If you scan down the web site for WVGES you'll see a couple things here. One is that I'd like to clue you in to is the transcript. If you click on the transcript, that would be the last show's unedited and all it's grammatical mistakes and typos. The unedited transcripts, if you just want to look for a quiz question or the answer to something and you don't want to rifle through pages and pages of script, there is a shortcut for doing this. If you go to "edit" and go down to find in a page and click on that, you'll come up with a little screen. There you can type in, for example, the word bombs if you want to know what a bomb is then hit "find next" and it prompts up with the word and then it's in context and you can find it. Rather then trying to hunt and peck through pages and pages of text you can use the transcript this way and it's not quite so cumbersome. Make sure you do use that feature and make the transcripts work for you.

The other things is, make sure that you realize that we do not put the adjunct transcripts on there. If you're a 4 credit person and you're watching those adjunct shows make sure you take copious notes and you'll have to pay close attention. It's labor intensive to get these things on the site.

The other thing I'd like to point out is, you'll notice that we have the link here for the park geology or the tour of the national parks. All you have to do is go to the WVGES web site and click on that link and it will take you there. These are all of the sites that we were referring to last week and some of the sites we're referring to this week and some we won't get to. This is a really nice comprehensive page on park geology and virtually go around the United States here.

The other thing I'd like to point out is, if you go to volcanoes and you go to the Hawaiian Island Volcanoes National Park there is a link here under teacher feature that links you to "Volcano World." Go to "A Teacher's Guide to the Geology of Hawaii Volcanoes National Park." A nice teacher's guide. There are many, many things you can do in the classroom so I invite you to go into this web site and tool around and see what you can do. There are teaching and learning ideas for the kids. There are current eruptions. Instead of using the canned list in the textbooks, why not go to this web site, Volcano World, and plot some actual volcanoes that have been erupting within the last year or two. Then do a correlation between hot spots and plate boundaries. Whether they are convergent or divergent from this list instead of just the historic list. Just go through the Hawaiian Islands contact there on the National Park Service page.

The last thing we need to tell you about is right now the Discovery Channel has a couple of really nice programs. One of them is called "The Amazing Earth." It was broadcast last night but the next broadcast is February 13^th at 6 p.m., Sunday. The show focuses on volcanoes, earthquakes, and twisters. You might want to check that one out since it's pertinent to what we are talking about.

Dr. Bob: Just the other night, I believe on the Learning Channel, they had the Earth's deadliest volcanoes. They had some very good information on that too. The Learning Channel, the History Channel. Last night they talked about the construction of Hoover Dam (Boulder Dam). That's a great show. Keep looking for those types of programming.

Also, to repeat again, I do not intend to have tests per se in an end test for the semester. By the end of this week there will be Quiz #1. There will be four quizzes and Quiz #1 will be based on information from the national parks. We urge you to go back to the national parks on the web site, pick up some of that information, and also to review what we talk about during the course of the evening.

Let's get going. The first one is Crater Lake National Park in Oregon. Many pictures have been taken of this area. Until you get there you don't realize the blueness as to what it really is, a crater is the central core depression in the cone of a volcano. What we really have in Crater Lake is not a crater but a caldera, a collapse feature. The lake is very deep. It's over 1,900 feet deep and prominent is that region is Wizard Island. The water wasn't there initially. It has been captured literally because of the collapse, the caldera. Interestingly also, that the native peoples of the area always have stories about Mount Mazama. That was the name of the original peak which existed there before the great explosion and then the subsequent collapse of the caldera. There were two gods, the Klammath Indians had the two chiefs in their culture. One was the chief of the undersurface and that way Lao (sp.) and Lao was the chief at the site of this now Crater Lake. The other was the chief of the above ground world and that was Skell (sp.) and that is clearly taken to mean Mount Shasta. They battled with each other constantly. For historical context and anthropology and archeology, we can find very clearly, evidence of the Klammath Indians ancestors buried beneath the ash. The moccasins, tents and so forth and archeological sites buried beneath the ash of the eruption of Mount Mazama. The story continues that the two chiefs battled and battled and then to emphasize the point, push down Lao into his rightful home below the surface, deep below the surface. The suspicion is, that at the time the Native Americans were talking about eruptions that were contemporaneous between Mount Shasta and Mount Mazama. However, the real details from Mount Shasta do not support that. We do not find the absolute circumstances by dates at Mount Shasta. But it's an interesting, interesting component to think about. What I'm working with here is a book that we had told you about. If you are interested at all in travel and then the geology of the National Parks, this title "Geology of the National Parks" by Harris and Tuttle. An excellent book. I highly recommend it. If we teach a course in geology of the national parks at WVU it is this textbook that we will use. (Goes over some features in photos being shown.) The magma chamber is down below. We're talking several miles below. The scale, the thickness of the pen on the right, is about a mile. The cartoon shows the magma chamber at a depth of three miles. Is it exactly that? No. We don't know exactly where it is but it is at a greater depth then two to three miles. It shows here in cartoon fashion the great plume of dust that was emitted from that park when Mount Mazama blew. What happens next is that some of the magma starts to return back into the magma chamber and the column collapses. The column feeding and building the pressure beneath here. This is a volcano with a dasite or andosite. It is a higher silica, greater viscosity volcano so that the gasses became trapped. When you trap the gasses you create the potential for a very violent eruption. The material starts to drain back in and as the caldera collapses, there is an incredible amount of pyroclastic flows that race down the slopes of Mount Mazama. Any one in that area unfortunately at that particular time was at enormous risk. The arrows then suggest that a great deal of the magma is returning back to the magma chamber. Steam explosions, total collapse, the steam explosions are going to continue because as rainfall occurs, as snow melts, there's going to be the potential of the mixing of water down deep and then continued steam type eruptions. Then the final one, without worrying about the details of the words up there, that's the flows. In the caldera floor, Wizard Island is built. It's a cinder cone first and then the crater or the caldera, filled, and therefore created the lake and then it became an island. Wizard Island did not erupt through water. It erupted in the caldera and then the caldera filled. One other picture that needs to be shown to get an appreciation here. This is the extent across the United States with Crater Lake being down in the lower corner to demonstrate where the ash and the debris fell. We have a general term for that, the tefra (sp.) is ejected material of all sorts. This is an ash that can be very specifically can be found but notice that the main deposits, the principle deposits, are not across the entire United States. The prevailing wind direction apparently was on the sine wave coming from the southwest to the northeast at the time of the eruption so that British Columbia and Alberta, even Saskatchewan, Montana, Idaho, Washington, and Oregon. A very large area of northwestern United States was covered by material. Before I leave that point I want to emphasize again that we have a definition of the date of the eruption. How do we get that sort of thing? We're using the carbon-14 dating method. Volcanic ash? Why not the potassium argon dating method? Because that is method for volcanic material. The reason that we can use this is that it was so very recent and more importantly it buried pollen, organic material in lakes and ponds, and there are even some very, very precise statements as to when that eruption may have taken place. In general, you see statements as to the eruption about 7,000 years ago. In other cases you get another date that says 6845 years ago. Carbon-14 dating provides some very accurate....sometimes you'll see the 7,000 or 6,800 plus or minus 50 years. That suggests that the scientific reproducibility of that date has some variability based on taking the organic material, accumulating it, turning it into pure carbon and then finding out how much of the isotope remains. This is an approximation and yet it's one of the events that comes very, very close...probably there are those who believe that we have an absolute date on that within two or three years, not the 50 years. It is a fascinating situation. You can now drive the entire crater width. It's a very high lake in elevation so that the roads are often closed in winter. There are no permanent glaciers or ice masses that are glaciers on the flanks now. But when Mount Mazama stood at this site there were permanent glaciers there. Of course, it was also a mountain during the Pleistocene and therefore would have been expected to support glaciers when the climate was cooler. The composition, more andocitic but there's also some basalt. Lots of tuff. The tuff is quite often welded because it's still warm. Then we also talked about andocite. I used the term andocitic and it means that the chemical composition is andocite like and these of course were rocks that were first described in the Andes Mountains of South America. We talk of them as being intermediate. They're not mafic (low silica), they're not felsic (high silica) but andocite is in between. The material has come up from the subducted oceanic floor. Come up through the continental mass. Different elements have been added to it and the eruption is stratovolcano on the continental mass with the magma chamber that was formed then can obtain the materials and elements from the continental crust, which means the silica content increases but its not to a granitic or felsic type composition.

Dr. Deb: The U.S.G.S. web site compares several eruptions just so you have some kind of idea of how big Mazama's eruption actually was. We see the remnants of this caldera but if you put it in perspective to Mt. St. Helens you can see just how far the tefra or the pyroclastic debris that was extruded from the volcano actually went. Across the bottom is the distance in kilometers, over 1,000, whereas Mount St. Helens in the 1980 was just shy of 600 kilometers. If you look at where the line is on the vertical axis and that indicates the thickness of the tefra. That's compacted thicknesses.

Dr. Bob: You see that it's almost an exponential expression, the decrease in thickness away from the crater itself. All of them have that same pattern. The particle size was relatively similar. How do you get these anomalies? Well, we don't know the details of where they collected these, there just happens to be a lack of material here. Maybe the curve is more flat in general. Note also that they use a date of 8,800 years. Different resources, many of them have a range and yet there are many people who believe that we have a very, very precise age for that which is about a thousand years younger then they one they are showing. We did not have radiometric dating until 1950. Carbon-14 dating was one of the very early techniques that was used and employed. Those details we don't have for you as to why the variation.

That is a brief discussion of the details of Crater Lake. It is a site I'll be going to this coming June with Marion County teachers using their Eisenhower dollars going out to the Cascade area and we'll see Crater Lake up close and look for some of that information.

Prior to the eruption of Mount St. Helens, the last time an eruption on the adjacent 48 states have occurred was in the period between 1914 and 1921. That was in northern California. Northern California, Oregon, and Washington and up into British Columbia is all part of the Cascade range. This peak that we're speaking of also was part of the Cascade range and that is Lassen Peak. Deb, you've been to Lassen Peak, what sort of things are there when you saw it because the eruption was 80 years ago?

Dr. Deb: There are still many, many sulfur pots and hot springs associated with it. I was there before much of the park was opened due to the weather. A lot of the roads were still snowed in. I did get to see Bumpus Hell which is kind of an interesting area. The history goes that a fellow that was ranching up there fell through the crust of the mud into the hot boiling water and singed his leg and said his leg went to hell and did it again and actually lost his leg.

Dr. Bob: A slow learner, a steep learning curve.

Dr. Deb: It's an interesting park. I was actually there a long time ago so it was well before my interest in geology had developed. I was really a tourist. I was looking at the features from a great deal of ignorance. I would like to visit it again now knowing what I know.

Dr. Bob: One interesting aspect of this is to reflect again upon the nature of national parks in the United States. First of all, in 1907 this was identified as a national monument. Teddy Roosevelt and all presidents have the ability to name something a national monument. But only Congress can make it a national park. Then by 1916, Congress enacted it as a national park.

(Goes to a book) I'd like to show you a broad cross section and what we have here again is very similar. Stratovolcanoes, dacite composition (a special word suggesting that there's a different type of felspar), you getting more plagioclase felspar then orthoclase felspar. In a felsic composition you'd have far more orthoclase then plagioclase felspar. Orthoclase is a potassium felspar. Plagioclase is a sodium calcium felspar so your talking chemical composition. Dacite implies again that this is a more viscous material then say a basalt flow. The original mountain, and that had a name too, Mount Tehama, was the former crest. It broke down and what happened was a subsidiary peak, Lassen Peak, and that's what erupted in the 1914 and 1921 time frame. Lava was forthcoming. There's also basalt there and also ignimbrite (sp) a special word of explosive gas and ash together. Lassen Peak eruptions, a lot of talus and material moving down. I used a new word, ignimbrite. High temperature, gas, and ash. Sometimes you will see it referred to as a pyroclastic cloud. It really becomes a density cloud. It rolls down and it's very difficult to escape. Perhaps you have seen the photos of the great cloud that came off Mt. Pinatubo or Mt. Onzon (sp.). That was an excellent example. Also, one of these came down in Mt. Serat (sp.) and swept over the town of Plymouth in Mount Serat and actually destroyed it. Plymouth, the capitol of Mount Serat, is totally abandoned. Whenever these strike anyone there is at great risk.

Dr. Deb: Can you compare and contrast this with a nuee ardente (sp.) which you keep talking about?

Dr. Bob: It's really in that same category as to the nuee ardente (sp.). I don't know, for example, if there is a specific temperature relationship. The nuee ardente (sp.) is really a glowing cloud. Many, many hundreds degrees centigrade. These ignimbrites have gas and ash at a lower temperature then what you might find in some of the others. So, Lassen Peak's history is very much part of volcanic eruptions. I'd point out that in the United States, and now including Hawaii and Alaska, throughout this past century been rather blase about volcanic eruptions. It was something that happened to other people. It was not a problem that we had to deal with. In fact, we do have to deal with it and should look very carefully at all of the Cascades. It is true that when eruptions in the Valley of Ten Thousand Smokes in the early part of the 1900s drew the National Geographic. It took them several years to get up a group to go and take the pictures of the Valley of Ten Thousand Smokes. It captured the imagination of American's. Now, that fumarolic activity in the Valley of Ten Thousand Smokes in the Aleutian Islands is quite again. We saw an eruption in 1980 at Mount St. Helens and now it's quite again for another 20 years. What we have to be constantly be aware of is that these volcanoes could go again. These are not extinct volcanoes. They are dormant in terms of many generations of human life span but they can come to life again. We debated, Jack Renton and I, last week. He suggests, as many do, that Mt. Rainier might be the next one to go. I suggested that Mt. Baker is also one that has demonstrated some pretty strong activity. It's not always so much the volcanic material that it's ejected but the lahars. The melting of the ice cap and the snow cap combined with all the rainfall that occurs in these volcanic events. Sweeping down all the loose unconsolidated debris on the slopes, confined in the valleys, and that's where we have built our condominiums. We have condominiums right outside the park in Rainier. It's a beautiful view, but, we are still living in harms way.

Let's move on to Hawaii. In Hawaii, Deb, we've several different types of volcanoes. The extinct ones and the active ones. What in general do we have?

Dr. Deb: Since we have a hot spot and it happens to be on a ocean crust. What we have are basaltic type eruptions. From previous discussions we mention the fact that basalt is a low silica type of lava. Therefore, the gases that are found in lavas don't tend to be trapped. They are easily bubbled out. It's high iron and high magnesium. Very low silica. A netlike web doesn't form between the silicas and so gas as it manages to eek it's way up through this fairly smooth flowing magma can escape fairly readily. These basaltic flows then will just kind of bubble up and smooth out in what we call a type of shield volcano. There are very low lying volcanoes. The sides aren't very steep and you can pretty much out run a lava flow there as long as you're not on an incline.

Dr. Bob: Even then, the eruptive phase, often along rifts and tears, so the material may go up a couple hundred of feet. If you're really goofy you can get killed. But we presume you're not and that you would take due care if you were in the proximity. But, this is often thought of as one of the great active volcanoes because you can go up and look at the caldera. But, we're talking about the big island of Hawaii. That's where they're active. Then there's another little cone, but it's on the sea floor. In the Hawaiian chain the volcanic material dates, this is by potassium argon because the Carbon 14 dating technique only works back about 40,000 years, where potassium 40 goes to argon, the gas in one step, the gas gets trapped in the rock. You make assumptions when you obtain a radiometric date that all of the argon in the rock is there because of breakdown, radioactive decay from radioactive potassium 40. We do other refining. We look at isotopes, potassium 40, potassium 39 ratios, and we massage the absolute dates that we get. Realize that these aren't that precise because each island was occupied over this hot spot and in fact, the hot spot has been here for a long, long time. The oceanic plate then is moving and there is a hot spot underneath and as the oceanic plates moves then there is this potential for the stratovolcanoes to build and some of them come above water. Of course, in the case of the big island of Hawaii, it is a huge mound. It's bigger then Mount Everest. If you count the elevation from the sea floor to the very peak. There's snow up there, you can go skiing. It was glaciated during the Pleistocene. The climate does not support glaciers today but it is a truly spectacular area. You can actually go up and look into craters and caldera's. There are five major craters. What also happens in Hawaii is that there are satellite breakouts that the eruptive phase often comes out closer to the ocean and then the lava flows down into the ocean and great billows of steam when it instantaneously cools. I'd point out one other thing. As lava comes out it cools and crusts over. You can especially see this at night. It's glowing and it's red and orange. Suddenly it's like somebody turns off the lights because the crust cools. The crust is still very mobile and it's being moved along and suddenly the crust breaks and it dives down under and you see this glow of red and orange again as the molten lava reappears. Geologist's, early on, watching those cool plates of lava just slip below. What if that occurred on a bigger scale? What if what we are seeing in a crust of the lava flow that slides down into the lava is the same thing that happens, with say, a huge portion of the Pacific floor. Sliding down beneath the continental mass of South America along the western margin. Indeed that's where the first thought, you know how the scientists, you see those little light bulbs in cartoons, that was the light bulb that started the consideration of subductions zones. Watching these slabs of lava cool quickly and then be subductive again. Of course, along the margins there is a tremendous amount of potential for failure by submarine, below the water level, landslides. It just creates greater and greater masses that are a composite. No longer is it strictly deposition from lava cooling, but it's a mixture of lava and then landslide debris, made up almost entirely of lava but also incorporating some of the other debris along the coast. The islands are in a warmer climate. There are areas where there are reef structures and organically or biochemical precipitate of calcium carbonate that makes that material. The white sand beaches in Waikiki for example, they import it. They bring it in because it doesn't naturally grow right there and the wave action and the pounding action keeps destroying it. The other factor, unfortunately, is of the many problems and the destruction of paradise. One of the great ones is that by building on the islands we create a great deal of runoff of silt. That silt gets swept out by rivers, mantles the reefs and kills them in the near shore area. We have done terrible things overall to the bioherm that exists. The entire web of life on Hawaii throughout the years of building.

The last one we want to talk about here is Sunset Crater. You've been to Sunset Crater too, haven't you?

Dr. Deb: You bet! I was there about the same time you were.

Dr. Bob: That was a couple of years ago. Sunset Crater is just north of Flagstaff, Arizona. There's a whole field of cinder cones. This is in the monument classification. It's part of the San Francisco Peaks volcanic field. There is adjacent to Flagstaff, Arizona, just on the northwest corner, a huge massive peak. Skiing is off the slopes of that peak but the rock is black. Just on the east side of the town of Flagstaff, on Route 40, it's on the other end of the extension of the National Road. The rock that's quarried there is black and quarried and sold for fireplaces, for grills. It is lava. It's vesicular and it can be used for those purposes. If you drive in that area you come to expect that you're so close to the Grand Canyon that you're going to be seeing sedimentary rocks in layers. On Route 40, which is only a few miles away from the San Francisco Peaks, that's exactly what you see. All of a sudden there's a big black horizon and that's the lava flow. The roadcuts right on Route 40, south of the town of Flagstaff, demonstrate that very markedly. That those old sedimentary rocks, mostly Paleozoic, some of them Mesozoic in the region on what is called the Kaibab Plateau have been truded by rather recent volcanic activity. The eruption was less then a thousand years ago. The last eruption is often spoken of about 900 years ago or so that Sunset Crater actually erupted. I saw in the newspaper that they have finally declared it off-limits. They're not going to let tourists climb it any more. They have a satellite one that they may let people climb but these cinder cones on a continent are such that when you take two steps up you go back one and a half steps and you have moved great quantities of cinders beneath your feet. It is a very, very delicate environment so as thousands, upon thousands of people climb up that cinder cone they are eventually going to destroy and cause greater erosion then should be done.

Dr. Deb: The trails that some have taken were actually closed when we were there. I don't know if you realized that but they point out, if you look up on the cinder cone, you can actually see the old trails. It was a big deal, kind of like climbing Mount Washington for these affluent people with nothing better to do to climb to the top of the trail. It's not that high but it takes a great deal of energy to climb up that loose material to get there. You can see what little volunteer vegetation on this crater was being destroyed. For ecological reasons they have closed it. Wupatki has a cinder cone you can climb to the top of.

Dr. Bob: That's a site, there are many sites around that area, where you see the Anasazi or the ancestors of the people that lived in those regions and the ruins of their civilization. A fascinating area.

Dr. Deb: They actually used dendrochronology to figure out when this last erupted. They used the tree rings and found out that by using dendrochronology it was about 1064 that this erupted. The fellow at Arizona matched up the tree ring thicknesses and figured out exactly when those pit houses were buried that happened to be buried in that flow.

Dr. Bob: They did quite a bit of work, the University of Arizona has a tree ring or dendrology laboratory and they have constructed by combining archeology with the geology. They have constructed a cycle of going back a long, long time. The trees that were cut and incorporated in the lodges. The climate through the dendrochronology for exactly the reason, a good healthy climate year. A summer with a good deal of rain, good growing season, and so forth. Then, they match them up along the edges and the contacts. Apparently the Anasazi brought that wood from a long, long way. Any civilization, even those early ones, wiped out the vegetation nearby. I recommend that if you do go to that area, what you would do, of course, is go to the Grand Canyon. Also, go to the Sunset Crater area at Flagstaff. Take some time to go a bit east to Meteor Crater and you really have to go over to Petrified Forest. It's a drive over. To some people it's not spectacular but to Deb and I, it is....aah. Just looking at those gorgeous, beautiful logs, now long since replaced by silica. A multitude of color. This was their forest growing there. These's trees swept down. Think in your minds eye as you say, the burial, the preservation and now they're exhumed again. It is a truly spectacular area overall.

Well, one of the things we wanted to talk about before break is about Yellowstone and Hawaii. How would you bring those two into the classroom and talk about that and compare and contrast?

Dr. Deb: The most obvious thing you can do with any age is to bring in the types of rocks that might be found in Hawaii and Yellowstone. For even the youngsters, are these two rocks the same? If they aren't, how are they different? The youngest children will look at color. That will be their first thing. They might look at grain size. They'll see an automatic difference between the basalts and the rhyolites, perhaps you through in a granite in there they'll definitely see that. As you get a little older you can talk about cooling rates and the fact that you can bring maps in and then talk about where these two places are located. Use that as an exploration. Talk about the different types of rocks that you would find in them. Then, start to inquire as to why these two rocks happen to be different. Why don't volcanoes through out the same types or rocks or form the same rocks? If they don't know anything about hot spots, at this point this is a great way to teach them about hot spots. What you can actually do is, once you get a look at the rocks, get a look at a map. Go to Hawaii first and concentrate there. If you go to an island map have the kids take a look at that and then say where is the active volcano now? What do you think formed that island? When they start to associating the formation of the island perhaps with the volcano, ask them to measure the distances between those islands. They have to use a map scale, their rulers. They have to determine then this distance between the islands and convert it into centimeters. If you give them the estimated ages of the rocks, which you can find in many of the textbooks, pick something in the middle, then they can determine the approximate age for each of these islands and you can make some observations. What do you notice about the age of that particular island and it's distance from Hawaii? Where is it erupting now? They can draw conclusions then about the fact that this might be a moving plate. If not, that's where you start attaching the content to it. Talk about the fact that this is a hot spot, that the plate is moving. If the plate is moving can you figure out how fast that plate is moving. The groups start talking about then, can we take this age and come up with a velocity for this plate? It might not be right but at least they've gone through the process and they'll probably come pretty close given these ages listed in the textbook and using the scale. The kids start incorporating math. They start using scale. They're using many, many skills in order to arrive at this answer. Instead of you telling them a) write down the age of this island b) write down the distance of Hawaii from Oahu, then divide this by this. Let them wrestle with this for awhile. See if they can come up with the answer, the technique used to determine that distance.

Dr. Bob: This was the average. It's simple, just an average, it helps bring in mathematics into the laboratory. Demonstrate that math and science are linked and always have been. Math is not a difficult thing but a very useful thing in working with these features.

Dr. Deb: You can ask them what direction they think the plate is moving. They have to struggle a little bit, here's the island and here's the hot spot, can I figure out which way this plate is moving. Do they think the plate continues to move in this direction? You'll probably say, I suspect there's probably islands out here. Then you bring the Emperor Sea mountain chain and you show them that map. You see then that the angle at Midway Island then shoots north they can begin to understand that that plate didn't necessarily move in that direction forever. It has actually changed direction. There are many things you can do with the Hawaiian Islands in terms of drawing in math. Discovering actually what a hot spot is. How to apply that knowledge, this is a little bit more difficult but now that they have done this for Hawaii can they do this for Yellowstone? There are a couple of calderas there. We have some ages, ranges of ages of dates. About 600 million years to potentially figure that out. They could do a distance.

Dr. Bob: Tell you what, Deb. One neat thing. They could off the globe determine what this total distance is out to Midway. Ok. The distance from Hawaii to Midway and then make assumptions. Can they predict how old the rock might be at Midway. A prediction. You'll love these predictions. Make them decide what you have to have to make an assumption. The actual date is about 45 million years for the rock at Midway. Then what's even more interesting is that this Emperor Sea Mount goes almost up to the Aleutian Islands. Why? Because it is subducting, going underneath, we're losing them. The Aleutian Island arc and then can they predict an age just before it goes under the Aleutians. As you look at the globe, look to see if this distance is about the same as this distance because the age appears at about 85 million years. Think of the excitement of the kids doing it themselves. Predicting themselves. Maybe you can supply them with some information, precise data to help them with that.

Sorry I broke in with that but I wanted to bring that in because now you're going to talk about Yellowstone. We'll have these on the web site. We'll have pictures on the web site. What Deb has done is put together four examples. We're talking about Yellowstone and Hawaii. We've also pulled two others from the Cascades. The crust type on which it exists then what?

Dr. Deb: We have the plate dynamics. What's actually causing this volcano to be here. We can't really call it plate boundaries because hot spots aren't plate boundaries. I refer to it as dynamics. We know that Yellowstone and Hawaii are hot spots but the Cascades then are a convergent zone or a subduction of oceanic crust beneath continental crust.

Dr. Bob: Then, the lava is more viscous, a yellowish type rock.

Dr. Deb: More silica. If you think back to the plate that's associated with it, it's a continental type crust. Whereas, down towards Hawaii then we have the basaltic.

Dr. Bob: This would simply imply that it just blew it's top. Caldera, crater.

Dr. Deb: We have this distinction that we need to make in that a crater is distinctive. It's different then a caldera. A caldera is sort of implodes, collapses. What was beneath it has been removed and so it just caves in on itself. It usually is considerably larger although not always. In this case Crater Lake is not really a crater, it's a caldera. Yellowstone is a caldera as well. What we have in Hawaii and Mount Rainier are considered craters. You can compare when these eruptions have been going on. Whether or not that's the last for Yellowstone, we don't think so. The thing is we may have misspoken a few moments ago and called that 600 million but it was 600,000 because there was one about 2 million years ago. There was one about 1.3 million years ago and then this one about 600,000, rounding it off. Is there any pattern to this? Is there a suggestion that we are closer to another eruption or are we far away from another eruption? The interesting pattern is that there seems to be some hint at periodicity, although really all we can say, this is episodic. There are multiple episodes. Periodicity implies we can actually predict the next eruption and that's not really true. What else did you prepare here Deb?

Dr. Deb: There seems to be a little bit of confusion about terms that we toss around from time to time. We keep talking about pyroclastic debris and all we mean by pyroclastic, pyro meaning fire and clast meaning broken in Greek, is anything ejected from a volcano or a volcanic explosion is called pyroclastic debris. We also call it tefra. If you hear that term tefra that's all we're referring to. What constitutes tefra? If it's a chunk and it's thrown out of a volcano then it has a size associated with it. If it's greater then 32 millimeters in diameter it's either referred to as a block or a bomb. That's something that ejected when it's hot and molten or clastic. It actually forms aerodynamically as it flies through the air and it cools. It actually cools before it hits the ground. You get these spindle type structures. If however it is ejected cold, or it's already solidified and its kind of a blocky chunk, it's not a bomb, it's called a block. Then you have cinders which we call cinder cones. Although any size particle can be on a cinder cone but generally it going to be anywhere from 4 and 32 millimeters. We have ash that considerably finer or between a 0.25 millimeter and 4 millimeters. Then, what we refer to as things that kind of circumvent the globe once an enormous eruption like Pinatubo might take place is the dust or the particulate matter that can be carried by the wind. Those are the pyroclastic categories you might have.

Dr. Bob: Then, we also use the term lava. Recall again in conclusion for this part if the program that we have too types of lava, low silica is by far the more abundant. The rock type is basalt, black sometimes brown. It's the rock of the ocean floor but it's also the rock in Hawaii. It also can be found in places along the Cascades. The high silica can yield the type of flow of lava, rhyolite. Rhyolite is a flesh colored rock that when weathered there's just enough iron present overall and will stain it a bit yellow. It's the yellow rock or yellow stone that's so well exhibited in the walls of the Yellowstone River Gorge. You can see layer after layer there of the rhyolite. If you were to take a rafting trip down the Colorado or the Snake River you'd see layer after layer of the dark black rock in the canyons there, those were basalt flows. Lava flows can go great distances. They just happen to be more confined in the extend of the caldera in Yellowstone but the lava flows that formed the Columbia River basalts cover vast areas of Oregon, Washington, and parts of Idaho. They went a long, long distances. A hundred miles or more.

That brings us to our break time. Let us have a brief break here. We'll cover the additional national parks right after the break.

BREAK

Dr. Bob: (Joined in progress) by water or by ice that is created some of the great spectacular scenery. In Utah there are three national parks and I would urge you to see all three. The three national parks are Zion, Bryce Canyon, and even though there is only 50 miles apart Bryce Canyon is over a thousand feet higher in elevation. So there's a different ecosystem and it's really spectacular and then Cedar Breaks is a small little feature. My personal preference is to see Cedar Breaks after a snowfall because the green of the cedar, the multicolored rocks that are exposed and the snow are just absolutely mind boggling.

Dr. Deb: There's another one, actually, Snow Creek Canyon. There's a cinder cone there.

Dr. Bob: One of the features to show. This is a highly structured area. We are getting into that part of the country known as the Basin and Range. The Basins are often the D, downthrown of normal faulting. Normal faulting simply means it looks like a gravity fault where there may be an angle to the fault surface but the downthrown block creates basins. Many times in the Basin and Range Province the basins are undrained. They are totally enclosed. Some areas like around Salt Lake City one finds the large lakes that are still present as in the Great Salt Lake where it doesn't drain anywhere. It's all internal drainage. During the Pleistocene when it was cooler and wetter in this area there were many, many basins that held lakes. Lake Bonneville, the salt flats where they test cars and set speed records is another example. There was a major fault, the Hurricane Fault. Another fault the Severe Fault and sometimes it's stepwise faulting and other times it creates specific basins. The plateaus stand up high and the valleys are often along the fault lines. That's the way it is in Bryce Canyon. You ride up onto the plateau and you look down into the national park that is Bryce Canyon. In Zion you're down in the valley. The Virgin River and Forks of the Virgin River have cut very deeply into Zion National Park and there you're down in the valley and you look up at the spectacular walls.

Dr. Deb: This is called the Grand Staircase, is that right?

Dr. Bob: The Grand Staircase is often is multiple. You see some of these in Arizona too. As you come north out of Phoenix you keep going stepping up and up. The different plateaus are established by faulting and then accentuated by erosion. You're constantly have the appearance of climbing again, again, and again. If you go to the Grand Canyon, the Grand Canyon isn't too far down to the south about another hundred miles to the south. At the Grand Canyon's North Rim you're at a much higher elevation then at the South Rim. You're constantly seeing these different plateau levels. They are spectacular upland flat areas. Sometimes these rivers are simply accentuating faults or joints in the rock. They have followed it. At the Virgin River, it's very much in line with the faults not because it necessarily, in this diagram, shows a fault but rather the rocks are jointed in parallel sets and then perpendicular or near perpendicular sets to the fault plains. This region then, overall, shows and demonstrates rocks of different geologic age. We're doing a combination here of Bryce and Zion National Park because as the geologists would look at it, we would talk about the oldest rocks first. Let's talk about Zion National Park. I have a black and white photo that demonstrates where the Virgin River is cutting down, it has cut down so rapidly because the rocks are not that well cemented. They are all sedimentary rocks, they're all Mesozoic age rocks. But in Zion National Park, these rocks are Jurassic in age. The three ages of the Mesozoic from oldest to youngest, Triassic, Jurassic, and Cretaceous. The Jurassic rocks at Zion National Park, in the black and white pictures you can see the intense cross bedding, the throne, the great white throne. The lines seen to cross and are eroded. That's called cross bedding because the cross bedding was created, these are really frozen sand dunes. They are of Jurassic age. When you go to the national parks look for the geologic columns. Look to understand where you are in geologic time. Always on the left we have the eras. Here is the Mesozoic Era. Then, the Triassic, the Jurassic, and the Cretaceous. When we get to Bryce National Park you're up into different rocks of the Cretaceous Age. At Zion there is the Navajo Sandstone. The Navajo Sandstone, white cliffs, they're old migrating sand dunes. At that time the great continental mass, very much interior, sand dunes suggest that there is a lack of vegetation to hold the grains in a good prevailing wind condition. It does not always mean that sand dunes imply an arid environment or semiarid environment. We could take you around the United States and show you sand dunes in nearly every state. For example, where are the sand dunes in West Virginia? They're pretty well obscured by trees and a couple of picnic tables but if you go along the Ohio River in Jackson County at the aluminum plant there are sand dunes in the little employees park right near the main entrance. There are remnants of sand dunes. There were other sand dunes in West Virginia but they pretty well taken them out and sold the sand. Along the northern panhandle there were sand dunes when Europeans first came in. They weren't active sand dunes, they were anchored by trees and vegetation. They got excavated with the rest of the sand because it was needed as aggregate, as the development of the Ohio River Valley took place. Bryce Canyon, ancient sand dunes, spectacular scenery. To demonstrate, the river cuts down and then the debris falls down. There was a landslide that did shut down the park for several months because it was a massive sheet of sandstone that had fallen off and shattered on the floor, on the road, and took a long time. They were afraid they had lost nearly the entire season that particular summer but fortunately they got it cleared and got people back in. Just a few years back too.

Dr. Deb: This is sort of the case that we see up at Coopers Rock, isn't it? There's an underlying shale that's a little bit less resistant to weathering and when that erodes away the Kienta formation, I believe is a shale, and as that erodes it allows the sandstone blocks to come down a lot quicker then they ordinarily would.

Dr. Bob: It's not in the case of Chestnut Ridge and also in the case in Beartown that there you see the sandstones but you don't see the finer fluvial sediments beneath it, the silts and that. But they are there and they are instrumental in creating the slopes below. It's not quite as pronounced when you're in the valley here but what is pronounced are these big massive cross bedded sandstones.

Dr. Deb: How would a teacher ask this, because they're students would obviously make this conclusion also. We see cross beds all over West Virginia and we say that they're river deposits. How do we know when we look at Zion that that is actually a dune deposit and not a river deposit like what we have in West Virginia?

Dr. Bob: I was just going to mention that. When you stand on the rock at Coopers Rock you look back, it's very, very obvious that there are packages and it appears that those packages are layer upon layer. Now what those really look like are little deltas. In a delta we often speak of three types of deposits. The topset thin and just covering it. The foreset as the individual grains are dropped off are dipping and then way out in the deeper water the bottomset. These foresets implies that the grains in each of those packages were marching along and falling down a face. All of this taking place in minutes, hours, days. That we say looks like a river, however when you get to the Great White Throne in the Navajo Sandstone you see this chaotic bedding and the packages can only be outlined as being stacked together, not one on top of each other. This then is finally demonstrated a desert, a dune, by doing two major things. Number 1, look at the grains. Put under a simple binocular microscope and you'll find that these grains are frosted. It's grain against grain in the wind and it makes little pock marks. In addition to the frosting of the grains we try to get other mechanisms. Number 2, we go excavate a live dune. We dig in one and when we excavate we find this same type of crossbedded features. What we're using is the idea that the present is the key to the past. We are looking at what the grains and sediments are telling us. When you look at the grains at Chestnut Ridge you'll find that the grains are polished. They look very clean and smooth. They've been rolled along in the river and therefore they've been adjacent to smaller particles and polished and shined. Much like what you might do in a tumbling machine. Perhaps you've done this in your class, put some nice looking rocks in with a finer sand and tumble it for awhile, then take the rocks out and wash the rocks, put it with a finer sand, called grit. The different grit sizes, the analogy of course is sandpaper. Take the coarser sandpaper and rub a piece of wood and you leave streaks. The wood doesn't look as nice. You take the finer and finer sandpaper and you work on that and you buff it down so it's really smooth. The scratches are microscopic scratches and therefore are basically lost in the process.

Now in the context in the direction of these, remember that this was a clear direction, in the context of the direction of the sand, sometimes you're going to find that there seems to even be backwards. Remember the wind can blow from many quadrants but in general there will be a prevailing wind direction. Today for example, if we were to talk about a prevailing wind direction over the heartland of the United States we would say that they are west to east, in general, but that includes the fact that the wind maybe under the control of the jet stream and it may be anything from the northwest to southeast. The southwest to the northeast or almost west to east. You have a series of quadrants there that you have to work with to get an idea of what the wind direction was. You can work on wind direction in the sand dunes but it is more difficult. You don't see it immediately, you have to look at more rocks. That's Bryce, Zion, and Cedar Breaks. If you fly into Las Vegas you can obviously go over to Hoover Dam or Boulder Dam, one of the great tours. The thing is you may have to wait to get across. The number of people using that is unbelievable. The delays getting across there. Also of course to just witness what is going on in that area where people ought not to live because the natural resource is not there and we bring it in and that's water. We take that water from the ground, but more importantly we take it from the Colorado River. There are so many learning activities while you are in Las Vegas.

Dr. Deb: Valley of Fire is another one, just north of Las Vegas on the way to Zion if you're traveling up that way.

Dr. Bob: We will revisit general area in Nevada because it is not that far away from Las Vegas where they are working at Yucca Mountain for the repository for high nuclear waste. That's later in the semester though.

Ok, Carlsbad Caverns. Carlsbad Caverns, what goes on? Chemically, traditionally, do we have caves in West Virginia? Yes. Many states have caves. What are the rocks we usually find in caves? Limestone, dominated by the mineral calcium carbonate. How about dolostone? Sometimes called dolomite, calcium magnesium carbonate. The possibility exists that marble, the metamorphic rock. If it is not a marble where silica has replaced the carbonate then the marble still could be calcium carbonate and we often call it a soft marble. Soft marble is the type of marble that we're using for tombstones and facing stones. We're usually thinking of that and in the solution weathering, we're usually thinking of the possibility of water in the atmosphere plus a little bit of carbon dioxide. These carbon dioxide molecules are not that soluble in water. In order to get the pop or the soft drink that you had we actually force carbon dioxide into the water. That's why if you shake it and open it, it all comes back out because it's not as perfectly solulable as you would like it. It's a simple chemical statement, H₂CO₃, carbonic acid. When it's pressed into water it's called carbonation. That's where we'll see the weathering phenomena. But not Carlsbad. Because of the nature of the chemistry of the cave and the testing the rest of the atmosphere. What we think, it's still a limestone that's been dissolved, but, the rocks underneath supplied hydrogen sulfide gas. That combined with oxygen in an oxidizing environment creates the potential for H₂SO₄. That's the acid that's worked on the beautiful caves at Carlsbad, New Mexico. The rock itself, it's a long way to get to Carlsbad. It's almost 300 miles from Albuquerque, a whole days drive, you can't go straight down. You go south and you come back to the east or you fly into the panhandle in the Permian Basin in Texas. The Permian Basin is a geologic term and very appropriate because the rocks at Carlsbad, the limestones are Permian in age. It is the site of a massive reef. Carlsbad Caverns then is dissolved out of rocks that's chock full with fossils and fossil fragments. It is perhaps of the commercial caves often named as the most spectacular commercial caves for all the dripstone that's present. In the east we often think about Mammoth Cave in Kentucky or perhaps Luray Caverns in Virginia. Those limestones are of different age and Luray is Lower Paleozoic. In Mammoth Cave it's Mississippian. The same limestone we have here in West Virginia. The Greenbrier limestone, not called Greenbrier in Mammoth Cave but the caves in the east have been ravaged for 50 years or more by thrill seekers. In the case of Mammoth Caves which is much more interesting is that Native Americans had gone into the cave many, many years before Europeans came. A long time before and there's evidence of moccasins and we've even have found archeological finds of reeds that were bundled together and burned at the top. They were left behind. They went in with torches. What were they going after? Probably after some of the spectacular blue minerals that are part of the cave onyx. They could also have been collecting bat guano, the saltpeter material. In the Civil War they went after the bat guano in order to get material for munitions.

Dr. Deb: They did a good bit of this mining in Carlsbad for the bat guano. They lowered the cave floor almost 50 feet trying to extract that. A hundred million pounds to be exact. The only thing that saved Carlsbad was that the entrance had a sharp drop off and not even the Native Americans used it. We got lucky.

Dr. Bob: The point is that Carlsbad has spectacular dripstone and cave onyx, stalactites, stalagmites still. It's a well traveled, well guided trail. There's another one in New Mexico along the Texas border, Letchigea (sp.) that is in the United States, the most spectacular cave. There is not commercial activity there.

We wanted to include a national park where solution weathering. Here in West Virginia we have a richness of cave activities. Some of them are very dangerous. Some of them are off limits because of bats, endangered species. There are also caves in West Virginia where the vertical free fall is hell hole for example. Some of them are very, very dangerous and only the most experienced spelunkers should go in. In other places we have great places to take school kids. We stay in the area where we can access very safely. In most cases, Greenbrier and Monroe County, and wherever the Greenbrier limestone in Mississippian age is exposed that's a great caving limestone. We have a cave right outside of Morgantown in the Cheat River Gorge, there are a couple little caves. They're high on the hillside, Cornwell Cave is one example. In the eastern panhandle there had been off and on some commercial activities in the lower Paleozoic, the Cambrian and Ordovician carbonate sequence there where there are also some caves. You had a chance to go to Wind Cave.

Dr. Deb: Yes I did. Cave of the Winds in Colorado. That was of Ordovician age.

Dr. Bob: We have quite a few caves in the Ordovician age too, Germany Valley, but right outside very close by there's another commercial cave in West Virginia and that's in the Silurian, the Sonaloway Caves (sp.).

Dr. Deb: We have one just across the border in the Mississippian, Loyalhanna. A kind of a sandy lime. There's no floatstone.

Dr. Bob: Up along Chestnut Ridge, Laurel Caverns. It's not like down in Greenbrier and Monroe County where there are hundreds of feet of carbonates. Greenbrier and Monroe County were the center of that deposition during the Mississippian in a marine environment. Then it thins and it is also eroded. There's an erosional unconformity over some of our Greenbrier. The Greenbrier thins to the north and then the clastic sediments start taking in and it becomes more of a sandy limestone. In reality, even the Greenbrier limestone in Greenbrier and Monroe is a dirty limestone. It has a lot of interlayered shales or at least if you take what looks like the purest limestone you can find, if you dissolve it with weak acid, hydrochloric of acidic acid you'll find 15, 20, 25% insoluble residue, clay minerals. It was a muddy water. The silicate minerals were being flushed in at the same time that the biochemical precipitate of calcium carbonate was occurring. It's really kind of spectacular there.

Glacier National Park is so named because the carving by ice. This is multiple ice events in the Pleistocene. The Pleistocene is the past two million years. But, the rocks are Late Precambrian in age. This is known as the Belt Series. They are rocks that look old, look cooked but they're really sedimentary rocks from the Late Precambrian. That's what's kind of spectacular because only in this area of Montana do we find sedimentary rocks of Precambrian age. True, it's Late Precambrian age, it kind of straddles the border between the Cambrian and the Early Cambrian, the Paleozoic. But here's the outline of the stratigraphic section and it's called the Belts Super Group because there's so many units in it. The names aren't important but it's the Belts Super Group and then the Paleozoic would have been here but there's a major erosional interval. That's a tremendous erosional interval because in the Cretaceous that's the next rock on top of the Pre Cambrian. It's one of those massive, the Cretaceous are about 80 million years old. These are 600 million years old. There's a tremendous break. There is no space obviously. The rocks are right on top of each other but it is a great unconformity. This type of unconformity then is accentuated because the next deposits are only about 2 million years old. The glacial deposits, or less. Some of those glacial deposits are only a few 10s of thousands of years old. That whole sequence and there's one additional feature, all the features of erosion and deposition, U-shaped valleys where the glaciers have accentuated the depth and the sides. Some of these then, these U-shaped valleys, are enclosed. They are blocked by moraines. Lake McDonald is one of these very, very deep, long and narrow. These long narrow U-shaped troughs are part of these spectacular nature of Glacier National Park. Two other things, one is a massive thrust fault. The massive thrust has taken the Precambrian rocks and moved on weak shale of Cretaceous age. This is known as Chief Mountain. The rocks were thrust at a very low angle many, many miles to the east. Here the rocks are in reverse order. The material that's 600 million years old is sitting on top of rocks that's 70 or 80 million years old. A tremendous fault that's called a thrust fault. All the types of spectacular features we'll talk about this and enhance this in the discussion in the adjunct next week. There's one thing, we're going to postpone Cape Hatteras. We want to comment about the books for the reading, Deb?

Dr. Deb: We're going to post that book list for you this week on the web. If there's any questions just give us a call and we'll clarify. Don't worry about having to pick a different book then everyone else. You're more then welcome to read the same book.

Dr. Bob: Buy one book and share it or even after everyone's read it just circle around and talk about it. I've often found that helpful.

Dr. Deb: Many of the libraries will have John McFee's books so if you don't want to purchase one of these books it easy to find them in the library. Look for that book list posted on the web site. Several of you want to get a jump on this and asking about the paper. What we're looking for in this paper are essentially three parts. One, we need an abstract. Tell us what you read, a brief synopsis don't go on and on and on for seven or eight pages. Two, the second part should be your reaction, a critique. Respond to the material that was in the book. The third part should be classroom applications. How could you use that material in your classroom. I'm not looking for a lesson plan here. Just a description of how this material could be used. How could you get this information across to your students. Again, we're not looking for 13, 14, 15 pages. We don't want to read that much. Say it well, get to the point. No particular length, just what it takes to say this. I was expecting somewhere around 6 pages.

Dr. Bob: We have the last thing, just as we leave, we will talk about this next week. We have a web site where there will be an electronic field trip and the next one will be February 23^rd, February 24^th. A school out of Montana runs this. It will also include, not only Glacier National Park but also some of Yellowstone National Park.

Dr. Deb: The transcripts for the old electronic field trips are there.

Dr. Bob: We will reintroduce that web site on the adjunct. Quiz #1 will be on the web site, posted this week. We've reached the end of this particular session. We depart now from the national parks and next week we will have an adjunct and in two weeks we'll gather together and talk about tools of the trade. What geologists are doing in West Virginia with equipment, materials, maps, compasses and that sort of thing. What you can do in the classroom or just outside the classroom, even on your school grounds. We'll try to have a very practical application of the types of information and materials and equipment available. Until then, for Deb and myself. We've enjoyed tonights session. Take care see you soon!

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

Page last revised: February 2000

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