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Calderas of Juab County

Volcanic Calderas of Millard and Juab Counties, Utah

Usually, when one thinks of rocks and geology it’s all a bit impersonal; after all, they were formed in the distant past, in many cases hundreds of millions of years ago. Most of the rocks in western Utah, where I’m from, were laid down as ocean deposits during the Paleozoic Era. Now all the layers of shale, limestone, and dolomite have been thrusted, twisted, and even overturned, so that in some areas the Paleozoic rocks lie on top of younger Mesozoic rocks. How could this have happened? But in addition to these sedimentary rocks, there are some anomalies; whole mountains that puzzled me because they didn’t fit in. My grandfather, who lived next door to us in our small hometown of Deseret, would take me for drives out on the west desert looking for trilobites or pine nuts or just collecting rocks. One area we visited was Topaz Mountain at the southern end of the Thomas Range in Juab County, where one can find topazes just by walking along an arroyo on a sunny day, following the flashes of light. The rocks there are weird, with strange cavities and a light gray texture much different than the surrounding mountains. I wondered where it came from, how the topazes got there, how old the rocks were, and above all, how geologists were able to answer these questions.

Desert Mt. Pass

View from Desert Mt. Pass

This was all very interesting to me as a child, but then geology got personal. My father was a farmer and cattle rancher, and one day in June of 1971, we were hauling a load of yearling heifers out to our ranch in southern Tooele County (about 50 miles due north of Deseret). As we were driving our old 1952 model half-ton truck over the pass on Desert Mt., the brakes and clutch both failed at the same time and we found ourselves rolling down the steep and winding road without any means of stopping (the road has since been improved, as you can see at right. Back then the road cut along the left side of the pass and was much more dangerous). Dad tried to slow the truck down by ramming it into the embankment on his side, but the impact jarred the cab, flung open the door on my side, and threw me from the cab (this truck had no seat belts). Fortunately, there is a gap in my memory at that point for several seconds. The next thing I can remember is lying on my back looking at the truck as it rolled away from me and disappeared out of sight over the edge of the embankment. Then I saw my right leg, which was twisted unnaturally, with my thigh badly torn up – a whole piece of my thigh seemed to be missing, as far as I could see through the tattered remains of my pants. The best I can figure is that the rear dual tires of the truck rolled over my leg, breaking it in two places and tearing up the skin and underlying tissue badly. Or my leg dragged over the rough, sharp rhyolite rocks of the mountain. Or both.

Desert Mt. Rhyolite

Rhyolite formations at Desert Mt. Pass

This was a hot day in June. We had water and snacks, but my father had sprained his ankle and could not walk. This was before cell phones or even CB radios, and we had no way of getting help. You have to visit the west desert of Utah to appreciate just how isolated it is. Dad lit the truck on fire, hoping the column of smoke would attract attention from the ranchers (including my grandfather) across Ereksen Valley, but no one saw it. Hours dragged by. I was slowly bleeding to death as blood seeped out of my wound, and I was going into shock. After about five desperate hours, my father saw a car sitting on the road leading up to the pass; they had stopped when they came around the corner and saw the smoldering remains of our cattle truck. Dad stood up and waved, and they drove on up. The car was driven by a an elderly couple from Odgen, Utah: rockhounds who were out on the west desert looking for Topaz Mt. All they had was a hand-drawn, inaccurate map and they were off course by 40 miles. Dad was able to ride in to the nearest phone (about 15 miles) and call the ambulance and Doc Lyman from Delta. After several days in Intensive Care, two months in the hospital with skin grafts, and another three months in body casts, I was finally able to walk again. I am lucky to have two legs.

So my life was profoundly affected by the geology of Utah’s west desert. Desert Mt. almost killed me; Topaz Mt. saved my life. So I have understandably been curious about the geology of these two mountains. I can honestly say that I am a part of that geology – somewhere on Desert Mt. there’s a small patch of dirt that used to be me. And that geology is a part of me, too – the doctors were never able to get all of the small rock fragments out of my leg that had been ground in. Yes, I know it’s a bit grotesque, but it’s literally true.

That’s why I’ve wanted to complete these episodes on the beryllium deposits of western Utah before doing any others, because telling that story includes the story of the geology of the area and how those two unusual mountains came to be there in the first place. The episodes are coming along nicely, and I have completed the geology section completely and offer it now for your enjoyment. The first episode (on the sources, uses, and geology of beryllium) will be ready in a few days; the second episode on the mining, refining, and hazards of beryllium will be ready by next week.

Here is the script of this section, in case you’d like to read along with the video:

Geologic Origins of the Bertrandite Deposits in Western Utah

To understand the origins of the beryllium deposits in the Spor Mts. we have to go back to when western Utah was still under the ocean. For hundreds of millions of years, this ocean floor built up gradual layers of shale, limestone, and dolomite. The North American tectonic plate began to separate from the rest of Pangaea about 200 million years ago and was moving westward into the Farallon Plate, which was subducting under the western margin of North America. The sediments carried down with it were heated and rose toward the surface to cool as the granitic plutons of the Sierra Nevada Mts. For the first time, the western half of Utah and Nevada rose above the ocean.

Overhead View of Topaz Mt. Area

Aerial View of Topaz Mountain Area

Then, about 150 million years ago, the North American Plate sped up; instead of moving about 2.5 cm per year, it leaped ahead at the breakneck speed of about 8 cm per year. Instead of subducting, the remnants of the Farallon Plate were pushed under western North America, scraping and dragging the roots of the continent with it. This friction caused a wave of thrust faulting and mountain building to travel west to east across Nevada (the Nevadan Orogeny), then across western Utah (the Sevier Orogeny) about 125-75 million years ago. A huge mountain range rivaling today’s Rockies sat on the Utah-Nevada border, with sediments washing off of it into an inland sea to the east to form the upper layers of the Colorado Plateau as dinosaurs wandered through the mud flats and swamps. These swamps became the coal deposits of central and eastern Utah.

As the thrust faulting continued east, it encountered the thick Colorado Plateau and bent it into the huge anticline of the San Rafael Swell. When it reached Colorado and Wyoming about 55-60 million years ago, the thrust faulting created the Laramide Orogeny that resulted in the Rocky Mountains, including the Uinta Mountains of northeast Utah.

About 50 million years ago the North American Plate slowed down again and the remnants of the Farallon Plate collapsed from underneath, pealing away in a wave that now traveled from east to west. A wave of volcanism traveled with it, moving back across Utah and Nevada. Much of the mineralization found in Colorado, Utah, and Nevada occurred at this time, including the silver, copper, zinc, lead, and beryllium deposits of Utah. In western Utah, the volcanism produced several zones of Andesitic volcanoes with calderas and ash flows, including the Thomas-Drum Mt. caldera along with calderas at Keg Mt. and Desert Mt., about 45-39 million years ago and continued for at least 30 million years through several phases. In the first phase, quartz-rich magmas formed the calderas and ash flows that covered much of the area and produced the gold, copper, and manganese deposits of the Detroit District in the Drum Mts. The second phase of area volcanism occurred as the calderas in the Spor and Drum Mountains subsided and were filled with rhyolite from the Dugway Valley caldera about 38-32 million years ago.

Utah during Oligocene Epoch

Utah During Oligocene Epoch, 30-40 million years ago

The ancient thrust faults and collapsed calderas created fractures, which served as avenues to intrude veins of mineral-bearing magmas. Beginning about 25 million years ago, a third phase of volcanism pushed domes of highly alkaline rhyolite rich in fluorine and beryllium up through these fractures. The fluorine and beryllium minerals formed gases that were injected into the thrust faults and eventually encountered ground water, which flashed into steam, shattering the surrounding rhyolite and forcing the beryllium minerals to precipitate throughout the fractures and empty spaces in the host rhyolite rocks. Gradually, minerals were deposited as crystals of topaz, fluorspar, garnet, and bertrandite in the Thomas-Spor Ranges, and red beryl in the Wah Wah Mts. Additional trace elements such as uranium, lithium, aluminum, zirconium, iron, and thorium were also deposited.

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Panoramic photo of the Book Cliffs, Utah

Panoramic photo of the Book Cliffs, Utah

It’s been a couple of week since I was able to do my last post. I’ve been ill for about 3 1/2 weeks and finally began to recover last week. As mentioned before, I had an unfortunate encounter with a kidney stone at the end of September which had to be removed surgically. I was just getting over that when I came down with the worst case of influenza I’ve had in many years. I don’t think it was swine flu because I didn’t develop respiratory problems, but I had everything else that the flu can give you and had chills and fever for five straight days and was flat on my back for six. Although I wanted to eat, nothing would stay with me, and I’ve dropped about 15 pounds or so since this whole ordeal began. I could certainly stand to lose it, so there’s a silver lining for you.

The Green RIver in Green River, Utah

Anyway, I don’t mean to whine. I’m just glad to be vertical again. I got back on my feet (mostly) in time to travel to Green River, Utah last Wednesday to present at the annual Utah Museums Association conference. My intent was to describe how podcasting can be useful for museums and to drum up some interest in partnerships for The Elements Unearthed project. I was pretty successful in making some initial contacts; one museum, located in Monticello, Utah, is in the middle of the uranium mining boom area of eastern Utah during the 1950s-1960s. In addition to many mines in the area, there was a processing plant and tailings pile in the town that has left a legacy of much higher than normal cancer rates. The museum would help set up interviews with families of victims and others who grew up around the tailings, as well as help tell the history of the boom years. We’d coordinate the videotaping with the local school. Although final details need to be arranged, this is exactly one of the projects I was hoping to do. I also made some contacts with museum staff from Vernal, Utah and we talked about telling the history of the gilsonite and phosphate mines near there, as well as the natural gas and oil shale in the area.

Other contacts were to help with a virtual reality 3D display of the Topaz Internment Camp as part of the proposed new Great Basin Museum to be built in Delta, my hometown. The display would allow visitors to pick a barrack in the camp and the display would then zoom in to a 3D model of that barrack and tell the stories of the people that lived there. The person that I talked to about this was actually my high school English teacher, Jane Beckwith. I still remember how hard she had to work to get me to read anything besides science fiction. Somehow reading some old moldy book by the Bronte sisters didn’t appeal to me much then (or much now, to tell the truth) but I have come to appreciate a few more authors since those days; she certainly helped me learn to write which has paid off in all parts of my life since. I was also approached about doing some work with the Great Basin Heritage Area which includes Millard and White Pine counties in Utah and Nevada. WHite Pine County is especially full of mining history. I’ve already done much work on Millard County for the SURWEB project. The State of Utah Resources Web (SURWEB) was set up to document the history, culture, geography, etc. of Utah by having people take photos and add text that could be turned into slide shows by teachers. It was set up in the late 1990s and the programming for the site is now obsolete; the site is currently down but will hopefully be upgraded soon. For my part, I documented Millard and Juab Counties with photos, text, diagrams, illustrations, and 3D models. I then set up a series of Media Show slide shows for teachers, then created similar illustrations and models for the other 27 counties of Utah. It was, in many ways, the precursor to Elements Unearthed; I’ll even use some of the same illustrations and photos. The best part of it was just getting out on the west desert of Utah with my two oldest children and visiting interesting historical and geological areas, such as Crystal Ball Cave near Gandy.

Ute_panel-s

Ute Indian petroglyph/pictogram panel, Sego Canyon

On the final day of the conference I went on a tour of Sego Canyon, an excellent site for Native American petroglyphs and pictograms. The pictograms were in Barrier Canyon style, dating back at least 2000 years. The petroglyphs were in Fremont and Ute styles. We also visited the old coal mining site of Sego Canyon and took photos of the ruins. Here are some photos of Sego Canyon. The painted rock art (pictograms) are most often of a reddish brown color, although if you look at the Barrier Canyon photo you can see a bluish-green figure on the far right. These colors were made from hematite and probably malachite or azurite combined with some sort of binder (we still aren’t sure what), perhaps egg white or blood. Somehow this ancient paint has lasted longer than the modern paint used by restoration efforts. I hope to do an episode on the chemistry of pictograms and petroglyphs and talk about such things as ancient paints and desert varnish.

Fremont style panel, <1250 A.D.

Fremont petroglyph panel prior to 1250 A.D.

I am now moving into a very active phase of this project as I start writing the NSF grant, which I plan on submitting by Nov. 15. I need to gain some more partnerships and develop an advisory board and a more complete evaluation plan. Even if I do all that needs to be done and write a perfect grant, my chances are about 1 in 10. But I’ve won out with worse odds than that, and the pay off would make this project happen once and for all; I would have the budget to work on this full time rather than doing video work for clients as I am now to pay the mortgage. Wish me luck!

Barrier_Canyon_1-s

Barrier Canyon style pictographs, Sego Canyon

Sego_Canyon_Store-s

Sego Canyon general store

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