Wednesday, November 5, 2014

Britt Fiscus
Dugway Geodes 
On October tenth and eleventh I went on a field trip with the Snow College Geology FieldStudies class. One of the stops we made on the tenth was to the Dugway Geode Beds in Juab County. We drove a couple of miles into the beds to find a promising pit, then started searching and digging for geodes. It was a very successful trip and we all took home several geodes. Finding these beautiful crystal-filled rocks made me curious about how they form.
I found out that they form in two different ways. They can form in sedimentary rocks when organic matter such as a tree root, rots away and leaves a cavity in the ground. If the cavity is still preserved in the ground after the sediment becomes rock, it has the potential to become a geode. (Baggaley, 2012) To become a geode, water has to find its way into the cavity of the rock to deposit the minerals that are necessary to create crystals. After millions of years of mineral rich ground water running through tiny cracks in the rock, crystals will form in the cavity.
The other way that geodes can form is in volcanic rock. Cooling lava or magma often contains gases that are trapped in bubbles.  After the lava solidifies into a rock the process is the same as sedimentary geodes.  The geodes formed from water – in this case water that was hydrothermal (heated by the magma in the area) and so it contained a lot of dissolved silica.  This silica rich water seeped into holes left by the gases and precipitated quartz.  This is the most common type of crystal found in geodes. They were formed in volcanic rock called rhyolite. According to http://geology.utah.gov/utahgeo/rockmineral/collecting/rkhd0500.htm they were formed in rhyolite that formed 6 to 8 million years ago.  Then, around 32,000 to 14,000 years ago Lake Bonneville covered western Utah. The lake’s activity eroded the rhyolite that the geodes are found in and redeposited it as lake sediment where we find them today.(Ege, UGS.gov)

References
Baggaley, Kate. "Where Do Geodes Come From?" Scienceline. 20 Nov. 2012. ​​Web. 23 Oct. 2014 http://scienceline.org/2012/11/where-do-geodes-come-from/
Ege, Carl. "Dugway Geodes - Utah Geological Survey." Dugway Geodes - Utah ​​Geological Survey. Web. 23 Oct. 2014. http://geology.utah.gov/utahgeo/rockmineral/collecting/rkhd0500.htm 

Pseudobrookite


An Unexpected Find

Starting October 10th and ending on the 11th the GEO 2500 class went on a two day geology marathon full of traveling on rough dirt roads, hiking, rock hunting and finding. We also learned about some of the major geological events that created the variety of terrain we encountered. We left Ephraim at approximately 8:45 am on the 10th and headed westward to Topaz Mountain. Roughly 116 miles later we arrived at Topaz Mountain. Almost immediately we put on our safety goggles, grabbed hammers and chisels and got to work looking for topaz. We had a variety of success finding topaz, and while looking closely at some grayish white rhyolite I stumbled upon a small black crystal called pseudobrookite. 

Pseudobrookite, which is Greek for false brookite, is a rare oxide mineral which usually forms by pneumatolytic processes or by reactions with xenoliths in titanium-rich andesite, rhyolite, basalt, according to rruff.info/doclib/hom/pseudobrookite.pdf. According to dictionary.com and merriam-webster.com, pneumatolytic means formed or forming by hot vapors or super heated liquids under pressure, the process by which rocks are altered or minerals and ores are formed by the action of vapors given off by magma.  Pseudobrookite is often found with hematite, magnetite, bixbyite, ilmenite, enstatite-ferrosilite, tridymite, quartz, sanidine and topaz. The topaz at Topaz Mountain formed in vugs located in a lava flow, and the pseudobrookite formed in the same rhyolite as the topaz in a similar process.   Pseudobrookite , which has the chemical formula Fe2TiO5, often has either a brownish-black, a reddish brown, or a black color. It is opaque with a metallic luster (webmineral.com).   According to http://www.mineralmarket.com/TopazMtn/topaz7.html
Pseudobrookite crystals are skinny elongate prisms with striations (look like grooves) and belong to the orthorhombic crystal system.  


The pseudobrookite was an unexpected find since we were looking for quartz and topaz. We got home late that night tired but successful in finding multiple crystals, geodes, and trilobites. The next day we left later in the day and headed to eastern Utah. We managed to find heaps of gypsum after a long day of traveling, which was very exciting. The two day road trip was a very enjoyable adventure. 

Information gathered from

Tuesday, October 21, 2014



Wanda Williams
A Gem of a Different Color
           
            On a beautiful October morning our small group eagerly piled into the SUV at Snow College. The time of year couldn’t have been more perfect; the weather was amazing. Our clan consisted of Snow students impassioned in the field of geology, and paleontology. We had our esteemed leader, Geologist and instructor Renee Faatz, to guide us. Sailing over the dirt roads, like a ship with the wind in her sheets, we first headed out to Topaz Mountain. The mountain is not much to look at with its gloomy, grey slopes and patchy scrub. But it seems that the most wonderful things come out of drab, dreary rock – and Topaz Mountain is certainly no exception. Besides bearing its namesake, Topaz Mountain’s rhyolite is also host to quartz, garnet, pseudobrookite, bixbyite, and the elusive red beryl. These are just a few of the treasures tucked away within the unassuming gray walls. The topaz, however, was the main reason for our being there.
            The Thomas Range topaz formed from trapped volcanic gasses. Six to Seven million years ago, volcanic vents emerged along faults in the area. The thick, gaseous lava flow contained numerous bubbles called vugs. Inside the vugs, fluorine-bearing vapor sublimated from the lava. In the last stages of solidification, the trapped vapor cooled and formed beautiful topaz crystals.
The topaz at Topaz Mountain can be found in a small variety of colors. The colors range from a nice rich sherry, to light pink, to clear. The reason for this color palette has something to do with good ol’ wholesome sunshine. When the crystals are exposed to sunlight they tend to fade over time. I thought this was rather curious, so I decided to find out why. I rummaged through my field books, remembering that I own a copy about Topaz Mountain; the author and expert on this location, John Holfert, offers this explanation:

            Unfortunately, the color of the Thomas Range topaz is not stable when crystals are left exposed to direct sunlight for extended periods of time. . . .The sherry color of the unexposed crystals is a direct result of exposure to naturally occurring ground radiation for millions of years, probably from trace amounts of uranium in the rhyolite. Radiation causes electrons to be displaced to a higher energy state giving the crystal a temporary color center. Exposure to direct sunlight excites the electrons causing them to return to their normal state, thereby eliminating the color center, resulting in a color shift from sherry to colorless. (4)

Holfert goes on to express that the rich sherry color can be restored if the crystal is exposed to, “strong radiation for a short period of time” (4). This makes sense because I also found out that this is precisely how most blue topaz are created. According to the Department of Geological Sciences at the University of Texas, “Most natural topaz is colorless or very pale blue; the dark blue color, so commonly seen today is produced by irradiation, usually followed by heating” (Topaz).
            Holfert assures his readers that the color change takes about a week to ten days to take place. He also states, “Artificial light, including florescent and halogen light, does not appear to have any negative effect on the color stability of the topaz” (5). I found this to be a relief because I was trying to keep my topaz in eternal darkness to preserve their coloring. Now I can display them without any worries, as long as they stay out of direct sunlight.
            After a very satisfying expedition to Topaz Mountain we were back in the SUV, being blown by the wind to our next grand adventure. Most of us found some very pretty topaz crystals. We all had a really great time.

Notice how the topaz in the foreground is a light pinkish color, while the topaz in the back is a deeper sherry hue.

In contrast, this topaz from Topaz Mountain is colorless. (Mike)






Works Cited

Holfert, John. A Field Guide to Topaz and Associated Minerals of the Thomas Range, Utah (Topaz Mountain) Volume 1. UT: HM Publishing, Dec. 1996. Print.
Mike. CSMS Geology Post. Colorado Springs Mineralogical Society. 5 June 2013, Web. 18 October 2014.
Topaz. Deptartment of Geological Sciences, University of Tx. 1998, Web. 18 October 2014.

Monday, May 5, 2014

Weathering Rinds by Jonathan Major

While on a field trip working in the Grand Staircase Escalante National Monument (GSENM) , a few members in our group came upon several cobbles of chert and quartzite cobbles with an unusual surface that I can best describe as a rind.   Each cobble of chert and quartzite had a black rind 1- 2 cm thick around it.  The cobbles are part of units such as the Canaan Peak.  The same cobbles are found Dakota Formation near Capitol Reef National Park.  The units were deposited in streams during the Cretaceous period of time.   The cobbles have since been reworked and deposited in the GSENM in alluvial terraces.

These rinds, sometimes referred to as patina apparently form from weathering on the outside of the cobbles that were deposited in braided streams deposits.  Analysis of similar rinds show iron, manganese and other elements like silica leaching out of the rock over time.  Some suggest  that the microflora aid in this process. 


Try as we might, we can't find any papers that are specific to the rinds on these Cretaceous conglomerates.  We would like to know more - the composition of the rinds, why they are so common in the Cretaceous (Sevier Orogenic) conglomerates.    Looks like a great future research project.



References
Baker, J. C., Edmonds, W. J., Ogg, C. M. (2001) Research Gate. Retrieved from http://www.researchgate.net/publication/232149104_Quartzite-Cobble_Weathering_in_Alluvial-Fan_Soils_of_the_Virginia_Blue_Ridge

Rajamani, V., Tripathi, J. K. (1999). Current Science. Retrieved from http://www.currentscience.ac.in/Downloads/article_id_076_09_1255_1258_0.pdf

Viveen, W., et al., Reconstructing the interacting effects of base level, climate, and tectonic uplift in the lower MiƱo River terrace record: A gradient modelling evaluation, Geomorphology (2013), http://dx.doi.org/10.1016/j.geomorph.2012.12.026

Wagner, G. A., (1998). Google Books. Retrieved from http://books.google.com/books?id=ADuZDCa08kwC&pg=PA37&lpg=PA37&dq=iron+rinds+on+chert+in+alluvial+terraces&source=bl&ots=txI_5azP_I&sig=PtZAyR89-EaP4nBfxXuCLq8ehVc&hl=en&sa=X&ei=6iVRU_6PJqbq2gXF0IGQAw&ved=0CEYQ6AEwBQ#v=onepage&q=iron%20rinds%20on%20chert%20in%20alluvial%20terraces&f=false

Sunday, May 4, 2014

Diablo the Ceratopsian and more by Jason Scott Dillingham



Many animals and reptiles that exist today can seem relatable to the creatures in the past.  Imagine the beautiful Serengeti, the dry sun beating on your face.  Suddenly you feel the ground pounding and across the way you notice a muscular grey animal with large plates covering its body charging on all fours through the wilderness, armed with a horn atop its nose.  
Now, notice the sun getting warmer and more humid; the plant life: taller, greener, everywhere.  The ground shakes even more as a “snorting, stampeding, five-ton animal the size of a car, with a giant bony frill on its head, and you've got a fairly accurate picture of a ceratopsian dinosaur such as Triceratops” - a larger friend of the rhinoceros - charges by (Carroll, 1988). 
Ceratopsians (Greek for “horned faces”) date back to the late Jurassic period in Asia.  These species preceded Triceratops (up to the Late Cretaceous) and lacked the frills and horns that Triceratops had. Over time, predators such as the Tyrannosaurus Rex  came along and the Ceratopsians slowly evolved to defend themselves (Strauss, 2014). 
On our Geology field trip to the Grand Staircase, we first had to transport - before we even got to any digging sites - a skull of a Ceratopsidea (a frilled Ceratopsian) named Diablo to a museum where he could be displayed for people to view.  It was exciting to relate how large the animal could have been by the size of its skull, and encouraged me, personally, to get into the field and begin finding new things.

Throughout the trip, we broke up into two/three groups, one with Scott Richardson, the other with Alan Titus.  I was fortunate to participate in the group with Scott that went to a site where a discovery had already been made, but not completed.  “[Scott] discovered what is thought to be a previously unknown species of dinosaur similar to a triceratops, the latest in an extraordinary series of dinosaur finds in the area over the past 15 years (Hollenhorst, 2014).”  The discovery is still unclear, but the excitement endures on.

Sources


Carroll, R.L. 1988. Vertebrate Paleontology and Evolution. W.H. Freeman and Company, New York.  Found on: http://www.ucmp.berkeley.edu/diapsids/ornithischia/ceratopsia.html


Strauss, Bob.  Ceratopsians - The Horned, Frilled Dinosaurs.  http://dinosaurs.about.com/od/typesofdinosaurs/a/ceratopsians.htm . 2014

Photo courtesy of James Montgomery

Thursday, April 24, 2014

Ripples


James Montgomery

             On the last day of our exploration into the Grand Staircase Escalante National Monument we ventured into a Hackberry Canyon, exploring millions of years of rock formations. While walking in and around the small creek that ran through the middle of canyon we noticed ripples in the water. Upon closer inspection we could see the soft sand ripples at the bottom of the stream migrating slowly forward with the current. Ripples begin to form through when the water disrupts the grains of the sand on the bottom of the body of water.  The steeper, down current side of the ripple is always at the angle of repose.
            Deeper in the canyon, we noticed a large boulder with lithified ripples dating back to the Jurassic Period.  These embossed ripples had been preserved over millions of years.
What a great example of uniformitariansim.  We could see modern ripples forming in a stream bed next to ripples formed in the Jurassic almost 200 million years ago.




               

Monday, April 21, 2014

The Kaibab Monocline



            During our Geology Field Studies trip to the Grand Staircase - Escalante National Monument the class camped within a structure called the Kaibab Monocline.   To the right is a cross section of the Kaibab Monocline as it looks near the North Rim of the Grand Canyon.   A monocline is a one-sided fold.  This particular one stretches north-south for about 240 km and dips steeply to the east  - up to 60o-70o.  This monocline was formed by subsurface movement on a fault during the Laramde Orogeny between 50 and 80 million years ago.  (Tindall, 2000).

Differential erosion of the tilted rock layers exposed along the monocline has created a series of east dipping ridges and valleys. Differential erosion occurs because less resistant rock layers like shale will wear away more quickly than more resistant rock layers like sandstone.   Here, the less resistant Tropic Shale and Carmel Formations weathered to form valleys, while the more resistant layers like the Navajo Sandstone and Dakota Sandstone formed ridges.  Stream erosion of the ridges creates the triangular hogbacks seen here.   Locally, this is called the Cockscomb. It was the down-warping on the east side of the monocline that allowed the young layers of the Wahweap and Kaipairowits to be protected from erosion.  Had it not been for the monocline, these layers and all the dinosaur bones they contain might have eroded away long before humans came around to discover them.

References

 Reches, Ze'ev. 1977  "Development of monoclines: Part I. Structure of the Palisades Creek branch of the East

Kaibab monocline, Grand Canyon, Arizona." Development of monoclines: Part I. Structure of the Palisades Creek branch of the East Kaibab monocline, Grand Canyon, Arizona. The Geological Society of America, 25 Web. 16 Apr. 2014.    <http://memoirs.gsapubs.org/content/151/235.abstract>.
Tindall, Sarah E. 2000 "The Cockscomb Segment of the East Kaibab Monocline: Taking the Structural Plunge." Geology of Utah's Parks and Monuments 28 pages 1-15.