Ancient islands

May 27th, 2013

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LOGAN, UTAH–Today we explored the area around Promontory, in northern Utah. Among the many beautiful sites were these rocky, faceted hills that several thousand years ago. This particular hill was intriguing although inaccessible. (It is on a vast tract of land owned by the rocket company ATK. Trespassing is discouraged and no doubt at times very discouraging!) You can see this feature on Google Maps at 41° 37′ 21.11” N and 112° 21′ 42.28” W. Note the cone shape of the top that appears to be sitting on a flat layer beneath. That flatness is a beach terrace of ancient Lake Bonneville. It was formed 14,500 to 16000 years ago by wave action eroding away the hillsides, with the pinnacle exposed above water. (I love wave-cut terraces. Wooster Geologists have noted them before in this blog.)

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Here is a Google Earth view of the scene from the south and above. You can see the terrace cut deeply into the hill and extending to the sides. The highway below is where we stopped for the top photograph. Now note that curvy structure of rocks in the lower right of the above image. A close-up of it is shown below.

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This is a plunging fold. I can’t tell if it is a plunging anticline or syncline because I couldn’t visit it. You can make it out on the lower right of my photograph at the top of the page. These rocks are mantled with sediments from Lake Bonneville. In this case the sediments are coarse sand and gravels because of the lake energy at this shoreline. The exposed rocks are limestones, probably from the Paleozoic.

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On the other side of the valley, on the northwest end of the Wellsville Mountains, two terraces can be seen. The top one against the mountain is the 14500-16000 year-old one we saw throughout the Promontory region. The lower one is younger and made after lake levels dropped precipitously following a catastrophic flood through Red Rock Pass in southern Idaho (which I visited three years ago and recorded in this blog). Note on the lower left that it is being mined for sand and gravel. We see this throughout the area because these terrace deposits are so well sorted and useful in making concrete, building roadbeds, and the like. I learned recently that these kinds of deposits are in a category called “alloformations” because they are laid on top and against much older units.

Oh yes, and what else happened in Promontory, Utah? May 10, 1869!

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The Lodgepole Limestone Formation

May 26th, 2013

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LOGAN, UTAH–Today we hiked up part of Logan Canyon along the south side of the Logan River. Towering above us on either side were massive limestone cliffs, as shown above. The thickest unit is the Lodgepole Limestone Formation (Lower Carboniferous, Tournaisian — about 350 million years old), which is well known throughout the northern Rocky Mountains. I’ve long admired its extent and consistency. It testifies to a shallow carbonate platform that extended from what is now Utah, and Colorado up into central Montana. In fact, correlative carbonates by other names are found from Arizona (the Redwall Limetone) well into Canada. I’ve also been impressed with those many paleontologists over the past century and a half who have managed to pry fossils out of its concrete-like matrix. When they do they have beautiful bryozoans, brachiopods and rugose corals. Some of the best are silicified and removed by dissolving the calcitic matrix from around them.

View of the northern side of Logan Canyon, Utah. The Lodgepole Limestone Formation makes up the major cliff on the right.

View of the northern side of Logan Canyon, Utah. The Lodgepole Limestone Formation makes up the major cliff on the right.

The Lodgepole Limestone Formation is part of the Madison Group of mostly limestones and dolomites. Most of these rocks are affected by karstic weathering, so the terrain often has disappearing streams, sinkholes and caverns.

While the carbonates of the Lower Carboniferous were being deposited in western North America, mixed siliciclastics dominated the east. Last semester’s Sedimentology & Stratigraphy class studied some of those rocks on their field trip to Lodi and the southern edge of Wooster, Ohio. It is always fascinating to look at very different sediments deposited at the same time in different places.

Wooster Geologist on the Wasatch Front in northern Utah

May 25th, 2013

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SALT LAKE CITY, UTAH–It may be a vacation, but even so, every geologist has the delightful duty of enjoying the local geological setting. The above image is looking south from the University of Utah campus in Salt Lake City along the Wasatch Front and the snow-dappled Oquirrh Mountains. We’re standing along the Wasatch Fault, which extends north-south from southern Idaho to central Utah. It is a large normal fault that marks the eastern edge of the Basin & Range Province. It is a beautiful setting for a campus.

Wooster GSA 2012 Poster Take Three

November 6th, 2012

CHARLOTTE, NC – Five Wooster geologists presented their work on day three of the conference.

Whitney Sims (’13) presented her  IS on the emplacement of lava flows in the Ice Springs Volcanic Field (Team Utah). Here is her abstract.

Anna Mudd (’13) presented her work on a Middle Miocene paleosol from the Powder River Volcanic Field (northeast Oregon). Here is her abstract.

Jenn Horton (’13) answered questions about her study of the glacial history of Adams Inlet in Glacier Bay National Park and Preserve (southeast Alaska). Here is her abstract.

Lauren Vargo’s (’13) poster described how she used tree rings to understand North Pacific volcanically forced cooling and drought in midwestern North America. Here is her abstract.

Andy Nash (’14) showed how he used tree rings to investigate drought in northeast Ohio. Here is his abstract.

Tomorrow is the last day of the conference, when we’ll get to see the final two talks and two posters.

The second group of Wooster GSA 2012 posters

November 5th, 2012

CHARLOTTE, NORTH CAROLINA–Matt Peppers (’13), a member of the intrepid Team Utah, presented his poster today at the 2012 Geological Society of America annual meeting. Matt is working on the dynamics of the volcanic flows in the Black Rock Desert. Here is his abstract.

Melissa Torma (’13) showed her poster in the same session. She worked in the Negev of southern Israel on the Middle Jurassic Matmor Formation fauna. Her GSA abstract is here.

The third Wooster presenter was Richa Ekka (’13), who worked on Saaremaa Island in Estonia this summer. Her abstract describing her project with a Silurian shallow water dolomitic sequence is here.

Once again it was a joy to watch our students interact with the many geologists who discussed their posters and projects. I now can’t imagine coming to these meetings without an enthusiastic group of our students.

A day in the Wasatch Mountains

June 21st, 2012

Ephraim, Utah-[Guest blogger Tricia Hall]

After a couple of productive days measuring deformation features and joints, Dr. Judge and I took a day for a fun drive up into the Wasatch Mountains and Plateau. The scenery was much different from that of the desert we were used to. From Ephraim, we headed north climbing onto the Wasatch Plateau. The views were spectacular, and we made sure to stop at every possible place to take in the landscape.

The best vehicle for getting up a mountain...plus it's easy to find.


Along the way we had to share the road with a flock of sheep


Running water! An exciting find for people who walked down a dry creek bed the day before.

We stopped for a short lunch break after making our way down the plateau via the Skyview Drive, and we then made the drive to Mount Nebo on the other side of the valley. Just like on the Wasatch Plateau, we were able to drive through a beautiful national forest as we drove up the slopes. We even ran across features such as Devil’s Kitchen, which seemed very out of place on the forested mountains.

The view from 9000ft in the Wasatch Mountains.

The mini Bryce Canyon...Devil's Kitchen

Once we emerged from the Wasatch Mountains we drove through Nephi to grab something for dinner, and then it was back to Ephraim to prepare for another day in the field.

Final Field Day

June 14th, 2012

FILLMORE, UTAH – [Guest Bloggers Tricia Hall and Will Cary]

We arrived at the field site at 9:30am with the sun already beating down on the lava fields, which are the convenient color of black. Dr. Pollock, Whitney, and Kevin parted with the rest of the group to accumulate more xenolith samples for Kevin’s project. Their group was able to stay close to the cinder cone. This was not the case for the unfortunate followers of Matt Peppers, who had to make long treks across the lava flows.

Team Hot Water (Matt Peppers and followers) started by locating Chubman, the loveable fissure, and set out to track it north. We worked as rapidly as possible in the hope of retiring early from the heat of the day. As we followed the noble Chubman, we found several anastomosing gaping fissures. Some shows some displacement, which was measured by receiving third degree burns from the hot basalt.

Will and Matt measuring the width of the fissure.

Will and Tricia measuring vertical displacement of the fissure, which may indicate a relation with the local fault..

A quick break for lunch under an intense sun left us short of water. We then tried to follow the fissure system to the mapped fault. We ran into an area where basalt debris made it nearly impossible to follow the system farther. We made our way to the fault scarp nearby and measured jointing to help determine the nature of the faulting. After the tracking was done, we quickly measured a monocline along the west margin of the black flow before heading back, our water bottles empty.

Team Hot Water measured these joints along the fault scarp west of the fissure system.

 

 

Team Sandstone (Kevin and followers) travelled around Miter crater attempting to find samples not previously collected.  Kevin began the day with 18 samples and ended with 28 samples, which mean copious amounts of lab work for the young chap. STOP…Hammer time was revamped in an hour-long effort by Kevin Silver to dislodge the xenolith, affectionately named Neopolitan, from the resilient host rock. He did not succeed and resorted to smashing the xenolith with both a hammer and a mallet to analyze the pieces in the lab.

Team Utah wraps up field work for the season.

A Visit to the Utah Core Research Center

June 13th, 2012

SALT LAKE CITY, UTAH – On Tuesday, Team Utah visited the Core Research Center at the Utah Geological Survey. The repository includes cores and cuttings from more than 4000 wells, on-site microscope facilities, and a friendly and knowledgeable staff. We suspect that the sedimentary xenoliths that Kevin has been finding represent Lake Bonneville sediments. Tom Dempster and Peter Nielsen pulled out some cuttings for us to look at and set up the microscope. Mark Gwynn showed us some core that they recently recovered from an area near our study site.

Kevin examines some cuttings under a binocular microscope and projects the image so that we can discuss it as a group.

We also had the chance to meet with Amanda Hintz, a UGS geologist with an expertise in the Black Rock Desert.

Amanda so graciously gave us part of her day to answer our questions about bombs, xenoliths, lava flows, and faulting.

Finally, Stephanie Earls, the UGS Research Librarian, was so helpful in finding historic aerial photographs for us.

Matt, Dr. Judge, and Whitney examine the aerial photos, trying to make sense of the lava flows surrounding our cinder cone.

After a productive day at the research center, we visited Bingham Canyon on the way out of town.

View of the Bingham Canyon mine from the visitor's center.

Although it make for a long day and a late night, our trip to Salt Lake City was instrumental in helping us think about our field area as we wrap up our field season. Thanks to all of the folks at the UGS for their help!

 

The Joys of Mobbing

June 11th, 2012

FILLMORE, UTAH – [Guest Bloggers Matt Peppers, Whitney Sims, and Will Cary]

Wizard Will enjoys some early morning tomfoolery.

With our alarms set for 6:30, we guaranteed that we wouldn’t be up before 7 am. After a hurried lunch packing session, the group headed out to inaugurate Tricia into the research community. She will be doing a project focused on the origin of the basalt islands in the western channel. Hopefully, her project will be used as an analogue for the islands found in the rest of the lava field. We mobbed Tricia in the morning, and through a heroic effort, managed to complete her fieldwork in just under three hours. Dr. Shelley “The Machine” Judge burned through a majority of the 50 individual columnar joint orientation measurements that will help Tricia with her interpretations. While the measurement team ran through the orientation measurements, the rest of the group broke into two smaller teams to collect samples and track out the significant fractures in the area. With each person working toward his or her specialty, the data collection process flew by.

Mob mentality at work.

 

Riding high after a stellar group outing, we moved toward the western breach to take a look at a large fissure Dr. Pollock, Whitney, and Tricia had seen a few days before. When we came across the gaping fissure (nicknamed “Chubman”), we decided to take a well-earned lunch break in the shade of the nearby wall before tackling the measurement process. While Team Fissure worked on mapping and tracking the fissure in the northern end, Team Flow Bandits tracked the fissure south on their way to investigate the possibility of a nearby flow boundary. The familiar call and response of, “Whitney, do you want to take a sample here?” followed by a subdued, “Yes…” echoed throughout the flows as the day came to an end. We had a weary trek back through the sand and sagebrush back to the car, satisfied after a productive workday. Celebratory pie for desert was the icing on the cake to yet another day in paradise.

The "Chubman" Fissure dominates the landscape.

 

A Rocky Start

June 11th, 2012

FILLMORE, UTAH – Today’s return to field work after a fun day in Bryce Canyon was a little rocky at first.

We were a little confused about where to begin.

After a short while, we found our purpose.

Whitney and her team spent the day mapping lava flows that breached the northern rim of the cinder cone.

Fortunately, Whitney had Matt on her team, who chiseled samples from the solid rock with his raw strength.

Will and his team spent another day hunting bombs and blocks on the rim.

In the end, it was a fantastic field day. Will has nearly wrapped up his ballistics sampling and Whitney can practically redraw the lava flow map. Back to the lava fields tomorrow!

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