STOP, Hammer Time

June 8th, 2012

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

On the morning of the 8th, all seemed well. Much like days before, we all arose and began to pack our lunches for the day. However, as we piled into the car, an ominous light started to blink on the dashboard. Low tire pressure. Concerned, Dr. Judge pulled us into a nearby gas station and checked the tires. Much to our dismay, the left rear tire was 10 psi lower than it should be, a repeat occurrence from a few days earlier. Not wanting to jeopardize our upcoming Mystery Fun Day, Drs. Judge and Pollock made the decision to take the car into a repair shop to have the problem diagnosed. While they were gone, they left us to wreak havoc upon the KOA Kampground. We started by swimming and relaxing by the pool, and ended by swimming and relaxing by the pool. All before lunchtime. We retired to our individual cabins to enjoy the lunches we had packed a few hours earlier in glorious air conditioned komfort.

 

Around 1 pm, the professors returned and it was business as usual. Even though we had lost half of our day to a small hole in the tire (curse you, basalt!) we rushed out to mob Kevin’s project for the afternoon. Arriving on the cinder cone at peak temperature made for a challenging work environment (especially after having spent most of the day in a sun-induced stupor) but we turned the afternoon into a very productive, albeit rushed, day. After reviewing the wall Kevin had used to map his xenoliths, we spread out and tried to collect as many of the 16 different types as we could find. After a few small injuries, stumbles, artistic work with a rock hammer, and some sore hands trying to pry the xenoliths out of the uncooperative host rock, we amassed a small mountain of samples for Kevin. As Whitney struggled to bag and record the samples in the gusting wind, the rest of us made one last sweep of the area for any xenoliths to claim.

Aptly named, the "Avocado" xenolith inspired some dinner choices this evening.

The "Sparkly" xenolith refuses to show its nature in photographs.

 

The "Black and Green" xenolith.

Tricia demonstrates proper hammer usage.

We trooped back down the van, and made the dusty trek back to the kampsite, just in time to shower and recover before we left for dinner at six. After a quick stop to pick up a package containing some hardier field notebooks we went of to dinner followed by a stop for ice cream, where the professors revealed the Fun Trip they had planned for Saturday. We will be driving down to Bryce Canyon on the morrow to spend the day in the park. None of us have been there, so it promises to be a unique experience for us all!

What do volcanic bombs, xenoliths, and giant gypsum crystals have in common?

June 7th, 2012

FILLMORE, UTAH – What do volcanic bombs, xenoliths, and giant gypsum crystals have in common? Not much, except that we saw them all during our long and productive day. We met to pack lunches at 7:30 am and finished with student-faculty meetings at 10 pm, so we’re all ready for a good night’s rest, but we thought we’d give you a quick update on our progress.

We spent the morning as a mob on the rim of the cinder cone, searching for volcanic bombs for Will's ballistics study.

Will found a wide variety of bombs, or material that was explosively ejected from the volcano when it was molten. He made a number of measurements that he'll use in his mathematical models when he returns to Wooster.

In the afternoon, Kevin led a group to look for xenoliths, or foreign rock fragments, in a lava flow. This sedimentary xenolith is affectionately named Neopolitan.

At the end of the day, we visited with Larry Gehre, who so graciously showed us his amazing personal collection of rocks. If you have a sandstone feature in your aquarium, it probably came from Larry.

We were all impressed the size of the gypsum crystals in his scrap pile. Note Will's hat for scale.

Although it was long and challenging, the cool temperatures and partly cloudy skies made for a pleasant day in the field. Back to the lava fields tomorrow to check out some scarps and map flow boundaries. Wish us luck!

As We Walk Through Fields of Lava

June 6th, 2012

FILLMORE, UTAH – Whitney and Matt took charge today, leading us on an investigation of the lava flows that extend westward from the Miter cinder cone.

The view of Miter from its lava fields. A tiny reflective spec at its base on the right side of the photo is our van, for scale.

We picked our way across the sharp, rubbly flow surface and learned the importance of careful observation. Although we weren’t looking for bombs and xenoliths, we found both along our path.

A volcanic bomb that has been rafted or carried away from the cone by the lava flow.

Whitney had a successful day of mapping the margins and morphology of a couple of complicated lava flows.

Whitney stands on the boundary between an older, vegetated lava flow on the right and a younger, black lava flow on the left.

Matt’s productive day included finding a spectacular fault exposure, where he made lots of measurements on the fault and associated joints.

Kevin poses at the most significant fault locality, where some of the surfaces display plumose structures for joints and striae for fault motion.

Overall, it was a strong start to the field project, despite the searing sun and blinding wind storm.

A perfectly nice day in the field (if you don't mind winds that will make your hair stand straight out).

We were rewarded for all of our hard work.

For one, we made a new friend.

We also found petroglyphs that showed these radiating straight lines.

The petroglyphs also showed a hand print.

The best reward was the home-cooked meal that we were treated to by Ms. Huntsman, complete with pie.

We hope every day of our field season is just like this one (minus the wind).

 

Adventures in Fillmore

June 3rd, 2012

FILLMORE, UTAH – [Guest bloggers Matt Peppers and Will Cary]

As Dr. Wilson so kindly stated in his last blog post, the Utah group arrived safely at Salt Lake City International Airport on Saturday, June 2. After stopping briefly at a Target to get various essentials, we finished our two-hour drive at Fillmore (see here for how the drive went), the town we will reside in for the next two weeks. We are staying at a KOA Kampsite in some kozy little kabins. After getting acquainted with the campsite layout, we explored some of the finer cuisine options, finally settling on Larry’s Drive-In Diner across the road. Will tried a marshmallow milkshake that gave him enough sugar to power through the jet lag associated with the time zone change. After a filling meal, the group headed back to the campsite for a quick group meeting to go over the schedule for Sunday, which promised to be an orientation day to the Black Rock Desert and what we could expect. Following the meeting, everyone felt the effects of travel and promptly retired to their respective cabins for the evening.

Dr. Judge lays out the maps for our field site.

The next morning, the group met at 9:30 to pack lunches for the day followed by an overview of equipment and safety precautions that we would need for our fieldwork. With backpacks set up, we gathered as much water as we could carry and set out to our first meeting with the Black Rock Desert. We drove directly west out of Fillmore and, although we couldn’t get onto it, saw Ice Springs, our future field site. We drove around the flow front boundaries and were impressed by how distinct and steep the boundaries actually were. Because today was an orientation day, we set out to find some lava tubes in the Tabernacle Hill lava field. Although we were unsuccessful in locating them, we had some good experience using the GPS units. In addition, we spent a lot of time looking at pressure ridges in the lava field, which adds additional complexity to some students’ projects.

Admitting defeat in finding the lava tubes (and questioning the signage that lead us to that area), we drove on to White Mountain, a hulking mass of gypsum sand a few minutes away. Looking for a place to get out of the 93° heat to eat our lunches, we headed to the one tree we had seen in the entire trip. Stepping out of the car almost had us believing we were in the Bahamas, and the white sand proved a pleasant place to sit. As we moved under the shade of the tree, two small owls flew out from its branches. Waiting cautiously in the leaves above us were three more owls, who seemed upset that we interrupted their lunch with our lunch (3 dead mice taunted them from next to where we were sitting).

The glare of someone who's had his lunch interrupted.

Imagining we are in the Bahamas.

After getting back into the car, we asked Dr. Judge and Dr. Pollock what our next stop would be. Getting only a, “Classified” as a response, all we could do is bounce around in the back of the car down a dusty road. We were pleasantly surprised when the trip ended at a natural hot spring. We eagerly climbed out of the car and jumped in.

Nature's gift.

We continued our first full day by taking a quick stop back at the campsite for a change into dry clothes before heading to meet Dr. Wilson’s, aunt, Ms. Sylvia Huntsman. She graciously welcomed us into her house where we played with her two dogs, Zeke and Bogey and ate delicious apple cobbler. When eyes started to droop from too much time sitting in a comfortable air-conditioned house, we excused ourselves to go eat more food. The fine cuisine of Fillmore proved itself once again at the “Garden of Eat’n.”

The first day ended with a final meeting back at the campsite to set a schedule for Monday (the 7 am departure time was a harsh return to reality) and a beautiful sunset.

Wooster’s Fossil of the Week: A trilobite (Middle Cambrian of Utah)

August 14th, 2011

I’ve avoided having a trilobite as Fossil of the Week because it seems like such a cliché. Everyone knows trilobites, and they are the most common “favorite fossil” (invertebrate, anyway). Plus our best trilobite (seen above) is the most familiar trilobite of all: Elrathia kingii (Meek, 1870). One professional collector — just one guy — said that in 20 years he sold 1.5 million of these.

Still, trilobites are cool. They virtually define the Paleozoic Era, appearing in the Early Cambrian and leaving the stage (with so many others) in the latest Permian. They were arthropods, sharing this very large phylum with insects, spiders, crabs and centipedes. The name “trilobite” means “three lobes” referring to the axial lobe (running down the center along the length of the animal) and the two pleural lobes, one on each side. They  also have three parts the other way: a head, thorax and pygidium (the tail end).

Elrathia kingii is a ptychopariid trilobite found in extraordinary numbers in Middle Cambrian dark shales and limestones. There is a geological story here, two of them, in fact. One reason they are so common is that their populations were commonly buried by sediment stirred up in massive storms (Brett et al., 2009). They are among the only fossils found in organic-rich dark sediments because they lived in the harsh “exaerobic zone” at the very minimum of oxygen needed for animal life (Gaines and Droser, 2003). They apparently were the first large invertebrates to exploit this marginal environment.
Elrathia kingii gives us the opportunity to meet a pioneering American paleontologist: Fielding Bradford Meek (1817-1876). He originally described this species in 1870, calling it Conocoryphe kingii (see above). Paleontologists are quite familiar with the name “Meek” following a fossil species because he described hundreds of them. Meek was a native of Madison, Indiana, a place where Ordovician fossils are abundant and easily collected. He was apparently an unsuccessful businessman so he jumped at a chance in 1848 to work for the U.S. government surveying the geology of Iowa. Meek was good at this job and soon was working with James Hall in New York, the country’s premier paleontologist. Meek was eventually based in Washington, D.C., with the United States geological and geographical surveys. After many accomplishments in government service, he died of tuberculosis in 1876 (White, 1896).

Fielding Bradford Meek

References:

Brett C.E., Allison P.A., DeSantis M.K., Liddell W.D. and Kramer A. 2009. Sequence stratigraphy, cyclic facies, and lagerstätten in the Middle Cambrian Wheeler and Marjum Formations, Great Basin, Utah. Palaeogeography, Palaeoclimatology, Palaeoecology 277: 9-33.

Gaines, R.R. and Droser, M.L. 2003. Paleoecology of the familiar trilobite Elrathia kingii: An early exaerobic zone inhabitant. Geology 31: 941–944.

White, C.A. 1896. Memoir of Fielding Bradford Meek, 1817-1876. Biographical Memoirs, National Academy of Sciences, p. 75-91.

Wooster’s Fossil of the Week: Oyster balls! (Middle Jurassic of Utah)

April 17th, 2011

The technical term is ostreolith, but “oyster ball” is much more descriptive. These fossils are found by the thousands in the Carmel Formation (Middle Jurassic) in southwestern Utah. As far as I know, this is the only place they’ve ever been found. Colin Ozanne (’96) worked on these ostreoliths as part of his Independent Study project, and the results of our work were published in a 1998 issue of Palaios. Colin now, by the way, is an Engineer Trial Attorney for the US Army Corps of Engineers in Buffalo, New York.

Ostreoliths are “circumrotatory accumulations” of the little oyster Liostrea strigilecula. The most common form began with a clam shell fragment as a nucleus. Oyster larvae recruited on the top shell surface and grew in the normal way. A current, though, flipped the shell over, exposing the underside that was in turn encrusted by more oyster larvae. These grew into larger oysters until, again, the shell flipped back over. A new generation of oysters then encrusted the older layer. The shell then overturned again and … you get the idea. Some ostreoliths grew this way to almost a quarter meter in diameter. The cup-shaped left valve of Liostrea was an essential feature for ostreolith development. A typical flat oyster would not build the necessary depth with each layer.

Polished section through the middle of an ostreolith showing the curved nucleus shell and calcite-filled bivalve borings.

Closer view of oysters on the surface of an ostreolith. Note how juvenile oysters are clustered within the left valves of an older generation.

Several sclerobionts (hard substrate dwellers) grew with the oysters on the ostreoliths, including the bivalve Plicatula, disciniscid brachiopods and cyclostome bryozoans. Mytilid bivalves also drilled holes (called Gastrochaenolites) in the oyster skeletons to form cavities for their filter feeding.

Ostreoliths, strange and unique as they are, tell us a lot about the depositional environment of the Carmel Formation. The sediments accumulated in these horizons under fairly high energy with periodic storm disturbances. The mytilid borings trapped ooids during formation of the ostreoliths, showing that this characteristic carbonate sediment was more common in the environment than indicated by the rocks alone.

Carmel Formation exposed at Gunlock Reservoir near St. George, Utah.

Regardless of their scientific value, though, oyster balls certainly start good conversations!

Wooster’s Fossil of the Week: A brittle star trace fossil from the Jurassic of Utah

February 13th, 2011

This week we have a trace fossil that looks almost exactly like the animal that made it. A trace fossil is evidence of organism activity recorded in the rock record. The photograph above shows one of my favorite specimens: Asteriacites lumbricalis von Schlotheim 1820 from the Middle Jurassic (Bathonian) Carmel Formation in southwestern Utah. I collected it while doing fieldwork with Wooster student Steve Smail too long ago for either of us to mention.

This fossil was made when a brittle star (ophiuroid) burrowed into carbonate sediment to either hide from predators or to look for a bit of food. Brittle stars are echinoderms that appeared in the Ordovician and are still very much alive today (see below). This Jurassic trace was formed when a brittle star essentially vibrated its way down into the loose sediment in a manner many of their descendants do today. The result is what appears to be an impression of the body (an external mold) but is actually formed by action of the animal.

Green Brittle Star (Ophiarachna incrassata) courtesy of Neil at en.wikipedia.

The trace fossil Asteriacites is far more common in the rock record than the brittle stars and seastars that made it. These traces thus often indicate the occurrence of organisms in critical intervals where they would otherwise be unknown. For example, Asteriacites lumbricalis is found in Lower Triassic rocks showing that brittle stars were part of the recovery fauna after the Permo-Triassic Mass Extinction (see, for a Wooster example, Wilson & Rigby, 2000).

Stony bryozoans get their day

August 1st, 2010

Trepostome ("stony") bryozoan on a carbonate hardground from the Kanosh Formation (Ordovician, Whiterockian) of west-central Utah.

KIEL, GERMANY–The first day of the International Bryozoology Association meeting is traditionally devoted to workshops where participants can listen to experts on a particular group, technique or idea and then ask questions, work out exercises, or study specimens. I went to the workshop on a group of extinct bryozoans called trepostomes. The Order Trepostomata usually produced thick skeletons of the mineral calcite so they are commonly known as “stony bryozoans”. They lived from the Ordovician into the Triassic, and then disappeared forever. They are a difficult group to work with because their diagnostic features are internal and microscopic (thus requiring thin-sections or acetate peels to identify) and the number of important defining characters is still debated. I went to this workshop because Ohio can be considered the Trepostome Capital of the World with its abundant and diverse varieties found in the Ordovician of the Cincinnati area. Any Wooster geology student who has taken the Invertebrate Paleontology course will remember the buckets of these fossils we’ve collected over the years on field trips.

Wooster played a small role in this workshop, to my delight. One of the interesting and somewhat odd trepostome bryozoan types is found in the Ordovician (Whiterockian) at a place called Fossil Mountain in the western desert of Utah. A generation of Wooster Independent Study students worked here with me studying carbonate hardgrounds and the fossils associated with them. We collected many examples of a strange bryozoan we called “Trepostome Species A” because we could not identify it. Later Andrej Ernst, Paul Taylor and I described it as a new genus: Kanoshopora. It is still odd with its variable walls and colony forms. This meeting may have stirred some interest in pursuing its functional morphology (essentially how it lived) and evolutionary placement. A nice contribution from those days in the late 20th Century when we walked up and down the sunny slopes of Fossil Mountain trying to sort it all out.

Longitudinal thin-section view of Kanoshopora droserae showing its complex zooecial walls.

Fossil Mountain, west-central Utah -- the scene of much Wooster geology Independent Study fieldwork in the 1980s and 1990s, and the home of many of the oldest and strangest trepostome bryozoans.

A view of the Wasatch Mountains from above

July 18th, 2010

Looking west over the Wasatch Mountains into the Salt Lake Valley of Utah. Note the beautiful syncline in the center of the image. Flying across the western United States is such a treat for a geologist. These are the kind of structures the Wooster Utah team is enjoying this summer.

The Bonneville Flood and where it began

July 17th, 2010

DOWNEY, IDAHO–Lake Bonneville has been one of the geological themes of my short visit to northern Utah this summer. The remnant wave-cut platforms of its shorelines dominate the geomorphology of the Logan area, and the lake sediments are the basis for the rich soils of the Cache Valley. Today my parents and I visited Red Rock Pass in southern Idaho where this massive lake breached a weak area of limestones and shales 14,500 years ago and then catastrophically flooded the land to the north. The Bonneville Flood was not as large as the Missoula Floods of geological legend, but it left a very similar record of scoured land, scattered boulders, huge waterfalls, and thick gravel bars.

Red Rock Pass near Downey, Idaho. The rocky hill in the center was part of the dam of sedimentary rocks which gave way 14,500 years ago and released the catastrophic Bonneville Flood.

View north from the dam area looking down one of the flood channels. On the left is a rocky outcrop of the original dam. On the right along the side of the channel is a gravel bar running parallel to the current direction.

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