Wooster’s Fossils of the Week: An oyster reef from the Middle Jurassic of southwestern Utah

September 29th, 2017

It was a pleasure to pull this massive specimen out of the cabinets, where it had been sitting for more than 20 years. It is a small reef of the oyster Liostrea strigilecula (White, 1877) from the Carmel Formation (Middle Jurassic) near Gunlock, southwestern Utah. It is out of storage because I’m returning to this section in Utah with students this summer to begin fieldwork again. The rocks and fossils are fascinating, and it is time someone looked seriously at them again.

A closer look at these little oysters shows how they could construct such a tight, nearly seamless structure. Each oyster grew in a cup-like fashion (first pointed out by Tim Palmer) so that they nestled together rather than overgrowing each other. These same oysters in this same locality also formed the famous oyster balls (ostreoliths). These reefal equivalents grew on carbonate hardgrounds, which are abundant in the Carmel Formation.

Liostrea strigilecula was named by Charles Abiathar White (1826-1910) as Ostrea strigilecula in 1877. White was an American paleontologist and geologist who did considerable work on midwestern and western North America. He was born in Massachusetts and worked in Iowa as the state geologist from 1866 to 1870. He returned east to teach at Bowdoin College for a couple of years, and then he joined the United States Geological Survey from 1874 into 1892. In 1895 he became an associate in paleontology at the United States National Museum. White was one of the first fellows of the American Association for the Advancement of Science, one of the first members of the Geological Society of America, and he was elected a member of the National Academy of Sciences in 1889. Abiathar Peak in Yellowstone National Park was named after him. A more thorough biography can be found at the link.

I’m looking forward to seeing these beautiful oysters in the field again!

References:

Bennett, K. 2017. White, Charles Abiathar. The Biographical Dictionary of Iowa. University of Iowa Press, 2009. Web. 19 September 2017

Nielson, D.R. 1990. Stratigraphy and sedimentology of the Middle Jurassic Carmel Formation in the Gunlock area, Washington County, Utah. Brigham Young University Geology Studies 36: 153-192.

Taylor, P.D. and Wilson, M.A. 1999. Middle Jurassic bryozoans from the Carmel Formation of southwestern Utah. Journal of Paleontology 73: 816–830.

Wilson, M.A. 1998. Succession in a Jurassic marine cavity community and the evolution of cryptic marine faunas. Geology 26: 379–381.

Wilson, M.A. 1997. Trace fossils, hardgrounds and ostreoliths in the Carmel Formation (Middle Jurassic) of southwestern Utah, in Link, P. and Kowallis, B., eds., Mesozoic to recent geology of Utah, Brigham Young University, v. 42, p. 6–9.

Wilson, M.A., Ozanne, C.R. and Palmer, T.J. 1998. Origin and paleoecology of free-rolling oyster accumulations (ostreoliths) in the Middle Jurassic of southwestern Utah, USA. Palaios 13: 70–78.

Exploring the Geosciences at Zion National Park

July 10th, 2017

Zion National Park – Dr. Wiles and I are directing a 5-week undergraduate research project through the Keck Geology Consortium‘s Gateway Program. The Gateway Program has two goals: engage the students in an authentic research experience while exploring the intersections between the geosciences and society. Three weeks into the project, the students have collected tree cores and lava samples in Alaska and Utah, respectively, and are hard at work processing those samples in the Wooster labs. In the meantime, the students have explored the geosciences by talking with geoscience professionals and visiting locations like the Utah Geological Survey and Zion National Park. Here are Team Utah’s reflections on the intersections between geoscience and society, in their own words:

Pa Nhia Moua (’20, Carleton College)

On June 27th, 2017, Team Utah from the Keck Geology Consortium visited Zion National Park. Before Keck, I had never visited a national park before, so I was really excited to see how a national park differed from a “regular” city/town park. To my surprise, when we first arrived, I felt like I was at Disney world again or at the state zoo (Minnesota Zoo). As we continued into Zion, I realized how commercialized Zion was. Gift shops greeted customers on their way in and out, park rangers available for information (but to me they seemed like tour guides), and the long line of people (waiting for shuttles). The amount of commercialization astounded me as I was not aware how popular a national park could be. After splitting up, part of Team Utah traveled to venture the Riverside Walk, where we had our lunch. We sat on the riverbank, on rocks and trees, under the shade. As I ate, I found myself often wondering about the formation of the landscape. I wondered how much things had withered away, and what was originally there and what had come later. After lunch, we walked the riverside path and we continued onto the Narrows. It was here where I really got a good look at how other people interacted with the landscape and everything else around them. Majority of the people would look up at the sky in admiration of the stone walls that created the “narrows” and kept the formation of the river. But, as I ventured deeper into the Narrows, I noticed that the only time people took in the scenery was in the beginning. Majority of the people interacted with the water, as they were trying to keep from falling while catching up with their groups. I feel that because of the Keck Geology Consortium program, my experience at Zion has been enriched by the knowledge I have acquired (while in the program). Since my participation in the program, I have become more conscience about the world around me. I wonder more about the history of where I go and what I see. Because of such thoughts, I feel that my knowledge deepened my meaning and experience at Zion.

Pa Nhia stands in the Narrows in Zion National Park.

Sam Patzkowsky (’20, Franklin and Marshall)

Zion National Park is one of the most beautiful places that I have visited in the 19 years I have been on this Earth.  The geology of the park was unlike anything I have ever seen before and I was blown away by the amount of people who were at the park.  Geology plays a huge role in the National Park Service; since there are many national parks that are centered around geology.  What astounds me is that people know how appealing these parks are to people and that there are those who know take advantage of this and make a living of it.  When I think of the word “tourism,” I think of hotels on white sand beaches during prime summer hours.  This, however, isn’t the case with a place like Zion National Park.  There are the typical hotels and inns located in the town just outside of the park, but there are also shops that try to take advantage of people’s curiosity about the rocks and the geology.  I am really happy to see this because it means that if a shop can sell someone a cool looking rock, then maybe they’ll start to ask questions like: “how did this form?” “what is this made up of?” “where can I find things like this?”.  If even one person’s life changes because of looking at these tourist shops, I will be forever grateful because the seed of geology is being planted in their mind and hopefully it’ll grow into something breathtaking.  Tourism is something that is crucial to the interaction between the public and geology and I hope it can help change lives for the better.

Team Utah at the Zion National Park entrance.

Emily Randall (’20, College of Wooster)

One of the biggest things I noticed at Zion National Park was what seemed to be the lack of interest in the geology. When people arrived at each location they would glance at the features surrounding them a few times before proceeding to a task that then took all of their attention. Where I was, this was either playing in or wading through the river, but I’m not sure about other locations. Luckily, whether people realized it or not, these types of tasks forced them to interact with the geology around them. I also appreciated that the Parks Services had audio about the park and its geologic features playing on the bus, which some people listened to but a lot seemed to talk over. I’m not sure what could be done to make the, what I see as impressive, rocks beat out the water on a scorching summer day like the one we visited during, but I hope my impression was skewed since I visited the river. Though, this was to view the impressive narrows and the striking cliffs as opposed to play in the water.

Hiking the Narrows at Zion on a 100+ degree day.

Madison Rosen (’19, Mt. Holyoke)

Utah is a beautiful state filled with many different types of geology, from 20 feet high dinosaurs to brine shrimp that are less than a inch long. During my weeklong stay in Utah, I was able to experience most of what it was famous for. This included, Zion National Park, Salt Lake, Natural History Museum of Utah and the Geological Survey of Utah. My favorite was Zion National Park, because of its enormity and beauty. At Zion National Park the erosional effects of water on sandstone was easily seen, but the average park goer was not focused on the geology of the park. Instead thousands of people would stand in a theme park like line to get the perfect picture on top of these geological landforms. On the shuttle bus, a quick description of how Zion was developed was announced, but not everyone was paying attention to the 30 second long segment. Unlike other parks that I have been to, many of the people were rushing to get from one spot to the next, making for an almost chaotic atmosphere at times on the popular trails. The sheer number of people was overwhelming, but I had a wonderful time seeing enormous sedimentary structures and learning about Zion. Geology and society interact minimally, but not limited to if the visitor wants to learn more by asking employees of the park. People who visit the Natural History Museum are more open to learning how things happened in an interactive setting. While at the Geological Survey certain groups or companies go there with the purpose of learning about a particular core. The audience’s intention of visiting a certain place really determines how much knowledge that they will gain from that experience. It was really special to get to see the geological features of Black Rock Desert, Zion National Park, Salt Lake and what the Natural History Museum of Utah and Geological Survey of Utah does to interact and involve the public.

Team Utah learning about the cores stored at the Geological Survey of Utah.

A picture of Zion National Park on the 100-degree day Team Utah visited.

Addison Thompson (’20, Pitzer College)

How does geoscience intersect with society?

Water is one of the most basic needs to a human.  When examining a map, it is easy to recognize that most major cities have been constructed in close proximity to a substantial water source due to the ease of access.  When visiting my relatives in the small rural town of Biglerville, PA, I was never quite sure how they acquired their water.  They are near no river nor suitable water source, yet water flows from their tap just as it does in my home, Baltimore.  The answer for their water source is a well.  Far beneath their town is an aquifer, which can be tapped for water.  The aquifer is usually made of sandstone and water can remain in the sandstone because of the stone’s high porosity.  To create the well, a pipe system is drilled into the porous sandstone and the water in extracted.  The geologic phenomenon of the creation of an aquifer enables my cousins to live in their small rural town and sustains thousands of other towns which lay far away from usable surface water sources.  This usage of aquifers as a water source has allowed people to move where they please and into more remote places previously believed to be uninhabitable because of the lack of water, however it has always been just below us.  The presence of aquifers has helped humanity spread to the corners of the world.

While in Zion, Sam Patzkowsky and I witnessed the aquifer process from an interesting vantage point.  Usually the sandstone that comprises an aquifer is underground, however during our hike, there were sandstone slabs above ground in which it could be seen that water was seeping through.  Most notable of these being weeping rock, a sandstone block from which water seeps thus personifying weeping.

 

 

The conclusion of an excellent field season

June 28th, 2017

Guest Bloggers: Addison Thompson (’20, Pitzer College), Pa Nhia Moua (’20, Carleton College), and Sam Patzkowsky (’20, Franklin and Marshall) write about our last day of field work

6.26.17  Despite the often inhospitable conditions of the Black Rock Desert, the cohesion of team Utah made the scientific process enjoyable.  After the immediate success of the first day, it was given that the group would surpass any benchmark that Dr. Pollock had imagined.  The constant willingness for members to go above and beyond what was necessary to advance the mission in the Black Rock Desert was indicative of the excitement the group derived from the task at hand.

Team Utah with cinder cones in the background.

Although sweating, sore arms, and general discomfort at this point was par for the course, the final day in the field was bitter sweet.  The group ended on a high note, collecting a total of seven samples on the day.  Dr. Pollock said, “finding a suitable piece of pahoehoe is like finding a needle in a haystack”, so the group found two.  In addition to the pahoehoe samples, numerous samples were found that were suitable for Varnish Microlamination testing.  With the day complete, the group left the four cinder cones and their vast, puzzling lava flows in search of petroglyphs that were said to be nearby.  These were never found.  The ride back to camp was quiet, people were either staring out the window at the expansive Utah landscape or with their heads rocked to the side catching some z’s.

Pa Nhia Moua Carleton College ’20 demonstrating proper enthusiasm whilst in the field.

Pa Nhia Moua
Carleton College ’20 Member of Team Keck
As we ventured on our last day in the field, we were determined to make up for our day “off the field”. With pride and gratitude, the team worked hard to use all information we learned on the field to search for suitable samples. Hurrah to Team Utah! The seven samples we collected in one day shows our spirit, our optimism, and our growth of knowledge! And as a plus, a massive lava tube (~15-20 m tall) was discovered, and offered us wonderful protection from the shining rays of the sun. Great job team! Now, may luck and knowledge be with us in the labs!

“I could have sworn we parked the car over there.”

Sam Patzkowsky

Franklin & Marshall College ’20

As our trip in Utah comes to a close, I am flooded with all the unique and rewarding experiences that occurred.  One of these experiences that stuck out to me was from our first day in the field; right after lunch we had split up into groups to try and understand what the heck was going on in the immediate area.  My group consisted of me and Addison Thompson (Pitzer College ’20), and as we trudged off away from the other group, it hit me, I had known this kid for all of three days and suddenly we were thrust into a position to work together to attempt to understand the volcanics of this field, unknowing if we’d have a great dynamic or a poor one.  As this work continued, I knew that even if we had different personalities, geology is a field where people can set aside their differences, whatever they may be, and just nerd-out about rocks.  It is truly a unique field of study and one that I am excited to continue working and studying in.  Oh, and Addison is one heck of a group partner, in case you were wondering.

Emily Randall ’20 the College of Wooster collecting a righteous sample of Pahoehoe with colleagues looking on eagerly.

Our resident photogenic individual, Sam Patzkowsky, Franklin & Marshall ’20 beating the heat with a crispy apple.

Team Utah Takes to the Field

June 26th, 2017

Guest Blogger: Addison Thompson (’20, Pitzer College) writes about our first 3 days of field work.

6.23.17 For the Utah group, the first day in the field was daunting yet rewarding as our intrepid group of young geologists made themselves acquainted with the Ice Springs Volcanic Field.  The Ice Springs Volcanic Field, located in the Black Rock Desert of Utah, is home to many old cinder cone volcanos that currently lay dormant.  In the past the cinder cones were active volcanos, spitting and oozing lava.  The lava flows have since cooled and currently take the form of basaltic rocks spilling out from four primary cinder cones, Miter, Crescent, Pocket and Terrace.

The day began at 7:15am with breakfast, after which foods were divided for lunch, sandwiches were assembled, and packs were equipped and made field ready.  Everything was ready, as was the team and off the Utah group went to the field site, arriving just after 9am.  After days of anticipation, stepping out of the car face to face with what the group had read so many articles and papers about was magical.  In no time, the group  was on their way, climbing up the service road, and eventually up the cinder cone named Miter in order to get a lay of the rocky land.

Team Utah atop the Mitre cinder cone

The terrain comprised uneven, sharp, basaltic rocks and was difficult to traverse, but the group managed.  After climbing Miter, the next move was to follow the presumed Miter lava flow path which eventually emptied into a flat basin, an area interpreted to be where a lava flow once pooled.  A good section of pahoehoe, a ropy formation of a basaltic rock, was quickly identified, and its sample was taken.

Sam Patzkowsky (’20 Franklin and Marshall College and Team Keck member) dislodging a piece of Pahoehoe to be used as a sample.

With the success of the pahoehoe find, it was time for lunch.  Shade was hard to come by, so people did their to take refuge from the incessant beating of the sun.  Water was a must.  After lunch the group split up in the attempt to identify the Mitre/Crescent lava flow boundary, not an easy task.  Regardless of the difficulty, progress was made and we ended the day with promising evidence that could work towards our hypothesis.  After a long first day in the field, morale was high but energy was very low; dinner was a welcomed sight.

6.24.17 Waking up on the second day was a breeze.  The group had a plan in mind and very little was left to chance.  First on the chopping block was a visit to the Carbon-14 dating site followed by accessing the area that is believed to house the Miter/Crescent boundary.  Sadly the Carbon-14 dating site was only accessible by a private road, so that idea was nixed.  Next up was entering the lava flows from the north west side via a rarely traveled dirt access road.  The going was bumpy but eventually the car made it to a suitable stopping point.  The walk to the toes (the extent) of the lava flows was a brief flat jog that took minutes; however, the real challenge began when it became necessary to climb the lava flows in order to press on.   Over the course of the trip, the sharp basaltic rocks have claimed many a causality, so the group favored precision over speed.  In searching for Miter/Crescent boundary evidence, it was impossible to ignore other important geologic occurrences.  One of these interesting being a large boulder, about 8ft. tall, comprised of lava bombs that must have been part of a cinder cone that rode a lava flow to the edge.

Measuring a boulder that was transported to its current location by a lava flow.

This helped give an idea about the power of the flows.  Measurements of the boulder were taken along with photos for reference.

As the group pressed deeper into the flows they began to notice an accumulation of large basaltic slabs sticking out of the ground in all directions and angles.  Dr. Pollock noted that information about these slabs could be important towards our ultimate goal, so slab measurements needed to be taken, twenty in all.  Taking a slab measurement consisted of noting the coordinates of the hunk of rock, its width in centimeters, taking photos of the slab under examination, and lastly noting the size of the vesicles (holes created by the expulsion of gas during the cooling process).

Two members of Team Keck measuring a slab’s width.

The reward was lunch and maybe shade.  Luckily, shade was easier to find than the day before and the group crouched, laid, and sprawled under the angled rocks.  But like all good things, lunch came to an end.  Regardless of the heat, the group was always eager for more field work so they decided to push farther east in search of a boundary that had previously been visible from a birds eye map.  At the boundary, samples were to be taken for geochemistry analysis.  Eventually the boundary was reached and the samples were taken.  After a efficient day in the field it was time to turn around.  Dinner was burgers and everyone went to sleep soon there after.

6.25.17  The third full day in Utah did an excellent of of testing everyones nerves.  A special thanks goes out to Dr. Pollock for her cool disposition in the face of a turbulent situation.  The day began as a normal day does with breakfast, then lunch packing, and finally going over the mission of the day.  The catch was that the back right tire of the car that didn’t want to go along with the plan.  Minutes away from the field site the low tire pressure sign flashed on the dashboard so the group turned around and went to go get air for the noticeably deflated tier.  However the issue was that the tire had a puncture, not that it simply had low pressure.  With the spare now on the car, there was no backup and driving over rocky terrain without a spare tire is a disaster waiting to happen, so the call was made to switch rental cars.  This required Dr. Pollock driving the rental up to the Salt Lake Airport to exchange cars, a two hour trip both ways.  This exchange took a majority of the day so there was sadly no time left for field work.  This was definitely a disappointment, but the group handled it well.  The day was instead spent relaxing, uploading information from the field and doing any other minor housekeeping chores.  Emily Randall (’20 College of Wooster and Team Keck member) created a map locating every coordinate where a sample had been taken.  Finally towards the end of the day a few members went on a hike along an ATV path that wound towards the mountains behind the camp site.

A panoramic taken from the hike.

Although no field work was conducted it was a productive day.

 

A Strong Start to the 2017 Keck Gateway Project

June 22nd, 2017

Guest Blogger: Addison Thompson (’20 Pitzer College and Team Keck Member)

The 2017 Keck Gateway Team.

Amid our first official day at the College of Wooster, spirits were high as we embarked on the five week Keck Gateway Project.  The Gateway Project encompasses two different scientific enquiries which will span three states; Ohio, Utah, and Alaska.  The goal of the project centered in Utah is to determine the age of geologically young lava flows (now igneous rock) in the Ice Springs Volcanic Field of central Utah in order to add another piece to the unsolved puzzle of the Earth’s geologic history.  The goal of the project centered in Alaska aims to gain a better idea of why Cedar trees in Juneau are in decline.  The information gained from the students working in Alaska will help pinpoint specific environmental factors that are adversely affecting ecosystems, trees in particular.  This portion of the project is one week long.

Evidence of a tree core.

Once the data from the Utah and Alaska field sites are complied, both teams will return to the College of Wooster to complete lab tests in order to answer each respective hypothesis. This portion of the project is roughly three weeks long.  The participants of the project also have the opportunity to attend and present the findings of their research at the GSA’s (Geological Society of America) annual conference in Seattle in mid-October.

The first full day of the project was a beautiful one and we dove into the topic material with gusto.  We began at 9am in the geology department which is located in Scovel Hall and had a discussion about the rules of authorship and the details of what mentoring means with Dr. Pollock and Dr. Wiles.  Following that, details for the field work trips (Utah and Alaska) were coordinated and supplies like rock hammers and chisels were evenly distributed.  At that point it was time to break for a much needed lunch.  The Keck group met back at Scovel Hall around 1:30, just in time for a jaunt around the Oak grove led by Dr. Wiles, during which the group cored three trees to determine their age.

The processing of coring trees involves inserting a hollow drill into the tree, then removing the sample of the tree located in the hollow drill.

An excited Team Alaska member extracts her tree core.

The Alaska team will use this method hundreds of times in order to determine the health of trees in a large area.  With the first day complete, our group looks forward to strengthening our bonds and embarking on our geology research.

On the second day, the Utah group and the Alaska group split to their respective labs to discuss the minutia of the trips.

The Utah group examined basaltic rocks from the Black Rock Desert, the location where they will be conducting their fieldwork.

These rocks had previously been dated via two techniques: one being Varnish Microlamination (VML) which aims to date the rocks by measuring the coating on rock surfaces, the other being Cosmogenic Nuclide Dating which measures the accumulation of radioactive isotopes in the surfaces of the lava flows.

Meanwhile the Alaska group learned more about tree coring, a practice they will become very familiar with during their stay in the last frontier.

This concluded our work for the day, and we broke for lunch.  The rest of the day was spent preparing for our arduous journeys to the field sites the following morning.  We went shopping to stock up on various items for the trips.  The day came to a conclusion with a delicious dinner and some frisbee outside Douglas Hall.

Much to their chagrin, the Alaska group was departing the College of Wooster at 4am on the third day.  The Utah group was given a more lenient departure time, 6am, because their destination was 2,113 miles closer to the College.  There were no issues rising bright and early and both groups headed to Cleveland Hopkins Airport with anticipation of the journey ahead of them and slightly weary eyes.  To make matters more interesting for the Alaska group, their travel plans routed them through Dallas Fort Worth…not quite in their desired direction but they were sports nonetheless. And so the day went, a travel day.  The Utah group touched down in Salt Lake City in the mid afternoon and began the two hour drive to the town of Fillmore, only stopping once for a much needed dinner.  Eventually the group made it to their campground and settled in their cozy cabins.  After a long day of travel and two hours lost, a rest is what the doctor ordered.  As of writing this, the Alaska group is currently still in transit to Juneau.  Tomorrow marks the first official day of field work in the Black Rock Desert for the Utah group and there is an excited fervor hanging in the air.  All the tools and measurement devices are prepped and ready to go.

 

 

 

 

Team Utah 2015

August 6th, 2015

Guest bloggers: Julia Franceschi and Mary Reinthal

What do you get when you have zero cloud coverage, 90-degree heat, and a desert? Aside from the start of a bad joke, you get a snippet of the College of Wooster geology’s 2015 expedition to Black Rock desert Utah. It was here that some of the College’s senior geology students—Krysden Schantz, Michael Williams, and Kelli Baxstrom—collected some sunburns and samples for their Senior Independent Studies. These research projects range anywhere from trying to figure out the date of the lava flow to mechanisms of emplacement (e.g., channelized vs. inflated flows). Some of the students that went, however, went because they were able-bodied field assistants who could handle the heat. Geology major Julia Franceschi said this about her field assisting experience:

“Utah was extremely hot and there were some days (and by some days I mean everyday) where 3 liters of water were not enough. But we managed to get a lot of good data, even though my boots took a beating (R.I.P). ”

Chloe Wallace and Julia Franceschi use the Trimble GPS to make cm-scale measurements of the topography.

Chloe Wallace and Julia Franceschi use the Trimble GPS to make cm-scale measurements of the topography.

When the plane finally landed in Salt Lake City, Utah, a 2 ½ hour drive took the crew to Fillmore, the location of their field site. The first day, Friday, started around 11AM, but the crew learned quickly that the earlier they started, the less intense the sun (and heat) was.

Team Utah meeting to distribute equipment and plan the field day.

Team Utah meeting to distribute equipment and plan the field day.

Like for most groups, the first day was devoted as a get-accustomed-to-the-field day, that entailed some reconnaissance and exploration. The rest of the week was spent doing eight hours a day of research and studies. According to Dr. Meagen Pollock, walking on a’a is “nonsense” and more often than not, each day was faced with new challenges. Chloe Wallace and Julia conducted high resolution GPS location and elevation data. Dan Misinay took photographs and helped Krysden conduct transects to record vegetative cover. Michael and Kelli spent most of their days mapping the area and attempting to understand volcanic features. Some days, however, were graced with the occasional snake or rainbow to change up the scenery. It was a successful trip.

One of our lizard friends.

One of our lizard friends.

A snake friend, warming itself in the morning sun. Photo credit: Dan Misinay

A snake friend, warming itself in the morning sun. Photo credit: Dan Misinay

Kelli and Dr. Judge measuring striae.

Kelli and Dr. Judge measuring striae.

Krysden is in her element among the lavas.

Krysden is in her element among the lavas. Photo Credit: Dan Misinay

Contemplating lava emplacement clearly brings joy to Michael.

Contemplating lava emplacement clearly brings joy to Michael. Photo Credit: Dan Misinay

Dan helps Krysden with her vegetation survey.

Dan helps Krysden with her vegetation survey.

We were treated to a double rainbow over our field site after a light sprinkle in the desert.

We were treated to a double rainbow over our field site after a light sprinkle in the desert.

And a show of wild flowers! Photo Credit: Kelli Baxstrom

And a show of wild flowers! Photo Credit: Kelli Baxstrom

Team Utah proudly representing Wooster Geologists!

Team Utah proudly representing Wooster Geologists!

Wooster’s Fossil of the Week: Star-shaped crinoid columnals from the Middle Jurassic of southern Utah

February 27th, 2015

Isocrinus nicoleti Kane County 585Just a quick Fossil of the Week post. Above we see isolated columnals (stem units) of the crinoid Isocrinus nicoleti (Desor, 1845) found in the Co-Op Creek Member of the Carmel Formation (Middle Jurassic), Kane County, southern Utah. Greg Wiles recently received them as part of a donation to our department collections. They have such perfect star shapes that I had to share them here. For the full analysis, see my previous entry on columnals like these preserved in a limestone from the same location.

References:

Baumiller, T.K., Llewellyn, G., Messing, C.G. and Ausich, W.I. 1995. Taphonomy of isocrinid stalks: influence of decay and autotomy. Palaios 10: 87-95.

Tang, C.M., Bottjer, D.J. and Simms, M.J. 2000. Stalked crinoids from a Jurassic tidal deposit in western North America. Lethaia 33: 46-54.

Wooster’s Fossil of the Week: An early bryozoan on a Middle Ordovician hardground from Utah

October 10th, 2014

ORBIPORA UTAHENSIS (Hinds, 1970) 072014Last week I presented eocrinoid holdfasts on carbonate hardgrounds from the Kanosh Formation (Middle Ordovician) in west-central Utah. This week we have a thick and strangely featureless bryozoan from the same hardgrounds. It is very common on these surfaces, forming gray, perforate masses that look stuck on like silly putty. Above you see one on the left end of this hardground fragment. (The circular object to the right is another eocrinoid holdfast.)
Kanosh bryo eo 072014Here is a closer view of the bryozoan, again with one of those ubiquitous eocrinoids encrusting it. The holes are the zooecial apertures. Each zooecium is the skeletal component of a living bryozoan individual (zooid). Note that the walls are thick and granular between the zooecia. All the zooecia look pretty much the same, and there are no other structures like spines, pillars or maculae. This is about as simple as a bryozoan gets.

It is impossible to be certain without a thin-section or acetate peel showing the interior, but I’m pretty sure this Kanosh bryozoan is Orbipora utahensis (Hinds, 1970). It matches fairly well the description in Hinds (1970), who named it Dianulites utahensis, and it fits within the redescription by Ernst et al. (2007).

Several years ago we would have called this a trepostome bryozoan and left it at that. These are, after all, the “stony bryozoans” with thick calcite skeletons and long zooecia. However, the group to which Orbipora belongs is unusual because they have no polymorphs (small zooecia different from the primary zooecia) and have granular skeletal textures rather than laminated. We think the granular walls may be because the original skeletons were made of high-magnesium calcite that later altered to low-magnesium calcite and dolomite, losing details of the microstructure. Orbipora is thus in an as yet undescribed new order of bryozoans. [Update: See comment below from Paul Taylor.]

The Kanosh hardgrounds and their attaching faunas are important in geological and biological history because they are telling us something about the geochemical conditions of the seawater when they formed. We think this was a peak time of Calcite Seas, when low-magnesium calcite was a primary marine precipitate and carbon dioxide levels were high in the atmosphere and seawater. Hardgrounds would have formed rapidly because of early cementation, and aragonite and high-magnesium skeletons would have altered soon after death. The abundant Kanosh communities and substrates are critical evidence for these conditions that were superimposed on the Great Ordovician Biodiversification Event (GOBE). We thus have a delightful combination of seawater geochemistry (and, ultimately, the tectonics that controls it) and evolution intertwined in the history of these rocks and fossils.

References:

Ernst, A., Taylor, P.D. and Wilson, M.A. 2007. Ordovician bryozoans from the Kanosh Formation (Whiterockian) of Utah, USA. Journal of Paleontology 81: 998-1008.

Hinds, R.W. 1970. Ordovician Bryozoa from the Pogonip Group of Millard County, western Utah. Brigham Young University Research Studies, Geology Series 17: 19–40.

Marenco, P.J., Marenco, K.N., Lubitz, R.L. and Niu, D. 2013. Contrasting long-term global and short-term local redox proxies during the Great Ordovician Biodiversification Event: A case study from Fossil Mountain, Utah, USA. Palaeogeography, Palaeoclimatology, Palaeoecology 377: 45-51.

Wilson, M.A., Palmer, T.J., Guensburg, T.E., Finton, C.D. and Kaufman, L.E. 1992. The development of an Early Ordovician hardground community in response to rapid sea-floor calcite precipitation. Lethaia 25: 19-34.

Wooster’s Fossils of the Week: Eocrinoid holdfasts on a Middle Ordovician hardground from Utah

October 3rd, 2014

Kanosh Hardground 072014 smBack in the late 1980s and early 1990s, several students and I did fieldwork in the Middle Ordovician Kanosh Formation in west-central Utah. One year we were joined by my friend Tim Palmer of the University of Aberystwyth. Together, Chris Finton (’91), Lewis Kaufman (’91), Tim and I put together a paper describing the carbonate hardground communities in this remarkable formation (Wilson et al., 1992). At top is an image of one of the surface of one of these hardgrounds. It is covered with holdfasts of rhipidocystid eocrinoids, a kind of primitive echinoderm.
Fossil Mountain UtahMost of the hardgrounds we studied in the Kanosh Formation were found here at Fossil Mountain near Ibex, Utah. (If you want to consider Ibex a place, at least.) It was a beautiful place to work, and it is still highly productive for geologists and paleontologists (see Marenco et al., 2013, for the latest investigation).

Kanosh eocrinoid 2The encrusters on the Kanosh hardgrounds are dominated by two groups: bryozoans (which we’ll highlight next week) and stemmed echinoderms (this week’s subject). The echinoderms are represented by thousands of these small attachment structures called holdfasts. The stem of the echinoderm was attached here to the hardground. The entire skeleton of the echinoderm, including the hardground, is made of low-magnesium calcite, so they are very well preserved. Surprisingly, the hardground communities in the Kanosh have very few sponges or borings.

Kanosh eocrinoid 3 072014The holdfasts come in a few varieties with subtle morphological differences. Here we have one with a tri-radiate center.

Kanosh eocrinoids 1Sometimes the holdfasts blended together on the hardground surface, which was probably the result of competition for attachment space. Note the tri-radiate centers.

Mandalacystis diagramFrom a few plates we found, it appears that the rhipidocystid eocrinoid holdfasts are from a creature like Mandalacystis, which is pictured above from Figure 1 of Lewis et al. (1987). We can’t tell for certain without more of the skeleton, but the holdfasts are very similar to what has been described for the genus.

These Middle Ordovician hardgrounds were formed at an interesting time in the chemistry of the oceans and the development of marine invertebrate faunas. More on that next week!

References:

Ernst, A., Taylor, P.D. and Wilson, M.A. 2007. Ordovician bryozoans from the Kanosh Formation (Whiterockian) of Utah, USA. Journal of Paleontology 81: 998-1008.

Lewis, R.D., Sprinkle, J., Bailey, J.B., Moffit, J. and Parsley, R.L. 1987. Mandalacystis, a new rhipidocystid eocrinoid from the Whiterockian Stage (Ordovician) in Oklahoma and Nevada. Journal of Paleontology 61: 1222-1235.

Marenco, P.J., Marenco, K.N., Lubitz, R.L. and Niu, D. 2013. Contrasting long-term global and short-term local redox proxies during the Great Ordovician Biodiversification Event: A case study from Fossil Mountain, Utah, USA. Palaeogeography, Palaeoclimatology, Palaeoecology 377: 45-51.

Wilson, M.A., Palmer, T.J., Guensburg, T.E., Finton, C.D. and Kaufman, L.E. 1992. The development of an Early Ordovician hardground community in response to rapid sea-floor calcite precipitation. Lethaia 25: 19-34.

Wooster’s Fossil of the Week: A faulted oyster ball from the Middle Jurassic of Utah

July 25th, 2014

Split oyster ball 062914I’m returning this week to one of my favorite fossil types: the ostreolith, popularly known as the “oyster ball”. These were lovingly described in a previous blog entry, so please click there to see how they were formed and some additional images. They are found almost exclusively in the Carmel Formation (Middle Jurassic) of southwestern Utah.They are circumrotatory (a fancy word for “rolling around while forming”) accumulations of small cup-like oysters along with minor numbers of plicatulid bivalves, disciniscid brachiopods, cyclostome bryozoans (see Taylor & Wilson, 1999), and mytilid bivalves that drilled borings known as Gastrochaenolites. They are nice little hard-substrate communities originally nucleated on bivalve shells (Wilson et al., 1998).

oyster ball close 062914Here is a close view of the oyster valves on the outside of the ostreolith. They are attached to similar valves below them, and it is oysters all the way to the center.

What is special about our specimen here is that it managed to obtain a fault right through its center! The chances of this happening are slim, given that they are relatively rare in the rock matrix. The faulting was probably during the Miocene related to a “left-lateral transfer zone that displaces north-south–trending crustal blocks of the eastern Basin and Range Province to the west” (Petronis et al., 2014, p. 534). This is an interesting tectonic region between the Basin and Range Province and the Colorado Plateau.

Slickenfibers 062914A close view of the fault surface shows it is a striated slickenside. The striations (called slickenlines) are parallel to the direction of movement, not that we have to guess when we look at the ostreolith itself. There are also calcitic deposits here formed during faulting called slickenfibres. These elongated crystals have tiny step-like breaks in them that show the actual direction of movement.

Another nice specimen combining paleontology and structural geology.

References:

Petronis, M.S., Holm, D.K., Geissman, J.W., Hacker, D.B. and Arnold, B.J. 2014. Paleomagnetic results from the eastern Caliente-Enterprise zone, southwestern Utah: Implications for initiation of a major Miocene transfer zone. Geosphere 10: 534-563.

Taylor, P.D. and Wilson, M.A. 1999. Middle Jurassic bryozoans from the Carmel Formation of southwestern Utah. Journal of Paleontology 73: 816-830.

Wilson, M.A., Ozanne, C.R. and Palmer, T.J. 1998. Origin and paleoecology of free-rolling oyster accumulations (ostreoliths) in the Middle Jurassic of southwestern Utah, USA. Palaios 13: 70-78.

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