Archive for June, 2012

Wooster’s Fossil of the Week: A mastodon tusk (Late Pleistocene of Holmes County, Ohio)

June 24th, 2012

This long and weathered tusk sits in a display case outside my office. It is from the American Mastodon (Mammut americanum) and was found many decades ago in Holmes County, just south of Wooster. A tooth found with it was a previous Fossil of the Week. Such tusks are rather rare because the ivory tends to disintegrate faster than tooth and bone. Our specimen is, in fact, hollow and held together by wires.
Above is a closer view of the proximal end of the tusk (the part closest to the face). You can see the hollowness and, curiously, that the ivory is charred. I used to tell students that the mastodon must have been hit by lightning, but I stopped when they took me too seriously!

This gives me a chance to mention a mastodon specimen I recently saw in a visit earlier this month to this famous place:
Monticello is, of course, the home of Thomas Jefferson, a Founding Father and the third president of the United States. Jefferson was a science enthusiast, and paleontology was one of his passions. He was fascinated with ancient life, and some have considered him the first American paleontologist. One room of the White House, for example, appears to have been devoted to his fossil bone collection.

Mastodons were particularly interesting to Jefferson because of an odd idea that was in vogue in France at the time. Georges-Louis Leclerc, Comte de Buffon, a famous French naturalist, wrote that “a niggardly sky and an unprolific land” caused life in the New World to be weak, small and degenerate. Life in North America was considered by the French to be quite inferior to that in Europe. Jefferson knew, of course, this was nuts. Having the bones of a North American elephant, as large or larger than any other elephants, would show the Frenchies how wrong they were. And Buffon eventually agreed, although he died before he could correct his books.
Above is a lower jawbone of Mammut americanum in Monticello. I wish I could have taken my own photograph, but this was not allowed. I’ve had to make do with one of their images online.

Curiously, Jefferson had one serious deficit when it comes to calling him a paleontologist. He apparently did not believe that species ever go extinct. When he dispatched Lewis and Clark on their expedition, for example, he expected them to find living mastodons deep in the American interior. Too bad they didn’t!

References:

Conniff, R. 2010. Mammoths and Mastodons: All American Monsters. Smithsonian Magazine, April 2010.

Semonin, P. 2000. American Monster: How the Nation’s First Prehistoric Creature Became a Symbol of National Identity. New York University Press, New York, 502 pages.

Thomson, K.S. 2008. The Legacy of the Mastodon: the Golden Age of Fossils in America. New Haven, Connecticut, Yale University Press.

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.

Memoirs of a Glacier

June 19th, 2012

Blog Post By Jennifer Horton

Lauren Vargo and I conducted our Senior I.S. field work in Glacier Bay National Park and Preserve, a beautiful park in the small town of Gustavus, Alaska.  GBNPP is a gigantic park that covers a span of 3.3 million acres of diverse landscape, from mountains, temperate rainforest, deep fjords, wild coastlines, and temperate rainforest.  We spent the majority of our time in Adams Inlet, a “small” cove located in the East Arm of the park.   Lauren and I soon learned that things in Alaska are usually much larger and farther away than they first appear!

A Google Earth Image of Adams Inlet, the location of our study

The tidal system of the Pacific Ocean dominates Adams Inlets.  On a daily basis the difference between low and high tides was over fifteen feet.  With water constantly flowing in and out of the bay, it was impossible for motorized boats to enter the inlet, so instead we kayaked!……with all our gear.

Lauren and I with all the gear

Not only was kayaking a great arm work out, it was a unique way to experience the wildlife of Glacier Bay.  We saw many birds, seals, porpoises, and even a seal lion as we paddled through the inlet.  On our first day in the field, we set up a base camp close to Muir Inlet, the location of the famous author John Muir’s cabin.  After working in this area for a couple of days, we packed up a modified camp and paddled deeper into Adams, with the tide of course!

Lauren and I just offshore in our expedition sized kayake

A large part of our fieldwork was to collect cores from ancient trees.  We hope to uses these cores, as well as some samples we gathered for radio carbon dating, to gain a better understanding of the glacial history of Adams Inlet.  Our hope is that the dates these trees will provide will correlate with the sediment and stratigraphy found in the various exposures we worked in.

Lauren coring a log in the field

After our twelve days of working in the field Lauren and I got to take a day off.  We took a boat tour up the West Arm of GBNPP.  On the tour, we got to see even more wild life from brown bears to mountain goats.  But, most importantly we finally got to see the impressive and dynamic glaciers of GBNPP.

Lauren and I in front of the Margerie Glacier

Going to GBNPP was an experience I will never forget.  Not only did I learn how to properly defend my self from bears, pitch a tent, core trees, and kayake, I learned what it takes to perform real geologic fieldwork. Senior I.S. has just started and I am already learning skills I will take with me after graduation.

I would like to give a special thanks to both Lauren Vargo and Dr. Wiles for making this experience so great, as well as the National Park Service and National Science Foundation for all their support.

From the Desert to the Rainforest: Heading to Alaska

June 19th, 2012

(Guest Blogger: Lauren Vargo)

From the desert to the rainforest, several other Wooster geologists, Dr. Greg Wiles, Jenn Horton, and myself, traveled to southeast Alaska. The main goal of the trip was to investigate Adams Inlet in Glacier Bay National Park and Preserve where we planned to use tree rings and stratigraphy to gain a more detailed geologic history of the Inlet.

However, our journey started (and ended) in Juneau with hikes up to and around Mendenhall Glacier. On our first day in the capital city, we took a leisurely hike up to the Glacier where we ate lunch near the terminus and saw first-hand glacial calving.

 

Jenn and I at the start of our hike up to Mendenhall Glacier

 

Jenn and I with the Wooster flag at Mendenhall Glacier

 

On our last day in Alaska, instead of hiking to the Glacier, we hiked up to the snow near tree line. We cored mountain hemlock trees for samples to send to a Swiss group to do isotope research, as well as to update our existing chronology.

 

Jenn and I above Mendenhall Glacier, hiking up to tree line

 

Coring a mountain hemlock tree

 

 

In between these excursions in Juneau, we traveled to Adams Inlet, our main destination, to research and collect data for our Independent Studies. We were lucky enough to have beautiful, sunny weather on our first day in the field.

 

A map of Glacier Bay National Park, with Adams Inlet marked with the red star

Jenn and I on our first day in Adams Inlet, enjoying the sun and clear view of the mountains

 

Watching the sunset on our first night in the field

 

Jenn and Dr. Wiles with all of our gear and the kayaks

 

In the Inlet, we looked at and took careful notes of the stratigraphy of several different valleys. We spent a good deal of time using the ice axe to clear off weathered and eroded sediment exposing varves (annual layers of clay and silt deposited in lakes) and other layers, usually of sand, gravel and glacial diamict.

 

Glacial lake varves we uncovered in one valley

 

 

Jenn and I sitting on top of glacial lake varves with deltaic sediment and mountains in the background

 

Dr. Wiles clearing off sediment to expose layers of varves and oxidized sand and gravel (also, notice the mud slickenlines from mudslides in the area)

 

Layers of clay alternating with sand and gravel exposed by the river cutting into the sediment

 

A closer view of clay layers within oxidized sand and gravel

 

 

In addition to the stratigraphy, in one valley we saw an amazing matrix supported rock flow.

Check out the video here.

And a second video here. 

 

Wooster’s Fossil of the Week: a long and skinny bryozoan (Upper Cretaceous of Wyoming and South Dakota, USA)

June 17th, 2012

Please say hello to Pierrella larsoni Wilson & Taylor 2012 — a new genus and species of ctenostome bryozoan from the Upper Cretaceous (Campanian-Maastrichtian) Pierre Shale of Wyoming and South Dakota. I imagine it as a graceful little thing spreading delicately through the dark interiors of baculitid ammonite conchs on a muddy Cretaceous seafloor. Above is a fossil of Baculites formed when sediment filled the shell and lithified. The shell itself dissolved away, leaving the internal mold  of rock (or steinkern) as a kind of cast of the interior. (But don’t ever call it a “cast”!) Pierrella larsoni encrusted the inside surface of Baculites and is thus preserved as a series of connected teardrops on the outside of the internal mold. The specimen is from Heart Tail Ranch, South Dakota, and the scale bar is 10 mm. (Baculites was described in an earlier Fossil of the Week post.)

My friend Paul Taylor (The Natural History Museum, London) and I had a wonderful field trip to South Dakota and Wyoming in June 2008. We were accompanied by my ace student John Sime (who is a spectacular field paleontologist) and greatly helped by the distinguished paleontologist and ammonite expert Neal Larson (Black Hills Institute of Geological Research), Bill Wahl (Wyoming Dinosaur Center), and Mike Ross, an avid amateur paleontologist in Casper, Wyoming. We also had assistance from Walter Stein (PaleoAdventures) and the enthusiastic and knowledgeable amateur paleontologist Jamie Brezina. You can see some images from our trip here.
The primary purpose of our expedition was to find and study Late Cretaceous bryozoans. Our paper describing this work has now appeared in a special volume on bryozoan research. The specimen above on the left is from Red Bird, Wyoming, and the one on the right is from the Heart Tail Ranch in South Dakota. The scale bars are 10 and 5 mm respectively.
Above is a typical example of the Pierre Shale exposures we worked with on this trip. This particular shot is from the Chance Davis Ranch in South Dakota, but they all looked pretty much the same. We crouched down and scanned miles of “outcrop” like this, picking fossils up from the ground.

Finding ctenostome bryozoans preserved like this is unusual. They did not (and do not today) have calcareous skeletons. These Pierre specimens were somehow preserved as the internal molds formed, most likely through some process of early cementation of the mud. I described this fossil fauna and its preservation in an earlier post from a GSA meeting.

Pierrella is named after the Pierre Shale; larsoni after our colleague Neal Larson. It is nice to have locked into the name direct reminders of that delightful summer under those big Western skies.

Reference:

Wilson, M.A. and Taylor, P.D. 2012. Palaeoecology, preservation and taxonomy of encrusting ctenostome bryozoans inhabiting ammonite body chambers in the Late Cretaceous Pierre Shale of Wyoming and South Dakota, USA. In: Ernst, A., Schäfer, P. and Scholz, J. (eds.) Bryozoan Studies 2010; Lecture Notes in Earth Sciences 143: 399-412.

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!

Wooster’s Fossils of the Week: dinosaur gastroliths (Jurassic of Utah, USA)

June 10th, 2012

These rounded stones are labeled in our collections as gastroliths (literally “stomach stones”) from Starr Springs near Hanksville, Wayne County, Utah. I’m featuring them this week in honor of our Utah Project team working right now in the baking Black Rock Desert near Fillmore, Utah.

From their reported location, these stones are likely out of the Summerville Formation (Middle-Upper Jurassic) and, in another plausible supposition, probably from some sort of dinosaur. Sometimes we just have to trust the labels on our specimens, at least for educational purposes!

My friend Tony Martin recently wrote an excellent blog post on gastroliths, so I won’t repeat his insights here. The general wisdom is that these stones were consumed by herbivorous dinosaurs to aid in their digestion. They would have lodged them in the equivalent of a gizzard and used them to grind their food, much like modern birds. (And yes, dinosaurs were birds themselves.) Gastroliths usually have a resistant lithology to be useful as grinders. The gastroliths above are chert, one of the hardest rock types.

Identifying gastroliths correctly is a bit of a challenge if you don’t find them inside a dinosaur skeleton. The most common indicators are that they are very smooth, are in a location where they were unlikely to have been transported inorganically, and are of a lithology unlike the surrounding rock (“exotics” as geologists like to call them). Still, even with all these criteria met, we must be a tad suspicious if we didn’t find them associated with dinosaur bones. I would never, for example, buy a gastrolith in a rock shop. Without context, it could be just a stream-worn stone. I’m trusting the label on ours that we have the real deal!

References:

Stokes, W.L. 1987. Dinosaur gastroliths revisited. Journal of Paleontology 61: 1242-1246.

Wings, O. 2007. A review of gastrolith function with implications for fossil vertebrates and a revised classification. Acta Palaeontologica Polonica 52: 1-16.

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