Geology and art meet with a ceramic creation from the Cretaceous extinctions

February 16th, 2012

In August 2010 I had a fantastic geologic field trip to the tunnels of Geulhemmmerberg, The Netherlands, to see an unusual exposure of the Cretaceous-Paleogene boundary. There I collected a fist-sized sample of the famous boundary clay, which is found in a variety of thicknesses around the world. I knew just what to do with this sticky handful: give it to my artist friend Walt Zurko at The College of Wooster. He generously made the gorgeous cup-like object above and presented it to me this week.

Walt used every scrap of the clay, even recycling the shavings back into the exterior. There were tiny rock fragments in the original clay sample. They expanded differentially during the heating process and one made a small crack at the lip. I like it — it gives the piece character, like the crack in the Liberty Bell. Walt used several techniques to produce an extraordinary patina on the outside, much of which is not adequately conveyed in my amateur image.

Now we have in the geology department at Wooster a beautiful work of art made from the most famous clay in geological history. Aren’t the liberal arts wonderful?

Inside the tunnels at Geulhemmmerberg, The Netherlands, in August 2010. The rock forming the ceiling is Paleogene and most of the walls are made of Cretaceous limestone. The Cretaceous-Paleogene boundary is visible about a third of a meter down from the top of the wall in the background.

The complicated Cretaceous-Paleogene boundary at Geulhemmmerberg, The Netherlands. This gray clay is one of the thickest boundary clays in the world. I collected a chunk from this section for Walt’s artistic creation.

Wooster’s Fossils of the Week: Tiny little oysters (Lower Paleocene of Mississippi)

June 26th, 2011

This week’s fossils are by no means rare — last year Megan Innis and I picked up dozens of them at a muddy outcrop near Starkville, Mississippi, on our Cretaceous-Paleogene boundary expedition (click “Alabama” and “Mississippi” in the tags to the right for entries from that trip). They are, though, significant indicators of a particular kind of ecological system that appeared in the oceans of southeastern North America after the cataclysm of the Cretaceous Extinction.

The specimens pictured above are Pycnodonte pulaskiensis, a local species of oyster that belongs to a very prolific genus found around the world. Pycnodonte ranges from the Lower Cretaceous (about 140 million years ago) to, it appears, today. Kase and Hayami (1992) appear to have found this oyster — or a close relative — still living in submarine caves near Japan. This makes them a kind of “living fossil”, a group with a very long history of evolutionary stability.

This longevity fits into our Pycnodonte pulaskiensis story. These fossils are very common in the lowest Paleocene sediments just above the extinction horizon that marks the fiery end of the Cretaceous. After all that devastation (and Alabama was uncomfortably close to the impact site of Chicxulub), P. pulaskiensis appeared first to reoccupy the seafloor muds. They were virtually alone in this muddy habitat, and so lived there in great numbers. We call this kind of early successional species an “opportunist” (in the good sense!) taking advantage of a recently emptied niche.

Our little oysters in the Clayton Formation near Starkville, Mississippi.

Paul Taylor, Megan Innis and George Phillips at the Cretaceous-Paleogene boundary near Starkville, Mississippi in May 2010. Our oysters were found directly below Megan's feet.

These little oysters weren’t entirely alone, though. Many of them have small beveled holes in the center of their left valves, producing the ichnofossil Oichnus. These are apparently the traces of naticid gastropod predators (see Dietl, 2003) that drilled the holes to kill and eat the oyster soft parts.  (And who can blame them?) Several shells also have encrusting foraminiferans like Bullopora and Ramulina. Small hints of a recovering ecosystem setting the stage for the modern fauna we see in the northern Gulf of Mexico today.


Dietl, G.P., 2003. Traces of naticid predation on the gryphaeid oyster Pycnodonte dissimilaris: Epifaunal drilling of prey in the Paleocene. Historical Biology 16: 13-19.

Kase, T. and Hayami, I., 1992. Unique submarine cave mollusc fauna: composition, origin and adaptation. Journal of Molluscan Studies 58: 446-449.

The best Cretaceous-Paleogene boundary yet

August 10th, 2010

MAASTRICHT, THE NETHERLANDS–The Cretaceous-Tertiary boundary (K/T, or as I should be writing, the “Cretaceous-Paleogene” boundary, or K/Pg) has been one of the Wooster Geology themes this summer. We saw it in Alabama and Mississippi in May, and in Israel in June. The view of it here in The Netherlands, though, is far different. We explored it from below in the Maastrichtian tunnels at Geulhemmmerberg (N50.86692°, E5.78357°). This three-dimensional view, combined with the fact that this boundary section may be the most complete ever found, made today very special. We had a secular geological pilgrimage to the mysterious global events at the end of the Cretaceous.

After walking a long distance through the maze of tunnels guided by John Jagt of the Maastricht Natural History Museum and Rudi Dortangs, a very keen and accomplished amateur paleontologist (with a new mosasaur to his credit), we came upon excavations at the roof line which uncovered a thick sequence of clays and carbonate sand mixed together. The K/Pg boundary is a highly-irregular hardground surface with many Thalassinoides burrows penetrating up to two meters below. Carbonate sands are directly above the boundary, with the clay layers of varying vertical distances but rarely sitting on the hardground. There are at least seven clays, with the largest (Layer D) several centimeters thick. Since this boundary is near the roof of the tunnels, the bottom layers were often the ceiling above us so that we could see the very latest Cretaceous and earliest Paleogene exposed as a kind of upside-down bedding plane.

Two big surprises for: I knew there were multiple clay layers in some places, but to finally see them made them real for me. The traditional view since 1980 has been one clay layer representing the dust and debris from the meteorite impact settling back to Earth. Multiple clay layers makes this story much more complex, especially since some of the layers combine and split laterally. Maybe they were reworked during the storms of that “Global Winter”?

The second surprise was to learn that there were ammonites which definitely survived the extinction and lived briefly in the Paleogene. When these fossils were first found it was assumed they had been reworked from the Upper Cretaceous, but new studies show that they contain sediments which are indisputably Paleogene. Whether this is enough for us to change the textbooks is an interesting question: there are so few of the fossils, and in even fewer places. Nevertheless, some ammonites extend into the Paleogene.

Andrej Ernst and John Jagt at the boundary section in the Maastrichtian tunnels at Geulhemmmerberg.

This is a day I will always remember. For a historical geologist like me, it doesn’t get better!

A Great Unconformity

July 16th, 2010

I almost forgot our quick side trip at the end of the day. With the Green River Formation behind us (literally, in this photo), we turned to view a fantastic example of an angular unconformity here in central Utah. Although there are several significant unconformities in the area, this unconformity is probably my favorite, because it shows paleotopography as you follow it regionally from west to east.

The photo above shows the unconformity that places the Paleogene Colton Formation on top of the vertical Jurassic Twist Gulch Formation.

The photo above shows the unconformity that places the Paleogene Colton Formation on top of the vertical Jurassic Twist Gulch Formation.

Wooster geologist in New Zealand!

July 13th, 2010

CHRISTCHURCH, NEW ZEALAND–And it’s not me! Wooster geology student Andrew Collins is in a study abroad program on the South Island of New Zealand.  He has promised to share with us his geological experiences now and then. Andrew recently traveled to a town called Springfield near Christchurch and visited some amazing Paleogene limestone exposures on Castle Hill. This is an extreme example of karstic weathering.

Paleogene limestone on Castle Hill, South Island, New Zealand. Photograph by Andrew Collins.

Beautiful, eh? Andrew will share more New Zealand geology with us through this blog and his own.

This summer we’ve had Wooster geologists in Alaska, the southern USA, Ohio, Israel, Iceland and Utah … and we’re only halfway through our field season. Gotta love it!

Field Camp in Utah – A Woo Reunion

July 11th, 2010

Hello from Ephraim, Utah!! I just finished teaching my three week portion of Ohio State’s field camp with David Elliot (OSU, igneous petrology). To my surprise this year, field camp became a mini Wooster reunion, because Elyssa Krivicich (’09) was enrolled in field camp as a student. Elyssa moved on from Woo to OSU’s School of Earth Sciences, where she is focusing on paleontology under Bill Ausich, a colleague of Mark Wilson from their Estonia days (and a good friend of mine from my time at OSU).

Field camp this year has been just as great as usual. What possibly could be bad about spending each day in the Utah sun mapping? Yes, the days can be long and sometimes tiring (especially when you are grading), but the time mapping makes up for everything. Most of the mapping thus far was in Paleogene strata of the Sanpete Valley, but we did venture off for a camping trip to Marysvale, one of Utah’s volcanic provinces.

Because field camp is over, I can now turn my attention to field work with my I.S. students. Elizabeth Deering arrived in Utah on Saturday and is working with me here in Utah on the Green River Formation stromatolite lithofacies. I’m looking forward to days of fossil collecting in carbonates with Elizabeth. My other I.S. student, Jesse Davenport, is also here with us in Ephraim, assisting with field work. However, he will leave near the end of July to work in the Tobacco Root Mountain region of Montana on a Keck project. So, he’ll have to switch gears from Paleogene lacustrine strata to Archean metamorphics. Please stay tuned for more on our adventures in Utah, as we just completed our first day in the field!!

Elyssa Krivicich ('09) is hard at work during field camp, studying the packstone intervals in the Green River Formation on White Hill (Ephraim, Utah).

A paleontological meeting at the Owl Creek Formation

May 28th, 2010

RIPLEY, MISSISSIPPI — On our last full field day we met a team from the American Museum of Natural History (led by paleontologist Neil Landman) and converged on the famous Late Cretaceous Owl Creek Formation exposures near Ripley in northern Mississippi.  This site has been studied since 1810 and has produced extraordinary fossils, especially ammonites with pearly layers of aragonite still preserved in their shells.  As fun as the geology was, it was even more entertaining to see the mix of southern and New York accents and mannerisms on the outcrop!

The gray unit in the bottom half of the cliff is the Owl Creek Formation (Late Cretaceous); the brown and orange sands above are the Clayton Formation (Lower Tertiary). Yet another example of the K/T boundary on this trip.

A mix of geologists from England, Ohio, Michigan, Mississippi, Kansas and New York at the Owl Creek Formation section near Ripley, Mississippi.

Bryozoan Paradise at the K/T Boundary

May 27th, 2010

NEW ALBANY, MISSISSIPPI — One of the main advantages of being a geologist in a liberal arts program is the diversity of experiences our students and faculty have.  While some Wooster geologists are enjoying a “soft rock” adventure in the Cretaceous-Tertiary sediments in the Deep South, others are exploring “hard rock” quarries in the North.  Later this summer we may have simultaneous posts from Alaska, Iceland, Utah and Israel.

Today the southern expedition was very successful in its task to find bryozoans just below and just above the Cretaceous-Tertiary boundary.  Paul Taylor is a happy man.

Numerous bryozoans (the twig-like fossils) in the uppermost Cretaceous Prairie Bluff Formation east of New Albany, Union County, Mississippi.

The Cretaceous-Tertiary boundary east of New Albany, Union County, Mississippi. The uppermost Cretaceous is the brown clay, and the lowermost Tertiary is the orange sand at Megan's painted fingertip.

We meet the Cretaceous-Tertiary boundary in Mississippi

May 25th, 2010

STARKVILLE, MISSISSIPPI — George Phillips took us to a series of Starkville outcrops today straddling the Cretaceous-Tertiary boundary.  The boundary here is gradational and generally marked by a color change from gray in the upper Prairie Bluff Formation to light brown in the lower Clayton Formation.  Since we want to collect fossils just below and just above the boundary, these localities were ideal for us.

Megan Innis and George Phillips at the Cretaceous-Tertiary boundary in Starkville, Mississippi.

We were able to collect many encrusters and borings above and below this fateful event horizon.  I was most impressed by the diversity of encrusting foraminiferans on shells and phosphatic pebbles on both sides of the K/T, apparently showing little effects of the extinction.  A long time ago I did some systematic and paleoecological work with this group, so I may return to them to test these observations.

We also noted the proliferation of tiny oysters (especially Pycnodonte pulaskiensis) in the Clayton sediments immediately above the extinction horizon.  These are part of the initial survival and recovery fauna and thus keys to the future repopulation of this shallow marine ecosystem.

Small oysters in the lowermost Clayton Formation (Paleocene) in Starkville, Mississippi.

Mud, Sun and Fossils

May 22nd, 2010

GREENVILLE, ALABAMA — Reconnaissance is over for this part of the state, and our work commenced this morning.  We want to find good sclerobiont communities above and below the Cretaceous-Tertiary boundary, so here that means we want specimens from the Upper Cretaceous (Maastrichtian) Prairie Bluff Formation and the Paleocene (Danian) Clayton Formation.  That means plenty of muddy creekbeds and sun-smacked roadcuts.

Megan Innis (below) and Caroline Sogot (above) collecting bored and encrusted fossil oysters from the Prairie Bluff Formation in Mussel Creek (N 31.97259°, W 86.70387°).

Megan (in the fashionable yellow wellies) and Caroline collecting oysters from the Prairie Bluff Formation along Alabama 263 (N 32.04082°, W 86.79367°).

This would be a good time to mention that Caroline’s father is a famous magician in England with the stage name Jack Stephens.  We think this is very cool.  And I quickly add, Megan’s father Jeffrey is a famous pediatric geneticist at the University of Michigan.  We like that too!

This is the kind of fossil we like. It is a bivalve shell from the Clayton Formation (Tertiary, Danian) thoroughly bored by sponges. Unfortunately it is also well locked into this silicified rock matrix!

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