Team Columbia returns in high spirits with bountiful samples!

July 22nd, 2015

I.S. students, Kaitlin and Maddie enjoying the sunshine and representing Wooster below a fascinating ice tunnel.

I.S. students, Kaitlin and Maddie enjoying the sunshine and representing Wooster below a fascinating ice tunnel.

Guest Bloggers: Maddie Happ and Kaitlin Starr (Girdwood, Alaska)

Team Columbia is back from an exciting 8 days in the field.  Dr.Wiles, Nick Wiesenberg, Maddie Happ and Kaitlin Starr traveled via helicopter to Columbia Bay, Alaska beginning July 15th and returning July 21st. The first half of the trip was spent on the West Branch of Columbia Bay. Despite rainy days and blustery winds, we accomplished quite a bit of work! During our time on the West Branch, the team updated an old growth site, known as the Rock Tor, and collected samples from another living tree site near Kadin Lake. In addition to these living tree samples, the team collected cores and cross sections from newly exposed wood that were killed during the initial advance of Columbia Glacier.

    Kaitlin recording sample numbers and GPS locations at our first site.

Kaitlin recording sample numbers and GPS locations at our first site.

On July 18th, we were transferred across the bay to a location known as the Land Lobe. The team created base camp on the Great Nunatak side of the Land Lobe, as opposed to past years when groups were limited to the moraine due to the previous glacier terminus. Finally, the weather gods were on our side, and abundant sunshine allowed for productive days. We collected samples from the fans surrounding our base camp. On our last night in Columbia, we climbed to the tree line to update another living tree site titled the Son of the Great Nunatak. The alpine forest made for a wonderful last dinner in the Alaskan wilderness. On our final morning (with great weather still hanging on), Dr.Wiles and Nick recieved helicopter support to jump across the river to the other side of the Land lobe, where they collected newly exposed samples to complete a previously sampled site.


Team Columbia enjoying sunshine and exploring sites at our second camp near the Great Nunatak.

Team Columbia encountered a few minor setbacks throughout the trip, including gritty oatmeal, killer porcupines, and constant stumbling (particularly near waterfalls); however, it was a fabulous adventure overall! I.S. students, Maddie and Kaitlin are excited to return to the Wooster Tree Ring Lab and begin exploring the great stories behind these logs.

    Photo of the East Branch of Columbia Glacier captured from the helicopter.

Photo of the East Branch of Columbia Glacier captured from the helicopter.

Wooster’s Fossil of the Week: A coiled nautiloid from the Middle Devonian of Ohio

July 17th, 2015

Goldringia cyclops Columbus Ls Devonian 585The above fossil is a nautiloid cut in cross-section, showing the large body chamber at the bottom and behind it to the left and above the phragmocone, or chambered portion of the conch (shell). It is a species of Goldringia Flower, 1945, found in the Columbus Limestone (Middle Devonian, Eifelian) exposed in the Owen Stone Quarry near Delaware, Ohio. It is a nice specimen for both what it shows us about a kind of nautiloid coiling and for clues to its preservation.

This specimen was originally labelled Gyroceras cyclops Hall, 1861. In 1945, Rousseau Flower designated this taxon the type species of Goldringia. I can’t tell if we really have G. cyclops here or some other species, so I’m leaving it at the genus level. The old name lingers, though, in the term for this kind of open coiling: gyroceraconic. It is one of the earliest examples of the nautiloids having the phragmocone positioned above the body chamber, presumably for stable buoyancy.
Pentamerid embedded 071315I like the clues to the early history of this conch after death. The chambers are entirely filled with sediment, a fossiliferous micrite. You can see places where the original shell was broken and larger bits infiltrated, like the whole brachiopod shown above. This brachiopod appears from its cross-section to be a pentamerid. Also visible are strophomenid brachiopods and gastropods.
Winifred GoldringRousseau Hayner Flower (1913–1988) described Goldringia in 1945. He doesn’t directly say who he named it after, but he thanks “Dr. Winifred Goldring of the New York State Museum” in the acknowledgments. We can tell Flower’s story later (and it’s a good one), but this gives us a chance to introduce Winifred Goldring (1888-1971). She was the first paleontologist to describe the famous Gilboa fossil flora (Devonian) in upstate New York, and she was the first woman State Paleontologist of New York (or anywhere, for that matter). (Now there is Lisa Amati in this prestigious position. Congratulations, Lisa!) Goldring grew up near Albany, New York, one of nine children in a very botanical family. She graduated from Wellesley College in 1909 with a bachelor’s degree in geology (very unusual for a woman at the time). She stayed at Wellesley to earn a master’s degree (1912). She also taught geology courses at Wellesley. In 1913 she studied geology at Columbia University with the famous Amadeus Grabau. In 1914, Goldring joined the scientific staff at the New York State Museum as a “scientific expert”. She worked her way up through the many ranks there to become State Paleontologist in 1939. She is best known as a paleontologist for her work with the fascinating Gilboa fossil forest, bringing her early upbringing by botanists to full circle. Along the way she was the first woman president of the Paleontological Society (in 1949) and vice-president of the Geological Society of America (in 1950). A hero of paleontology.


Flower, R.H. 1945. Classification of Devonian nautiloids. American Midland Naturalist 33: 675–724.

Goldring, W. 1927. The oldest known petrified forest. Scientific Monthly 24: 514–529.

Koninck, L.G.D. 1880. Faune du Calcaire Carbonifere de la Belgique, deuxieme partie, Genres Gyroceras, Cyrtoceras, Gomphoceras, Orthoceras, Subclymenia et Goniatites. Annales du Musee Royal d‘Histoire Naturelle, Belgique 5: 1–333.

Wooster’s Fossil of the Week: A small lobster from the Lower Cretaceous of North Yorkshire, England

July 10th, 2015

Meyeria ornata fullMae Kemsley (’16) found this little beauty during her Independent Study fieldwork last month on the Speeton Cliffs of North Yorkshire. It is Meyeria ornata (Phillips, 1829), a decapod of the lobster variety, from the Speeton Clay. It is relatively common in Bed C4, so much so that it is referred to as “the shrimp bed”. Mae is the only one of our team of four who found one, though, so it is special to us. The above is a lateral view, with the head to the left and abdomen on the top of this small concretion.
Dorsal Meyeria ornataHere is a dorsal view looking down on the abdominal segments.
Screen Shot 2015-07-01 at 9.14.03 PMSimpson and Middleton (1985, fig. 1b) have this excellent diagram of Meyeria ornata in life position. The scale bar is one centimeter. “Details of pleopods, third maxillipeds and first antennae of M. ornata unknown. Dashed line represents length of extended abdomen. Symbols: a branchiocardiac groove; c postcervical groove; e cervical groove; m3 third maxilliped; p pereiopod; pi pleopod; t telson; u uropods; x ‘x’ area; r rostrum; al first antennae; a2 second antennae; ar antennal ridge; sr suborbital ridge; 1,2,3. branchial ridges.”

According to Simpson and Middleton (1985), Meyeria ornata actively crawled about on the muddy substrate like modern lobsters. They did not have true chelae (large claws), so they were likely scavengers in the top layers of the sediment rather than predators.

3 Mae working 060915Mae at work.


Charbonnier, S., Audo, D., Barriel, V., Garassino, A., Schweigert, G. and Simpson, M. 2015. Phylogeny of fossil and extant glypheid and litogastrid lobsters (Crustacea, Decapoda) as revealed by morphological characters. Cladistics 31: 231-249.

M’Coy F. 1849. On the classification of some British fossil Crustacea with notices of new forms in the University Collection at Cambridge. Annals and Magazine of Natural History, series 2, 4, 161-179.

Phillips, J. 1829. Illustrations of the geology of Yorkshire, Part 1. The Yorkshire coast: John Murray, London, 184 p.

Simpson, M.I. and Middleton, R. 1985. Gross morphology and the mode of life of two species of lobster from the Lower Cretaceous of England: Meyeria ornata (Phillips) and Meyerella magna (M’Coy). Transactions of the Royal Society of Edinburgh: Earth Sciences 76: 203-215.

Classifying the unknown: the lunar edition

July 7th, 2015

New York, NY – [Guest Blogger Annette Hilton]

This summer I have the privilege of working and living in New York City at the American Museum of Natural History. I, along with several other students, have the opportunity to work with the museum’s researchers through an REU (Research Experience for Undergraduates) program funded by the National Science Foundation.

Front entrance of the American Museum of Natural History (AMNH).

Front entrance of the American Museum of Natural History (AMNH).

Entrance to the Earth and Planetary Sciences Department, AMNH.

Entrance to the Earth and Planetary Sciences Department, AMNH.

As a geologist, I am working in the Earth and Planetary Sciences Department. I am under the mentorship of Dr. Juliane Gross, a research associate at the museum. Together we have been working with a small sample from an unnamed lunar meteorite found in Northwest Africa. Our goal for the end of the summer is to classify and name this mysterious lunar meteorite.

Photo from:

Photo from:

Meteorites are undoubtedly cool, but why should we care so much about the Moon? According to the Giant Impact Hypothesis, around 4.5 Ga proto Earth collided with another planetary body called Theia. Though an extremely violent impact, Earth quickly reformed and the remaining debris circled our planet, eventually forming the Moon. This theory is generally accepted but still under reform. We know that the Moon and Earth are extremely similar in composition, making their dual formation likely.

What the formation of Earth and the Moon may have looked like.  Photo from:

What the formation of Earth and the Moon may have looked like.
Photo from:

Because the Moon and Earth are so similar, we can study the Moon to gain information about our early solar system and early Earth. If we want to know more about how Earth formed, how old it is, and what the proto-material was like, we can turn to our closest neighbor in the solar system. Because the Moon is no longer geologically active, it has preserved information from the span of over 4.0 Ga. This is a sharp contrast to Earth, whose original material has all since been recycled.

Before the Apollo and Luna missions, lunar information was all theory. We had no data to put lunar theories into context and were unable to classify lunar meteorites because we had nothing to compare them to. From all of the Apollo missions, only ~382 kg of lunar rocks and soils were brought back. Because of logistical reasons, all of the lunar missions landed and collected samples in the same relatively small area: the lunar mare.

Mapped image of the Moon with Apollo and Luna missions landing sites.  Photo from:

Mapped image of the Moon with Apollo and Luna missions landing sites.
Photo from:

Later, data collected by satellites would show this area to be a chemical anomaly in comparison to the rest of the Moon. The lunar mare largely contains higher levels of elements including rare earth elements (REEs) in comparison to the rest of the Moon.

Elemental map of the Moon showing high levels of Thorium in areas of Apollo and Luna landings.  Photo from:

Elemental map of the Moon showing high levels of Thorium in areas of Apollo and Luna landings.
Photo from:

So now we know that the samples collected from the Moon aren’t representative of its entire body. Much of what we consider to know and understand about the Moon today were based on Apollo, Luna samples and information. Because these samples aren’t representative, it is necessary to take a critical look at our current understanding of the Moon. Until we return, our only source of lunar rocks that come from places other than where the Apollo/Luna samples were collected are meteorites. So if we want to gain a clearer understanding of what the Moon is really like, we must study them.
You may be wondering how lunar meteorites arrive on Earth in the first place. Lunar meteorites come from the ejecta during an impact event on the Moon. When a meteoroid or other asteroidal body hits the Moon’s surface, lunar crust is displaced and gets ejected into space, eventually becoming trapped in Earth’s gravity field, allowing it to come to our surface.

Diagram of a meteoroid impact. Photo from:

Diagram of a meteoroid impact.
Photo from:

Meteorites are usually collected in deserts, like the Sahara or Antarctica, because they are easily located and preserved well in these areas. Teams of scientists search for meteorites each year in key locations and may at best return with some hundreds of samples.

Among those, only a small fraction may be lunar. On the whole, lunar meteorites are very rare–there have only been a total of 110 total unpaired lunar meteorites ever found.

Image of meteorite, exhibiting fusion crust, in Antarctica.  Photo from:

Image of meteorite, exhibiting fusion crust, in Antarctica.
Photo from:

Even though samples are limited, each new lunar meteorite gives us another chance to learn more about the Moon and expand our understanding of it.

In order to learn about our meteorite, my advisor and I have been studying our sample through chemical analysis and elemental x-ray mapping, which is done with an Electron Probe Micro-Analysis (EPMA). The machine can be programed to map the element distribution of the entire sample or just specific areas, but depending on the size of the area to be mapped the analysis can take several days. By analyzing single minerals within the sample we can get mineral chemistry in oxide weight percent, which has helped us to understand the mineralogy and petrography of our sample.

Annette Hilton (‘17) programing analysis of the unknown lunar meteorite in the EPMA, located in the Earth and Planetary Sciences Department at AMNH.

Annette Hilton (‘17) programing analysis of the unknown lunar meteorite in the EPMA, located in the Earth and Planetary Sciences Department at AMNH.

Soon we will be conducting LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry) on the sample to get data on trace and REEs that might be in our meteorite but are too minute for the EPMA to detect. This finer analysis will allow us to compare our sample more comprehensively to other lunar samples, and perhaps even hypothesize crystallization history. Currently we are working to calculate the bulk composition of our sample, which would enable us to use whole rock analysis as another comparative tool. Looking forward, we also hope to use the presence of different pyroxenes in the sample to calculate crystallization temperature, which could help us further understand our sample’s formation history.

By the end of the summer at AMNH we hope to submit a classification for the meteorite and work to publish about the sample. I am incredibly grateful for this exciting and valuable opportunity to learn and contribute towards lunar work.

SEM (Scanning Electron Microscope) image of our unknown lunar sample. Shown above is a terrestrial alteration crack, several melt veins (from shock impact), and plagioclase grains outlined by a matrix of olivine and pyroxene grains.

SEM (Scanning Electron Microscope) image of our unknown lunar sample. Shown above is a terrestrial alteration crack, several melt veins (from shock impact), and plagioclase grains outlined by a matrix of olivine and pyroxene grains.

Thank you to AMNH, NSF REU Program for Physical Sciences, Dr. Juliane Gross, and of course our wonderful professors at Wooster (particularly Dr. Meagen Pollock, professor of Mineralogy and Petrology).



Gross, J., Treiman, A.H., and Mercer, C.N., 2014, Lunar feldspathic meteorites: constraints on the geology of the lunar highlands, and the origin of the lunar crust: Earth and Planetary Science Letters, v. 388, p. 318–328.

Joy, K.H., and Arai, T., 2013, Lunar meteorites: new insights into the geological history of the Moon: Astronomy & Geophysics, v. 54, p. 4–28.

Korotev, R.L., 2005, Lunar geochemistry as told by lunar meteorites: Chemie der Erde-Geochemistry, v. 65, p. 297–346.

Taylor, S.R., Taylor, G.J., and Taylor, L.A., 2006, The moon: a Taylor perspective: Geochimica et Cosmochimica Acta, v. 70, p. 5904–5918.

Treiman, A.H., Maloy, A.K., Shearer, C.K., and Gross, J., 2010, Magnesian anorthositic granulites in lunar meteorites Allan Hills A81005 and Dhofar 309: Geochemistry and global significance: Meteoritics & Planetary Science, v. 45, p. 163–180.

Inspiring young female scientists through B-WISER

July 6th, 2015

Wooster, OH – [Guest bloggers Chloe Wallace and Mary Reinthal]

When thinking about geology, people tend to think first about rocks. We do love our rocks, preferably pillow basalts, but when Wooster’s campus hosted hundreds of young women science enthusiasts, we wanted to teach them a practical field skill: pace and bearing. Buckeye Women In Science, Education, and Research, or B-WISER got the chance to learn and apply an important skill for geologists. This type of outreach is important because it reminds students that science is fun.

B-WISER girls focus intently on measuring distances on the academic quad with their paces.

B-WISER girls focus intently on measuring distances on the academic quad with their paces.

For five days, girls ranging in ages from 14-16 were engaged in different fields of science hosted by departments around campus. The geology department was fortunate to have over thirty girls participate in a variety of super-awesome orienteering activities for two days. Each of the girls was supplied with packets outlining the daily activity and a compass to help them orient themselves. Even poor weather could not damper spirits, and inside activities were met with laughter and good energy.

By the end of the workshop, the budding geologists were able to make (and follow) their own scavenger hunt maps!

By the end of the workshop, the budding geologists were able to make (and follow) their own scavenger hunt maps!


Mary records bearing data from two young women geologists.

Mary records bearing data from two young women geologists.


On the first day, students were taught how to take a compass bearing and orient themselves to pinpoint a location. They learned their pace and how to use it to calculate distance. Professor of all things geology, Dr. Meagen Pollock, along with her summer research students Chloe Wallace, Julia Franceschi, and Mary Reinthal, guided activities and often participated alongside the students.

Wooster’s Fossils of the Week: An Upper Ordovician cave-dwelling bryozoan fauna and its exposed equivalents

July 3rd, 2015

1 Downwards 063015This week’s fossils were the subject of a presentation at the 2015 Larwood Symposium of the International Bryozoology Association in Thurso, Scotland, last month. Caroline Buttler, Head of Palaeontology at the National Museum Wales, Cardiff, brilliantly gave our talk describing cryptic-and-exposed trepostome bryozoans and their friends in an Upper Ordovician assemblage I found years ago in northern Kentucky. They were the subject of an earlier Fossil of the Week post, but Caroline did so much fine work with new thin sections and ideas that they deserve another shot at glory. We are now working on a paper about these bryozoans and their borings. Below you will find the abstract of the talk and a few key slides to tell the story.


Trepostome bryozoans have been found as part of an ancient cave fauna in rocks of the Upper Ordovician (Caradoc) Corryville Formation exposed near Washington, Mason County, Kentucky.

Bryozoans are recognized as growing from the ceiling of the cave and also from an exposed hardground surface above the cave. Multiple colonies are found overgrowing one another and the majority are identified as Stigmatella personata. Differences between those growing upwards and those growing down from the roof have been detected in the limited samples.

The colonies have been extensively bored, these borings are straight and cylindrical. They are identified as Trypanites and two types are recognised. A smaller variety is confined within one colony overgrowth and infilled with micrite. In thin section it is observed that the borings follow the lines of autozooecial walls and do not cut across. This creates a polygonal sided boring, suggesting that the colonies were not filled with calcite at the time of the boring. The second variety has a larger tube size and its infilling sediment has numerous dolomite rhombs and some larger fossil fragments including cryptostomes, shell and echinoderm pieces. These cut through several layers of overgrowing bryozoans. Some of the borings contain cylindrical tubes of calcite similar to the ‘ghosts’ of organic material described by Wyse Jackson & Key (2007).

Very localised changes in direction of colony growth due to an environmental effect are seen.

Bioclaustration in these samples provides evidence for fouling of the colony surface, indicating that the bryozoans overgrew unknown soft-bodied organisms.


Wyse Jackson, P. N., and M. M. Key, Jr. (2007). Borings in trepostome bryozoans from the Ordovician of Estonia: two ichnogenera produced by a single maker, a case of host morphology control. Lethaia. 40: 237-252.

2 Title 0630153 Location 0630154 Strat position 0630155 hdgd up 0630156 hdgd down 0630157 Growth up 0630158 Growth down 0630159 Stigmatella 06301510 Cartoon 06301511 Boring A 06301512 Boring B 06301513 Ghosts explanation14 Ghosts 06301515 Overgrowths 06301516 Further questions 063015

Link to posts from Wooster Geologists in the United Kingdom in June 2015

June 29th, 2015

11 Mae Meredith Filey BriggI spent 25 days in England, Scotland and Wales this month, 12 of them with these two happy Senior Independent Study students, Mae Kemsley (’16) and Meredith Mann (’16) — dubbed “Team Yorkshire”. We had to delay our blog posts until today. You can see all of them by clicking the UK2015 tag. It was a spectacular expedition. Thanks again to Paul Taylor, Jen Loxton, Joanne Porter, Tim Palmer, Patrice Reeder and Suzanne Easterling for the parts they played in this adventure. Thank you as well to Mae and Meredith who were not only sharp field paleontologists, they were great companions as well. They are shown above on the tip of Filey Brigg in North Yorkshire. (N54.21560°, W00.25842°; Google Earth image below. Cool study site!)

Screen Shot 2015-06-29 at 11.47.54 AM

Shikotan Island Tree Ring Chronology

June 26th, 2015

Guest blogger: Xiangyu Li

As one of the most militarized islands, because of the dispute between Japan and Russia (the Kuril Islands dispute), Shikotan Island has remained a mystery to the world of tree rings and climate studies until now.

1447443_original Figure 1. Deserted Russian tank on Shikotan island (from

Shikotan Island directly on the margin between the Pacific and Eurasian Plates. This special location indicates that this island is greatly influenced by geological factors, such as tsunami, earthquake, and large changes in climate (see photos below).


Figure 2. Big crack after the Shikotan Island earthquake of 1994.

see ice

Figure 3. Shikotan Island surrounded by sea ice (Wikipedia).

In order to better define the climate history of the Island in 2014 Russian geologist E. Dolgova and M. Alexandrin collected core samples from larch, spruce and fir trees on Shikotan islands.


Figure 4. Location of  collection sites of all Shikotan cores. The island is approximately 30 km long (image from GooglEarth).

The purpose of this research is to find the climate information from these cores. These cores are properly sanded and marked. Forty six cores were collected from Shikotan Island and 20 were used to construct the chronology for this island.


Figure 5. Family picture of all cores in the chronology

As we can see, some cores are less than 100 years old and some cores can be dated back to 18th century. Despite the age difference these 20 cores correlate with each other well.The purpose of this research is to extract climate information from these cores. These cores are properly sanded and marked by year. Forty six cores were collected from Shikotan Island and 20 were used to construct the chronology for this island.

standardized tree ring indices

The tree ring width can be influenced by various factors other than climate signal, such as the growth trends and natural competition. The growth trends is the major factor that we want to eliminate. The above picture shows us the standardized tree ring measurements by removing the growth trends. The blue line is the sample size. This is the first tree-ring record from Shikotan Island.

Final copy

The standardized ring width chronology has a slight downward trend since 1900. I compared the standardized tree ring data with the meteorological data from Nemuro station (130 years long). It appears that September temperature has a strong negative correlation with the tree ring width. The correlation is 0.43, which is far above the 99% confidence level. The reason for such negative correlation is unknown, however, it may be related to changes in sea ice extent.

In addition to examining the correlation between ring width and temperature, I focused on the possible relationship between tree ring width and natural hazards, such as tsunami and earthquake.

After looking at the tsunami occurrence data from NOAA, I found that sometimes tsunami corresponded with a year of rapid growth. For example, in 1963, there are two tsunamis on Shikotan Island and some cores has a bigger growth this year compared to the year before. Photos below are two cores that show the correlation with the tsunami record and there are more cores have a correlation with the tsunami record. This relationship is under investigation.


Figure 6. Core K02E5B


Figure 7 K02E7B

Last day of fieldwork in England: A working quarry and another great unconformity

June 26th, 2015

1 Doulting quarry sawBRISTOL, ENGLAND (June 26, 2015) — Tim Palmer has a professional interest in building stones, and a passion for sorting out their characteristics and historical uses. He thus has many contacts in the stone industry, from architects to quarry managers. This morning we visited the Doulting Stone Quarry on the outskirts of Doulting near Shepton Mallet in Somerset. Here a distinctive facies of the Jurassic Inferior Oolite is excavated for a variety of purposes. The rock has a lovely color, is relatively easy to work, and is durable. Above is a quarry saw that cuts out huge blocks from the natural exposure.

2 Thalassinoides layer DoultingSuch sawing produces great cross-sections for geologists to examine. We were particularly interested in that light-colored unit above with the irregular top and dark sediment-filled holes. The holes are part of a network of Thalassinoides burrows (tunnels made by Jurassic crustaceans) and reduce the value of the rock as a building stone. There is thus lots of it laying around the quarry yard for study.

3 Pinnid likely Trichites cross section DoultingOne impressive fossil exposed by the sawing is this pinnid bivalve, probably Trichites.

4 Burrow fill sediments DoultingThe Thalassinoides burrows are filled with a poorly-cemented sediment. It is full of little fossils, so we collected a bag of it for microscopic examination. It may give us clues as to what communities lived on the surface of this burrowed unit when it was part of the Jurassic seafloor.

5 shaping saw DoultingWe had a tour of the quarry shops, which included seeing these giant rock saws in action. Many of the saws are controlled by computers, so elaborate cuts can be made.

6 Medieval stone breaking marksThis rock has been quarried since Roman times, so there is over 2000 years of stone working here. The quarry owner set aside this rock face which shows chisel marks made in Medieval times. Wooden wedges were jammed into chiseled channels and then pulled over days to eventually crack the stone free.

7 Tedbury Camp wavecut surface along strikeAfter the quarry visit, Tim Palmer and I tromped through the woods and eventually found (with the help of several locals) an exposure known as Tedbury Camp. It is another Jurassic-on-Carboniferous unconformity like we saw at Ogmore-By-Sea earlier in the week. A century ago quarry workers cleared off this surface of Carboniferous limestone. It is a wave-cut platform on which Jurassic sediments (the Inferior Oolite) were deposited. The surface has many geological delights, including faults, drag folds, differentially-weathered cherts and carbonates, and Jurassic borings and encrusters. Beautiful.

8 wavecut surface foldingIn this view of the surface you may be able to see the odd folding of the dark chert layers in the right middle of the image. These seem to be drag folds along a fault. They clearly predate the Jurassic erosion of the limestone surface. The overlying Jurassic can be seen in the small outcrop on the left near Tim.

9 section view of wavecut surfaceIn this cross-section of the erosional surface you can clearly see we’re working with an angular unconformity.

10 filled borings wavecutTrypanites borings are abundant across this surface, most filled with lighter Jurassic sediment. There are other borings here too that deviate from the straight, cylindrical nature of Trypanites.

11 curved borings wavecutI don’t know yet how to classify these curved borings. They resemble Palaeosabella.

12 Encrusting bivalve wavecutHere is a Jurassic bivalve attached to the Carboniferous limestone at the unconformity. Most of the encrusters have been eroded away.

13 Tim on wavecut platformThere are many possibilities for further study of the Tedbury Camp unconformity. This was a productive site for our last field visit in England this year. Thank you very much to Tim Palmer, seated above, for his expertise, great companionship, and generosity with his time. It was a reminder of how much fun we had together in the field twenty years ago.

My month of geology in the United Kingdom has now come to an end. My next two days will be devoted to packing up and making the long train and then plane flights home. What a wonderful time I had, as did my students on the earlier part of the trip, Mae Kemsley and Meredith Mann. Thank you again to Paul Taylor for his work with us in Scarborough. I am very fortunate with my fine British friends.

For the record, the important locality coordinates from this trip —

GPS 089: Millepore Bed blocks N54.33877°, W00.42339°

GPS 090: Spindle Thorn Member, Hundale Point N54.16167°, W00.23326°

GPS 091: Robin Hood’s Bay N54.41782°, W00.52501°

GPS 092: Northern limit of Speeton Clay N54.16654°, W00.24567°

GPS 093: Northern limit of Red Chalk N54.15887°, W00.22261°

GPS 094: South section Filey Brigg N54.21674°, W00.26922°

GPS 095: North section Filey Brigg N54.21823°, W00.26904°

GPS 096: Filey Brigg N54.21560°, W00.25842°

GPS 097: D6 of Speeton Clay N54.16635°, W00.24520°

GPS 098: C Beds of Speeton Clay N54.16518°, W00.24226°

GPS 099: Lower B Beds of Speeton Clay N54.16167°, W0023326°

GPS 100: Possible A Beds of Speeton Clay N54.16129°, W00.23207°

GPS 101: A/B Beds of Speeton Clay N54.16035°, W00.22910°

GPS 102: C7E layer of Speeton Clay N54.16447°, W00.24043°

GPS 103: Lavernock Point N51.40589°, W03.16947°

GPS 104: Triassic deposits, Ogmore-By-Sea N51.46543°, W03.64094°

GPS 105: Sutton Stone Unconformity N51.45480°, W03.62609°

GPS 106: Sample of lowermost Sutton Stone N51.45455°, W03.62545°

GPS 107: Nash Point N51.40311°, W03.56212°

GPS 108; Devil’s Chimney N51.86402°, W02.07905°

GPS 109: Fiddler’s Elbow N51.82584°, W02.16541°

GPS 110: Doulting Stone Quarry N51.18993°, W02.50245°

GPS 111: Tedbury Camp unconformity N51.23912°, W02.36515°


Wooster’s Fossils of the Week: An encrusted bivalve external mold from the Upper Ordovician of Indiana

June 26th, 2015

1 Anomalodonta gigantea Waynesville Franklin Co IN 585I love this kind of fossil, which explains why you’ve seen so many examples on this blog. We are looking at an encrusted external mold of the bivalve Anomalodonta gigantea found in the Waynesville Formation exposed in Franklin County, Indiana. I collected it many years ago as part of an ongoing study of this kind of preservation and encrustation.
2 Anomalodonta gigantea Waynesville Franklin Co IN 585 annotatedTo tell this story, I’ve lettered the primary interest areas on image above. First, an external mold is an impression of the exterior of an organism. In this case we have a triangular clam with radiating ribs in its shell. The exterior of the shell with its ribs was buried in sediment and the shell dissolved, leaving the basic impression above. It is a negative relief. Please now refer to the letters for the close-up images below.

3 Bryo Anomalodonta gigantea Waynesville Franklin Co INA. At the distal end of the bivalve mold is what looks at first to be the original shell. It is calcitic, though, and we know this bivalve had an aragonitic shell. A closer look shows that this is actually the attaching surface of an encrusting bryozoan that bioimmured the original bivalve shell, which has since dissolved away. This smooth surface is the bryozoan underside; we see the characteristic zooecia (tubes holding the individual zooids) only when this surface is weathered away.

4 Borings Anomalodonta gigantea Waynesville Franklin Co INB. These tubular objects are infillings of borings (maybe Trypanites)that were cut into the original aragonitic shell of the bivalve. The tunnels of the borings were filled with fine sediment, and then the shell dissolved away, leaving these casts of the borings.

5 Inarticulate scar Anomalodonta gigantea Waynesville Franklin Co INC and D. In the middle of the external mold is this curious circular feature (C) mostly surrounded by a bryozoan (D). There was at one time a circular encruster, likely an inarticulate brachiopod like Petrocrania, that sat directly on the external mold surface. The bryozoan colony grew around but not over it because it was alive and still opening and closing its valves for feeding. The bryozoan built a vertical sheet of skeleton around it as a kind of sanitary wall. You may be able to see the other three or four structures in the top image showing brachiopod encrusters that left the building. This is an example of fossils showing us a living relationship, even if one is not longer preserved.

This fossil and its sclerobionts (hard substrate dwellers) show us that soon after the bivalve died its aragonitic shell dissolved away, leaving as evidence the external mold in the sediment, the bioimmuring bryozoan, and the boring casts. Very soon thereafter bryozoans and brachiopods encrusted the available hard substrate. This is a typical example of early aragonite dissolution on the sea floor during a Calcite Sea interval.


Palmer, T.J. and Wilson, M.A. 2004. Calcite precipitation and dissolution of biogenic aragonite in shallow Ordovician calcite seas. Lethaia 37: 417-427.

Taylor, P.D. 1990. Preservation of soft-bodied and other organisms by bioimmuration—a review. Palaeontology 33: 1-17.

Taylor, P.D. and Wilson, M.A. 2003. Palaeoecology and evolution of marine hard substrate communities. Earth-Science Reviews 62: 1-103.

Wilson, M.A., Palmer, T.J. and Taylor, P.D. 1994. Earliest preservation of soft-bodied fossils by epibiont bioimmuration: Upper Ordovician of Kentucky. Lethaia 27: 269-270.

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