Archive for May, 2017

An evening with Hutton, Lyell, and Darwin at the Davison Rare Book Room

May 22nd, 2017

Middletown, CT – The Wooster Geologists at the Keck Consortium were treated to a visit to the Davison Rare Book Room. The Special Collections Librarian set out an impressive array of historical texts with geological significance. We were even permitted to touch the books and turn the pages! Thank you to the Wesleyan Special Collections and Archives for sharing these treasures and allowing us to look through them and take photos.

The 1690 book “Geologia: or, a Discourse Concerning the Earth Before the Deluge” by Erasmus Warren represents an early use of the word ‘geology’ to describe the study of Earth. Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

Scottish Geologist James Hutton is considered the father of modern geology. In his 1795 two-volume work, “Theory of the Earth,” he argues that Earth is very old and Earth’s features are shaped by natural processes that have occurred over long time scales. Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

In the 1800s, Charles Lyell expanded on and popularized Hutton’s ideas. Lyell argued that Earth evolves through small changes that operate continuously over geologic time, a concept known as “uniformitarianism.” Uniformitarianism opposed the prevailing view of catastrophism, in which Earth evolved through a series of catastrophic events. Today, we understand that natural processes have changed the Earth gradually over long time scales, that natural processes can change the rate at which they operate, and that Earth’s history includes occasional catastrophic events. Lyell’s 1839 “Elements of Geology” is a textbook for early geology students. Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

This diagram at the front of Lyell’s “Elements of Geology” (1839) shows the relationship between the “four great classes of rocks: aqueous, volcanic, metamorphic, and plutonic.” Today, we combine volcanic and plutonic into the singular igneous category and aqueous rocks are classified as sedimentary. Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

Of course, my favorite illustration in the Lyell 1839 text is columnar jointed basalt. Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

Lyell’s concept of “uniformitarianism” strongly influenced Darwin, who read Lyell’s work aboard the Beagle. This is a first-edition of Charles Darwin’s famous 1859 work “On the Origin of Species by Means of Natural Selection.” Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

Darwin’s book contains personal inscription from the author to his German tutor. Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

This “tree of life” figure in Darwin’s “On the Origin of Species” (1859) is the only illustration in the entire text! Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

Although Darwin used figures sparingly, paleontologists have long been using images in their publications. This 1854 “Remarks on some Fossil Impressions in the Sandstone Rocks of Connecticut River” by John C. Warren is credited as the first book to use photographs as scientific illustrations. Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

The front cover of Warren’s 1854 book contains a salt print of dinosaur tracks. Salt prints were made by soaking the paper in a salt solution then coating one side with silver nitrate. This created light-sensitive paper that darkened in places exposed to light, producing images. Photo credit: Courtesy of Wesleyan University, Special Collections & Archives.

Extracting a single element from a rock

May 20th, 2017

Chapel Hill, NC – As you know, Ben Kumpf (’18) and I are working in the Isotope Geochemistry lab at UNC Chapel Hill. We are measuring isotopes of strontium (Sr), lead (Pb) and neodymium (Nd) in basaltic pillow lavas from northern British Columbia. In order to measure the elements, we need to isolate them from the rest of the elements that make up our rocks. We purify individual elements using the method of column chemistry. A column is like a filter for elements; we pass our sample through the column and the column captures the element of interest, then we release and collect the element off the column to be analyzed later.

The first step to preparing our samples is to dissolve our rock powders in an acid solution. Ben Kumpf (’18) weighs small amounts of rock powder into Teflon vials. We add a series of acids to the vials and let them sit on a hotplate for a day or two until the powders are completely dissolved.

Once the samples are dissolved, we measure out a small amount of the solution into a new vial to run it through the column chemistry process. The first step to make a column “load” solution is to dry the sample solution down to a powder on a hotplate.

To the dried-down powder, we add an acid that is appropriate for the column that we’re using. For Sr, we’re adding nitric acid to the vials.

Now we’re ready to set up the columns. Dr. Ryan Mills (psychedelic lab coat) is showing Ben Kumpf (’18) how to add the resin.

This is what a column looks like up close. It’s suspended above a waste beaker. The white material that is filling the tube and neck is the resin. You can see it still settling out of solution. The resin that we use to isolate Sr was developed in response to the Chernobyl accident when it became necessary to remove radioactive Sr from milk (Vajda and Kim, 2010).

The chemical column process involves adding a series of solutions to the columns in a sequence that cleans the resin, conditions the resin for the sample load solution, introduces the sample, and rinses the sample through the resin. There’s a lot of pipetting and waiting for the solutions to move through the column during this stage.

Samples are centrifuged prior to loading. The centrifuge separates any undissolved solids from the liquid so that we only add the liquid portion to the column.

These columns are loaded with our Pb solutions.

Now that our sample has passed through the column, we release all of the Sr or Pb off of the column and collect it in our sample vial.

The last step in the process is to dry down the sample one final time. This makes a tiny bead at the bottom our vial. We will load this bead into a mass spectrometer to measure the isotope composition.

Now you can see why we need do our sample preparation in a clean lab.

References

Vajda, N. and Kim, C.-K. 2010. Determination of radiostrontium isotopes: A review of analytical methodology. Applied Radiation and Isotopes 68: 2306-2326.

Wooster’s Fossils of the Week: A bouquet of barnacles on a pectenid bivalve from the Upper Miocene of Virginia

May 19th, 2017

These beautiful fossils were found in York State Park by Mae Kemsley (’16). It was a surprise gift I found on my doorstep! They are fossil barnacles completely covering the exterior of a valve of the pectenid bivalve Chesapecten middlesexensis (Mansfield, 1936) from the Upper Pliocene. An excellent example of an ancient sclerobiont community.
This is the reverse of the specimen, showing the interior of the host shell. Note the large single muscle scar typical of monomyarian pectenid bivalves.
Chesapecten is well known among paleontologists. The genus preserves a distinct evolutionary sequence, as seen in the above famous figure from Ward and Blackwelder (1975). This image has been reproduced in countless articles and textbooks.
Chesapecten was also the first fossil from North America to be illustrated in a scientific publication. The above image of what we now know as Chesapecten jeffersonius was illustrated in the third volume of Martin Lister’s Historiae Conchyliorum in 1687.
Martin Lister FRS (1639 – 1712) was a natural historian and physician born into a prominent family in Radcliffe, England. His father, Sir Martin Lister, was a member of the Long Parliament in the eventful politics of mid-17th century England. He was a nephew of James Temple, a regicide (or patriot, take your choice) and Sir Matthew Lister, physician to Charles I (victim of said regicide). These were just a few of his family connections to politics and science.

Martin Lister was graduated from St John’s College, Cambridge, in 1659, and a year later elected a fellow there. He served as a physician for many years in York, including three years as Queen Anne’s doctor. He became a Fellow of the Royal Society in 1671. He died in Epsom in 1712.

Martin Lister was an extraordinary naturalist, becoming the first conchologist (one who studies shells) and arachnologist (a spider expert). He was a prolific writer, so we know much about what he did, how he worked, and his motivations. He discovered ballooning spiders and invented the ubiquitous histogram. For us his most significant work was Historiae Conchyliorum (1685-1692), which had 1062 plates engraved by his daughters, Anna and Susanna. In keeping with his times, Lister noted the resemblances between fossil and modern shells, but believed the fossils were rocky replicas, not actual remnants of living organisms. He would no doubt be thrilled with our modern views of fossils and evolution.

References:

Kelley, P.H. 1983. The role of within-species differentiation in macroevolution of Chesapeake Group bivalves. Paleobiology 9: 261-268.

Lister, M. 1687. Historiae Conchyliorum, volume III. Londini, aere incisi, sumptibus authoris.

Ward, L.W. and Blackwelder, B.W. 1975. Chesapecten, a new genus of Pectinidae (Mollusca, Bivalvia) from the Miocene and Pliocene of eastern North America: USGS Professional Paper 861. US Government Printing Office.

Wooster Geologists graduate!

May 18th, 2017

WOOSTER, OHIO — We had the pleasure on Monday of watching our geology seniors cross the stage and receive their diplomas. It happens every year, of course, and every year is special. Above is an image of most of the class taken in September as they started their last year at Wooster.

We were delighted that Wooster Geologist Helen Siegel (’17) earned the opportunity to speak at the commencement ceremony. (Image by ace College photographer Matt Dilyard.) She was a spectacular representation of her graduating class. She earned summa cum laude, Honors in Independent Study, the Jonas O. Notestein Prize, the Phi Beta Kappa Prize, and just about every award offered by the Geology Department itself. She is off to Yale on a full ride. Well done, Helen.

Sarah McGrath (’17) was another summa cum laude geology graduate; Clara Deck (’17), Annette Hilton (’17) and Chloe Wallace (’17) earned magna cum laude. It was a remarkably talented class — we’re proud of every student.

 

What is a clean lab?

May 16th, 2017

Chapel Hill, NC – Ben Kumpf (’18) and I are at the University of North Carolina at Chapel Hill to use their lab facilities for isotope analysis. We’re working with small amounts of sample and the instrument has a high degree of analytical precision and sensitivity, so all of our sample preparation occurs in the class-1000 clean lab. A clean lab is a room that is specifically designed to limit the amount of airborne contaminants. Special air filters and air distribution systems keep the environment clean so that we can minimize contamination while we separate and purify the isotopes.

Clean labs are classified based on the amounts of specifically sized particles allowed in a cubic meter (~35 cubic feet) of air. If we sample a cubic meter of air in the class-1000 lab and measure the amount of particles that are 5 microns in diameter, we would count no more than 293! For comparison, human hair has a diameter of about 50 to 100 microns, so we’re talking about really tiny bits of airborne dust. Class-1000 refers to Federal Standard 209E, where class-1 is the cleanest space and class-100,000 is the dirtiest (but still pretty darn clean). Federal Standard 209E has been replaced by International Organization for Standardization ISO 14644-1 standards. The new standards include one dirtier and two cleaner classifications and are numbered ISO-1 to ISO-9. Class-1000 is equivalent to ISO-6. UNC Chapel Hill also has a class-100 (ISO-5) clean lab where they process zircons for U-Pb dating.

Before we enter the clean lab, we gear up in the gowning room. The garments are designed to protect the wearer and minimize contamination from the wearer’s body. We wear standard lab safety attire, like glasses, gloves, and a lab coat. We also remove our shoes and exchange them for designated (comfy) slip-on shoes that only go in the clean lab.

Ben Kumpf (’18) models the clean lab outfit, complete with matching Carolina Blue accents. I see a theme.

Let the summer research commence!

May 15th, 2017

Chapel Hill, NC – As the College of Wooster Commencement ceremony was just finishing, our rising seniors were starting their summer research. Ben Kumpf (’18) and I are visiting the labs in the Department of Geological Sciences at the University of North Carolina at Chapel Hill. We are using their Isotope Geochemistry Lab to measure Sr-Nd-Pb isotopes of pillow lavas from our study site in northern British Columbia. The first step in the process is to dissolve our rock powders using several strong acids. Fortunately, we were able to send some of our samples in advance, and the good folks here at UNC dissolved about half of our samples for us.

Ben Kumpf (’18) went straight from his flight to the lab and is already hard at work. He measured portions of the dissolved samples into new vials so that we can prepare them for Sr isotope analysis. The dissolved samples will be made into solutions that we’ll use tomorrow.

Look for our posts in the following week to learn more about how isotopes are analyzed and what we hope to learn.

Wooster’s Fossils of the Week: Belemnites (Jurassic of Wyoming)

May 12th, 2017

This week’s fossils are among the most recognizable. They certainly are popular in my paleontology courses because no one has ever misidentified one. Belemnites (from the Greek belemnon, meaning javelin or dart) were squid-like cephalopods that lived in the Jurassic and Cretaceous Periods. You would never guess their original appearance from the fossils above. These are guards or rostra, internal hard parts that look nothing like the external animal. They are often found in large accumulations called “belemnite battlefields” (Doyle and MacDonald, 1993).
The above image shows a remarkable fossil belemnite in the State Museum of Natural History, Stuttgart, Germany (courtesy of User Rai’ke on Wikimedia). It shows their squidy form and ten equal-sized arms studded with little hooks for holding prey. They probably ate small fish and invertebrates.
The guard or rostrum is solid calcite at its distal end with a phragmocone (chambered shell) at the other. This phragmocone is only rarely preserved. The rostrum above is from the Zohar Formation (Jurassic) of the Golan in northern Israel near Neve Atif.

Belemnites have played an important role recently in sorting out Mesozoic climate change. Their solid calcitic rostra are ideal for examining stable isotopes that fluctuated with water temperature. Dera et al. (2011) showed that the Jurassic had significant climate variations based on the isotopes in belemnite fossils.

Belemnites have a long history in folklore. The English called them “thunderbolts” because they thought they were formed by lightning strikes. The Scottish knew them as “botstones” that cured horses of various ailments. The Swedish thought they were “gnome candles”. The Chinese called them “sword stones”. Much more prosaically, the belemnite is the state fossil of Delaware.
An engraving of belemnite rostra by Captain Thomas Brown (1889).

References:

Brown, Captain T. 1889. An atlas of fossil conchology of Great Britain and Ireland. With descriptions of all the species. Swan Sonnenschein & Co.

Dera, G., Brigaud, B., Monna, F., Laffont, R., Pucéat, E., Deconinck, J-F., Pellenard, P., Joachimski, M.M., and Durlet, C. 2011. Climatic ups and downs in a disturbed Jurassic world. Geology 39: 215–218.

Doyle, P. and MacDonald, D.I.M. 1993. Belemnite battlefields. Lethaia 26: 65-80.

[Originally published on November 20, 2011.]

The 30th Annual Keck Symposium and the Importance of Presentation in the Undergraduate Research Experience

May 11th, 2017

Middletown, CT – Wesleyan University recently hosted the 30th annual Keck Symposium. The Keck Symposium is one of the key features that separates Keck projects from other types of undergraduate research experiences. Most other REU programs are confined to the summer, but Keck projects continue through the following academic year and culminate in the Symposium. Research groups reunite to synthesize their individual results and present their work to a broader scientific community. The Symposium is also a best practice and an essential part of the undergraduate research experience. By presenting their research, students transition from private to public discovery and contribute knowledge to the scientific discourse. They develop confidence in their abilities and advance their independence as scientists (Lopatto, 2009).

Wooster Geologists, Andrew Conaway (’17), Chloe Wallace (’17), and Meagen Pollock are happy passengers headed to the Keck Symposium.

The Keck Symposium format involves two sessions of oral presentations followed by poster presentations. With coffee and muffins in hand, the Keck Iceland group is ready for the morning session.

Each research group provides an overview of their projects. Students present their work in a brief 5 minutes. Andrew Conaway (’17) tells the audience about the history of land use around the Wisconsin lakes that he studied.

The oral sessions are followed by poster sessions, where the students can discuss their work in detail. Andrew Conaway (’17) talks about his research on magnetic susceptibility in lake cores.

Chloe Wallace (’17) discusses her research on volatile contents of pillow lavas from a subglacial ridge in southwest Iceland.

Team Iceland celebrates the end of our poster session with a final group photo. The Symposium also provides an opportunity for faculty to catch up and network. It’s an important professional development opportunity, particularly for early-career faculty.

Another important thing that happens at the Keck Symposium is the review of copy-edited short contributions. Each student writes an extended abstract of ~2500 words and 5 figures, which is compiled and published in a Symposium Volume. Team Iceland goes through their short contributions one last time at the lunch break.

It’s an intense weekend, but the smiles on our faces at the end of it all (despite the early morning flight) show that it’s worth the effort.

Wooster’s Fossil of the Week: a medullosalean pteridosperm (Upper Carboniferous of northeastern Ohio)

May 5th, 2017

It is time we had another fossil plant in this series. The above specimen is Neuropteris ovata Hoffmann 1826, a relatively common bit of foliage in the Upper Carboniferous of North America. This is a pteridosperm, more commonly known as a seed fern. They weren’t really ferns at all but fern-like plants with some of the first real seeds. They are usually reconstructed as trees, but were also known to be bushy or even like climbing vines.

The taxonomy (naming system) of fossil plants can be very complicated because different plant parts were given different names at different times. A single plant species, then, could have a list of names for its foliage, bark, roots, seeds, etc. The name Neuropteris usually thus refers to the leaves of this particular pteridosperm.

Neuropteris ovata is famous for its use in studies of the distribution of stomata on its leaf surfaces. Stomata, sometimes called guard cells, regulate gas exchange and moisture retention in vascular land plants. The density of stomata on N. ovata leaves in the Late Carboniferous may reflect changes in carbon dioxide levels and the expansion and contraction of tropical forests (Cleal et al., 1999).

Neuropteris ovata was named by Friedrich Hoffmann (1797-1836), a Professor of Geology at the University of Berlin. I wish I knew more about him because not only did he do considerable paleobotanical research, he was also well known for his work on volcanoes in Italy. You don’t see that combination very often!

References:

Beeler, H.E. 1983. Anatomy and frond architecture of Neuropteris ovata and N. scheuchzeri from the Upper Pennsylvanian of the Appalachian Basin. Canadian Journal of Botany 61: 2352-2368.

Cleal, C.J., James, R.M. and Zodrow, E.L. 1999. Variation in stomatal density in the Late Carboniferous gymnosperm frond Neuropteris ovata. Palaios 14: 180-185.

Hoffmann, F. 1826. Untersuchungen über die Pänzen-Reste des Kohlengebirges von Ibbenbühren und von Piesberg bei Osnabrück. Archiv für Bergbau und Hüttenwesen 13: 266-282.

Zodrow, E.L. and Cleal, C.J. 1988. The structure of the Carboniferous pteridosperm frond Neuropteris ovata Hoffman. Palaeontographica Abteilung Palaophytologie 208: 105-124.

[Originally posted on October 23, 2011.]