Archive for February, 2019

Advice from a Grad Student

February 11th, 2019

I caught up with Wooster Geologist Clara Deck (’17) at the AGU meeting in December. Clara is a grad student who has been doing exciting research on glaciers. I asked her to tell us a little about her research and how her experience at Wooster helped her prepare for grad school. She discovered that her research has called on concepts and skills from Structural Geology and Computer Science. Stories like Clara’s motivated us to design our Geology and Environmental Geoscience majors to be flexible, allowing students to explore their interdisciplinary interests and pursue their passions. We’ve also added computational methods to our curriculum. Thanks, Clara, for the inspiration!

Guest blogger: Clara Deck (’17)

Clara Deck on Jarvis Glacier in the East Alaska Range, August 2018.

As a master’s student at the University of Maine’s School of Earth and Climate Sciences, my research has focused on dynamic processes of Antarctic Ice Shelves. Glacial ice in Antarctica flows outward to sea and creates tabular masses called ice shelves, which are tethered to about 75% of the continent’s coastline. These floating ice shelves are critical to the stability of land-based ice because they keep glaciers from flowing freely into the ocean and contributing to global sea level rise. The Ross Ice Shelf (RIS) is the largest in Antarctica and supports the flow of the West Antarctic Ice Sheet, which contains an ice volume of over three meters of global sea level equivalence if it were to enter the ocean. At the western coastal margin of RIS, ice is continuously dragged along protruding bedrock features and becomes deformed, exhibiting large cracks or rifts over a kilometer in length which can be seen in satellite imagery. If a rift were to propagate across RIS, the ice shelf could break up and allow land ice to flow seaward much more quickly. My thesis work aims to characterize the origin and evolution of rifts on RIS using three-dimensional modeling.

Mapping a crevasse on Jarvis Glacier.

I never expected this, but Structural Geology was one of the most helpful classes at Wooster to help me prepare for my graduate work on glaciers and ice shelves. The same stresses at play in tectonics are important within ice, just on a different temporal and spatial scale. I wish I had known that these processes, ductile and brittle, from the micro- to macro-scale, were also applicable to ice!

Evolution of rifts on the Ross Ice Shelf with ice flow, shown through optical imagery from Landsat 1, Landsat 4, Landsat 7, and Sentinel 2, respectively.

At Wooster I took CSCI 100 and 110, classes in Python and C computing languages. These were helpful to learn basics in computing syntax, but it was a steep learning curve in graduate when using computing for glaciological applications. It would have been really useful to have had some background in modeling and writing code related to geological physical processes. I’ve been excited to hear that some modeling is now incorporated into some courses in the Earth Sciences department. Another surprise when starting my master’s was how much calculus is involved in glaciology. I took calc 1 and 2 at Wooster, but I still had quite a bit to catch up on. For students going into climate change or cryospheric studies, I think learning quantitative analysis is just as important as the qualitative side.

Model of a floating ice tongue showing the differential stress field due to buoyancy force from underlying marine water. Solved using a particle approximation of Navier-Stokes for forces associated with water and finite element analysis for high viscosity ice. This model explores the connection of ice shelf deformation with upstream grounding line processes.

Overall, I feel that Wooster Geology prepared me very well for my graduate studies. Because of Sophomore Research and I.S., I had a lot of experience in independent research, seeking out my own resources, and laying out my own goals and timeline. All those skills have helped me be successful so far, because I’ve found that much more responsibility is put on the student at the graduate level. I’m glad I pursued grad school and I hope to defend my master’s thesis this spring!

Bringing three new Silurian bryozoan species into the world

February 10th, 2019

I love being part of the scientific process of naming new organisms and placing them into the grand narrative that is the history of life. It is a kind of rescue — retrieving species from oblivion by giving them identities. Carolus Linnaeus, the father of taxonomy, said it well:

The first step in wisdom is to know the things themselves; this notion consists in having a true idea of the objects; objects are distinguished and known by classifying them methodically and giving them appropriate names. Therefore, classification and name-giving will be the foundation of our science.

The bryozoans described in this post are from a project led by my very accomplished bryozoologist friend Andrej Ernst at the University of Hamburg, Germany (above). In the summer of 2015, Andrej and I met up with our colleague Carl Brett (University of Cincinnati) to collect bryozoans from the Lower Silurian (Aeronian) of western New York. My fieldwork was supported by a grant from the Luce Fund at The College of Wooster. We had a very productive time and saw much geology and paleontology, as you can see from these August 2015 blog posts. That fieldwork was followed by Andrej’s prodigious lab work with the bryozoans. The results have now appeared in the Journal of Paleontology.

The abstract: Thirteen bryozoan species are described from the Brewer Dock (Hickory Corners) Member of the Reynales Formation (lower Silurian, Aeronian) at the locality Hickory Corners in western New York, USA. Three species are new: trepostomes Homotrypa niagarensis n. sp. and Leioclema adsuetum n. sp. and the rhabdomesine cryptostome Moyerella parva n. sp. Only one species, Hennigopora apta Perry and Hattin, 1960, developed obligatory encrusting colonies whereas the others produced erect ramose colonies of various thicknesses and shapes: cylindrical, branched, and lenticular. Bryozoans display high abundance and richness within the rock. This fauna is characteristic of a moderately agitated environment with a stable substrate. The identified species reveal paleobiogeographic connections to other Silurian localities of New York as well as Ohio and Indiana (USA) and Anticosti (Canada).

The top photo in this post is one of the new bryozoans, the trepostome Homotrypa niagarensis. The images are from Figure 8, with the caption: (2) branch oblique section, holotype SMF 23.470; (3) rock thin section with transverse and oblique sections of branches, holotype SMF 23.472; scale bars are 3 mm and 5 mm respectively.

Above is the new trepostome Leioclema adsuetum. The image is from Figure 10, with the caption: (1) longitudinal section of exozone showing autozooecia, mesozooecia, and acanthostyles, paratype SMF 23.553; scale bar is 0.5 mm.

This is the third new species, the cryptostome Moyerella parva. The images are from Figure 11, with the caption: (3) longitudinal section of a colony segment with a pointed base and widened proximal part showing medial axis and autozooecia, holotype SMF 23.559; (4) tangential section showing autozooecial apertures, tubules, and tectitozooecia, holotype SMF 23.559; scale bars are 0.5 mm and 0.2 mm respectively.

The paper is about more than these new species, of course. There are other bryozoans assessed, and Carl Brett’s stratigraphy section is magnificent and a new resource for the area. The new taxa, though, are worth celebrating by themselves.

Thank you to Andrej and Carl for being such good colleagues. I hope we return to the Silurian of western New York for more work.

Reference:

Ernst, A., Brett, C.E. and Wilson, M.A., 2019. Bryozoan fauna from the Reynales Formation (lower Silurian, Aeronian) of New York, USA. Journal of Paleontology, doi.org/10.1017/jpa.2018.101.

Sometimes a Cold Snap is Just a Cold Snap

February 7th, 2019

On Wednesday, January 30, 2019, The College Wooster closed due to cold. This cold snap was felt across much of the central and eastern USA. The message Wooster staff and faculty received included this statement:
“The National Weather Service is forecasting daytime temperatures tomorrow between -3 and -7 degrees Fahrenheit, and wind chills of -25 to -30. In these weather conditions, exposed skin can begin to show signs of frostbite in as little as 10 to 15 minutes outside.”

However, in the past week, I’ve heard diverging narratives from people across the eastern USA about their experience. Some lament that this was horrible weather, the worst ever — how can climate change be real? Others lament that it used to get much colder — we have it easy today because of global warming. So what’s the truth? 1) Was Wooster’s cold spell out of the ordinary? 2) Is winter not as harsh as (or harsher than) it used to be? 3) Is climate change to blame?

1) Last week’s cold was not out of the ordinary.

There’s two ways to think about how cold it was.  One is that the daily high was only 9.6°F, which is frigid — it never topped 10°F. Another is that the daily low was -6.0°F, and that occurred while students would have been walking to classes in the morning. I can’t speak much to the wind chill because the OARDC station is too far from campus to give an accurate assessment.  Wind varies a lot more temperature from place to place, so it’s hard to know exactly how bad the wind chill was for any random person walking with exposed skin outside.  For temperature, though, the weather forecast was spot on.

Figure 1: The distribution of the annual low temperature in Wooster (the lowest daily low) from 1900 to 2018, with 2019 marked.

That temperature, however, was not exceptional.  Funny enough, January 22, 2019 actually had a lower low of -7.2°F — it just wasn’t as windy. In Wooster, the average annual low temperature since 1900 is -7.6°F. The average lowest daily high is 11.0°F. Our 2019 is currently right in line with those numbers (although the winter is not yet over).

2) The coldest days might be getting less severe.

This is actually a tricky one to answer. If you look at the coldest temperature recorded each year at the OARDC, nearly every year before 1930 had at least one day in which the temperature fell below 0°F — but not so from 1930 to 1960.  The coldest cold was above 0°F about in about 25% of the years in that second period.  From 1960 to 1990, the reliable sub-zero temperatures returned.  Since 1990, the annual coldest day has been less severe again on average.  In other words, if you only look back to 1960, yes, the worst days have been getting less severe.  But if you look back to 1900, the last 120 years suggest that Wooster still gets plenty of cold.  So if you were born in the 1950s, no, the new generation doesn’t have it easier, but they may be more sensible about preventing frostbite.

Figure 2: Time series of the the lowest daily low temperature (the coldest temperature each year) in Wooster from 1900 to 2019 (so far).

3) There’s not a clear climate change signal here.

The problem with evoking climate change is that weather extremes are by definition rare, so it’s hard to pinpoint the immediate cause of local-scale weather extremes to long-term, global-scale warming.  There is some evidence out there that the polar jet stream (a.k.a. the “polar vortex”) is becoming more erratic as the world warms, leading to more days like January 30 when the Arctic Ocean is warmer than Minnesota, but that is not settled science. Plus, there’s no clear trend with this particular measure. In other words, it’s premature to blame climate change for every weather event you don’t like.