Mark Wilson February 20th, 2015
We haven’t had a local fossil featured on this blog for awhile. Above is an external mold of the spiriferid brachiopod Syringothyris typa Winchell, 1863, from the Logan Formation (Lower Carboniferous, Osagean, about 345 million years old) of southeastern Wooster, Ohio. The outcrop is along the onramp from north Route 83 to east Route 30. Older Wooster geologists may remember this area was called “Little Arizona” because of the large roadcuts made for a highway bypass that was never completed. That original outcrop was destroyed several years ago, but the same rocks are exposed in this new section. This is the area where Heather Hunt (’09) did her Senior Independent Study work, and long before her Brad Leach (’83) worked with the same fossils.
The Logan Formation is primarily fine sandstone, with some subordinate conglomerates, silts and shales. It was likely deposited in the proximal portion of a prodelta at or below wavebase. The fossils in the Logan are mostly these large Syringothyris and the bivalve Aviculopecten, along with scattered crinoids, gastropods, bryozoans, nautiloids and ammonoids. This fauna needs more attention. Funny how the fossils in your own backyard are so often ignored.
This brachiopod was first buried in sediment and then the shell dissolved away, leaving an impression behind. Since it is an impression of the exterior of the shell, it is called an external mold. Curiously, all the external molds (and the internal molds as well) in the local Logan Formation have an iron-rich, burnt orange coating much finer than the fine sand matrix. This means that details are preserved that are of higher resolution than the matrix alone would allow. In the case of this fossil, that coating extended down into long, narrow borings in the shell, casting them (see below).
These borings are odd. Most of them are parallel to the ribs (plicae) of the brachiopod, and appear to have been excavated from the shell periphery towards its apex. This was in the opposite direction of brachiopod shell growth. I suspect they were made by boring annelid worms that started at the growing edge of the shell where the mantle ended. These traces need attention, like most other aspects of this local fossil fauna.
Ausich, W.I., Kammer, T.W. and Lane, N.G. 1979. Fossil communities of the Borden (Mississippian) delta in Indiana and northern Kentucky. Journal of Paleontology 53: 1182-1196.
Bork, K.B. and Malcuit, R.J. 1979. Paleoenvironments of the Cuyahoga and Logan formations (Mississippian) of central Ohio. Geological Society of America Bulletin 90 (12 Part II): 1782-1838.
Leach, B.R. and Wilson, M.A. 1983. Statistical analysis of paleocommunities from the Logan Formation (Lower Mississippian) in Wayne County, Ohio. The Ohio Journal of Science 83: 26.
Mark Wilson August 30th, 2014
What a fine group of geologists we had at the first meeting of the College of Wooster Geology Club this week. We have an ambitious year ahead of us with outside speakers, student presentations, course field trips, and our biennial Mojave Desert Spring Expedition. Our number of geology majors has grown significantly as well, which is delightful for the faculty and staff. This great photo was taken by our departmental chair, Greg Wiles. Too bad he couldn’t have been in his own expertly composed image.
Links to our course offerings this semester can be found on our Geology Department Courses page.
mpollock June 25th, 2014
Guest Bloggers: Julia Franceschi and Mary Reinthal
A little over a week ago at Spoon market in downtown Wooster, we met our research collaborators from Dickinson College. Although it was the first time we met rising junior Liz Plascencia and Dr. Ben Edwards, after a little talking and a lot of food, it seemed like we had known them for years.
It turns out Liz is just like us: she loves the outdoors, she doesn’t want to get eaten by a bear in the field (*potentially*) and, of course, she loves rocks. It was a good sign for the weeks to come, because together, we prepared mentally and physically for the impending two-week trip to British Columbia, Canada (maybe not mentally, but we definitely went to the gym together).
PREP WORK/ WHY WE ARE GOING:
Pillow Ridge in British Columbia has exceptional pillow lava exposure. These pillows were created by subglacial volcanic features, and were subsequently sheared by a retreating glacier, thus making for an excellent work site to study these lavas. It is our hope to observe, characterize, and model the pillow-dominated area for reconstruction of the stratigraphy, and study a variety of pillow samples for geochemical analysis.
So in the weeks preceding the trip to Pillow Ridge, Wooster students Adam Silverstein, Mary Reinthal, Julia Franceschi (and of course Liz) did a lot of preparation from previously collected samples from the area. We made pressed pellets, fused glass beads, picked glass chips for volatile analysis. It wasn’t all physical work. Sometimes we read papers on pillow lavas for three hours in Broken Rocks over coffee with Dr. Pollock. Sometimes we did equipment checks and learned how to use a Brunton compass. It was a very “independent minds working together”-type atmosphere, but everyday was a lot of fun. See below for an exciting array of pictures portraying the lab work.
T-MINUS 24 HOURS:
Having accomplished a lot in the past couple of weeks together, we are now preparing in the last hours to fly out to Vancouver. Together we make an interesting team. We range in field experience from beginner to advanced. We have put in a lot of work, and are now ready for “roughing it” in the field. We have our tents packed and our ugly sweaters prepared. Ready or not, British Columbia, the Wooster and Dickinson crew are coming. And we are prepared to make memories and come back more knowledgeable than when we left (or at least with better thigh muscles/definition). Here’s to a new adventure!
mpollock June 24th, 2014
It’s safe to say that time truly does fly. Seemingly having know Mary and Julia for years, I am reminded that my arrival to The College of Wooster was a little over a week ago.
Mark Wilson February 16th, 2014
GAINESVILLE, FLORIDA–Steph Bosch (’14), Lizzie Reinthal (’14) and I flew out of icy Ohio this weekend to attend the 10th North American Paleontological Convention in warm, sunny northern Florida. The students jointly presented the beautiful poster above on their Independent Study projects in the Matmor Formation (Middle Jurassic, Callovian) of southern Israel. It was very well received, especially with the addition of fantastic scanning electron microscope images of bryozoans produced by our colleague Paul Taylor at the Natural History Museum in London.
Here’s a crowd scene from the first poster session at NAPC. If you look closely in the center, you’ll see two Wooster alumnae who are prominent paleontologists. Can’t swing a cat at a paleo meeting without hitting Wooster Geologists.
This is a nondescript image of our hotel and convention center in Gainesville. I show it only to marvel in the blue, blue sky and perfect temperatures. We are on the University of Florida campus near the Florida Museum of Natural History. The paleontology staff at that museum is sponsoring this meeting — and they are doing an extraordinary job made more complex by the absence of about a third of the participants still snow-bound in the north. We escaped through a window of clear weather in Ohio.
Mark Wilson January 10th, 2014
WOOSTER, OHIO — Above you see Wooster Team Israel 2013 veterans Lizzie Reinthal, Steph Bosch and Oscar Mmari (whom I seem to have caught with his mouth full). Since I’m starting a research leave this semester, we took a last chance to have an evening meeting with pizza, lemon dessert, popcorn and a movie in the warm Wilson living room. It is wintry Ohio outside, but we all have memories of the beautiful Negev:
And what was the movie? You really don’t need to ask, do you?
Mark Wilson October 28th, 2013
DENVER, COLORADO–It is a tradition at the annual GSA meeting to have a Wooster Geologists alumni gathering. Here is this evening’s happy crew of current students, faculty and alumni — or at least a snapshot of a continuum of people coming and going. We missed Dr. Greg Wiles, who could not be with us this year. Thirty people were present at some point.
Mark Wilson October 28th, 2013
DENVER, COLORADO–This afternoon Dr. Meagen Pollock presented a poster at the Geological Society of America entitled: “The history, current best practices, and future trajectory of the Independent Study (I.S.) program at The College of Wooster“. In this work, co-authored with the other Wooster geology faculty members, Dr. Pollock outlined the structure of I.S. in geology, emphasizing the philosophy behind what we do. It was well attended, from what I saw, and started many interesting conversations about undergraduate research. An advantage of presenting this poster here is that there were several Wooster I.S. students nearby showing their research results.