As always, a healthy contingent of faculty and student researchers will be representing the University of Cincinnati at the Geological Society of America (GSA) annual conference, Oct. 22 to 25. This year, for the 118th annual meeting, representatives from the UC Department of Geology will be joined by colleagues from the College of Engineering, as well. UC’s presentations represent the range of geology specialties at the University of Cincinnati, especially the paleontology program — which U.S. News & World Report has ranked as 7th in the nation.
Within the UC Department of Geology, it’s difficult to say what the highlight of their year is because they have so many. (Check out their 10 reasons to study geology at UC.) However, for most geology programs, the highlight of the year is the annual GSA conference. This year, folks from UC are listed 33 times on 18 papers or posters. Many are expected to attend along with 6,200 of their closest geoscientist friends and colleagues.
|Austin Hendy and a geologist's best friend, the rock pick.|
“Essentially, I am investigating whether the fossil record of the tropics yields considerably more diversity (numbers of marine invertebrate species) than that of cooler parts of the Earth (temperate) regions,” explains Hendy. “The existing paradigm is that the tropics are far greater in diversity than temperate regions. This is known as the ‘latitudinal diversity gradient,’ and it’s largely based on observations of the modern marine environment, which is rather different from in times past. An important question in paleontology at the moment is whether this trend can be detected in the fossil record, and how far back in Earth's history can it be detected. This has implications for how we estimate global diversity trends through the Phanerozoic (the past 500-odd million years).”
This will be Austin Hendy’s fourth GSA presentation. He stresses what an important event this is for students at UC each year. “With GSA being the pre-eminent geology conference, it is an opportunity for us to present the progress of our research and important findings to our peers and the wider geology community. The feedback, criticism and job opportunities that we receive are beneficial.”
Fellow student Jay Zambito is also not a newcomer to the annual GSA, having presented in past years. This year he will be presenting “A Test of Ambocoeliid (Brachiopoda) Spinosity as an Adaptation for Soft Substrates Using Abundance Patterns Through Transgressive-Regressive Cycles and within Pyritic Shale Beds.”
“My research focuses on relating the presence and abundance of a family of brachiopods (shelled invertebrates) to sediment firmness and general sea level fluctuations,” he says. “The brachiopods I am studying occur both with and without spines, which appear to be adaptations for staying on top of soft sediments. Implications include the use of the presence of certain species of brachiopods as general indicators for sea level rise and fall in the Middle Devonian Appalachian Basin of New York.”
|Colby Smith checking out a rock on top of lateral moraine.|
|Colby Smith at Nevado Sajama. Terminal moraines can be seen at the foot of the mountain.|
Master's student Tracy Brockman used crystal size distribution analysis of basaltic lava from the 1985 Kilauea eruption to determine the magma residence time. Magma residence time is roughly the time spent in the magma chamber. It has implications for input and output. When magma reaches the surface, it is called “lava.” Crystal sizes of plagioclase feldspars from the 1985 flow at the Royal Gardens area have been measured in the Image Analysis lab and data have been analyzed. A plot of the number of plagioclase crystals per unit size per volume against crystal size yields a linear relationship. Using the published growth rate for plagioclase, the slope equation gives 2.69 years as the magma residence time.
“Since the ongoing eruption of Kilauea started in 1983 and my samples are from the 1985 flow, 2.6 years’ residence time based on my CSD analysis agrees very well with the residence time of the Kilauea magma,” says Brockman.
Last year's GSA Schlemon Scholar and UC doctoral student Ana Londono will be presenting "Erosion Evolution in Arid Environments Derived from the Study of Pre-Columbian Agricultural Terraces in Southern Peru." Londono will be presenting results from the last two summers that she has spent on the hot slopes of Peru.
|Ana Londono near Moquegua, Peru.|
UC professor and renowned sedimentologist Warren Huff is involved in two activities at GSA. “I'm co-author with Tom Lowell and five students on a poster entitled, ‘Sedimentary processes associated with deglaciation near Sioux Pond Lookout, northwest Ontario.’ An undergrad, Jim Milawski, is the senior author and is responsible for putting the poster together,” says Huff. “This presentation is the outcome of a spring quarter seminar that I conduct every year. We collaborated this year with Tom Lowell on studying a lake sediment core from Canada that penetrates the boundary between the end of the ice age and the beginning of warm climate conditions. Every student has a particular job to do. At the end of the term, we compile our data and prepare a presentation for the annual GSA meeting in the fall. In this particular project, we studied the climate transition and noted a profound change from almost no organic matter in the ice-age sediments to very abundant organic matter in the post-glacial sediments. So this is a powerful record of the last major climate shift to occur on Earth, about 10,000 years ago.”
Huff will also present a workshop on the importance of radioactive age measurements in the calibration of Earth events with co-convener Tom Olszewski from Texas A&M University.
Associate Professor Tom Algeo is also another old hand at GSA presentations. “I have been giving professional talks for about 20 years,” he says. The first GSA talk this year is “Milankovitch Cyclicity in the Ohio and Sunbury Shales: Astronomical calibration of the Late Devonian-Early Carboniferous Timescale” with authors Algeo, Linda A. Hinnov, and D. Jeffrey Over.
|Devonian shales in Kentucky (Photo by Tom Algeo)|
Algeo also co-authored “The Permian-Triassic Boundary at Nhi Tao, Vietnam: Evidence for Recurrent Influx of Sulfidic Watermasses to a Shallow-Marine Carbonate Platform” with Yanan Shen, Timothy W. Lyons, Brooks B. Ellwood, Harry Rowe and Tonggang Zhang.
“The Permian-Triassic boundary records the largest mass extinction (~90% of all species) in Earth history. The trigger for this extinction event may have been a massive volcanic eruption, but geochemical evidence shows that chemical changes in seawater were important also,” he says. “This study documents repeated incursions of toxic, sulfidic deep-ocean waters onto shallow-marine carbonate platforms, with the first and largest incursion coinciding with the mass extinction horizon. The significance of these observations is that they may record large-scale overturn of the global ocean following an extended interval of stagnation during the Late Permian.”
Storms and Climate Cycles in Ancient Tristate Seas
Next time you are driving up the big hill on I-75 or I-471 in Kentucky Prof. Carl Brett wants you to take a look (carefully, no accidents please!) at those great gray road cuts.
"These cuts in the Kope Formation are a window on the past and a natural laboratory for studying such fascinating things as ancient hurricanes and global change in the Ordovician Period, 450 million years ago, when the Tri-state area lay south of the equator covered by subtropical seas," Brett says. "During that time, muds were pouring out of newly uplifted precursors of the Appalachians in eastern North America. A glance will show that there are somewhat regular rhythms: bands of hard limestone that protrude from the weathering gray clay banks. These oscillations between limestone and mudstone (shale) have been the source of considerable interest and debate. Limestones made of shells and other animal and plant skeletons don’t generally form on muddy sea bottoms, yet the Kope Formation is up to 80% mudstones: hence, the bands form something of a paradox."
Do the alternations between shell rich limestones and muds tell us something about ancient climate change? Many geologists would argue that they do.
"One widely held view postulates that the limestones represent periods of increased hurricane activity on the seafloor," says Brett, "when the shallow seabed was literally churned and muds suspended and taken away leaving behind a residue of shells. In this model muds were typically considered as background sediments formed during calm times, while the limestones were thought to record one or a few violent storm events."
However, new evidence — discussed by UC Professor Carlton Brett and colleagues at this week’s Geological Society of America meeting in Philadelphia — indicates that hurricanes were ongoing during deposition of both the muds and the limestones and that the limestone bands (which he has traced one by one from Cincinnati to Maysville, Ky.) may have a more important meaning.
"Rather than representing quiet background conditions, many of the mudstones demonstrably represent rapid dumping of mud following severe storms while some limestones represent periods of low influx of sediment, thus turning the older hypothesis inside out. In turn, the lack of sediment washoff from the eastern mountains may record a still more basic signal: cycles of climate (wetter to drier periods) and/or minor fluctuations of sea level of a few meters."
|Meghan Welch sampling with Tammie Gerke supervising and the dog doing sampling of its own.|
"The regular cycles seen in our local rocks provide evidence for climatic oscillations that may, in turn, owe their existence to wobbles and changes in tilt Earth’s axis that may have been going on like clockwork through our planet’s history," says Prof. Brett. If so, these simple alternating ledges and slopes may eventually provide something like a geological metronome for parsing out Earth’s history at a fine scale.
Established in 1888 in Ithaca, New York, the Geological Society of America (GSA) is a global professional society with a growing membership of more than 19,500 individuals in over 85 countries. It is an offshoot of the American Association for the Advancement of Science. In fact, GSA’s very first “annual” meeting was at the end of the AAAS meeting in August 1889 in Toronto. A few presentations were made and the governing documents were drawn up. On December 27, 1889, GSA held its second annual meeting (yes, in the sae year) in much the same format that is followed today.