Spring 2014 Colloquia

January 13: Henry Loope, Indiana Geological Survey. Title: Chronology and paleoenvironmental significance of Eolian sand activity south of the Laurentide ice sheet during the last glacial perios, upper Mississippi River basin.

Abstract: Wind-blown sediments of the North American midcontinent provide important information regarding past climate and terrestrial processes during the Quaternary. An accurate chronology of eolian activity is needed to compare with other records of paleoenvironmental change, including advance/retreat of the Laurentide Ice Sheet and paleoecological records of vegetation change. This project employs optically stimulated luminescence (OSL, aka optical) dating to determine the depositional age of eolian sand within the Upper Mississippi River basin in order to reconstruct the timing of past changes in surface sand availability and atmospheric circulation. Twenty nine optical ages on eolian sand range in age from ca. 20 to 13 ka with the majority of ages clustered around 16 ka. The bulk of ages fall near the end of an interval documented by previous research within the study area indicating periglacial mass wasting between ca. 23 and 14 k cal yr BP based on radiocarbon ages on wood and gastropods from colluvium. Significant retreat of the Lake Michigan and Des Moines Lobes of the Laurentide Ice Sheet also occurred after 16 ka, and the final record of tundra-like vegetation and permafrost in the study area occurs near 16 ka. Optical ages on eolian sand from several distinct geomorphic settings, including fluvial (fill terrace) sediments from both glaciated and unglaciated fluvial catchments and colluvium derived from Cambrian sandstones overlap within error at ca. 16 ka, suggesting a regional eolian response rather than localized responses due to changes in sediment supply. I hypothesize that the regional eolian response is ultimately forced by changes in atmospheric circulation and surface conditions associated with the melting of permafrost.

January 20: Dr. Martin Luther King Day, no classes

January 27: Dr. Gregory Hempen Jahns Distinguished Lecturer URS Corporation. Title: Kaboom! (Or Whoosh?) AKA: Mitigating blasting impacts without diminishing effectiveness.

Abstract: Blasting is a viable way to loosen and move a large volume of rock or concrete quickly for excavation. When done properly, blasting also will minimize undesired impacts or damage.

Abstract: Blasting is an art that is not well understood by the public. Blasting is very effective in moving low-tensile materials (rock and concrete) that cannot be easily excavated mechanically. Blasting is effective because the chemical release of energy from the blasting agent results in detonation and in great gas-volume production in a very short time. The blaster uses empirical approaches and experience for the beginning blast design. The blaster modifies each successive shot pattern to reach the project’s objective within the contract’s limitations.

The three primary impacts due to blasting are flyrock, noise (airblast), and vibrations (or pressure waves in an aquatic environment). Sometimes, secondary effects from these primary impacts occur some distance away from the blasting zone. These primary impacts can be controlled by the blasting parameters used and, for some projects, additional mitigating measures. Usually, blasting is the only option, and it may be impossible to avoid all undesired secondary effects. The talk includes proven ways to mitigate unwanted secondary effects from unusual blasting projects. The example projects include quarry blasting’s possible disturbance of hibernating Myotis Sodalis (Indiana Bats), impacts on a planned natural-gas pipeline near an active quarry, removal of the Embrey Dam (Rappahannock River near Fredericksburg, VA), rock excavation near geologic hazards, and adverse impacts from blasting water-borne structures. Geophysical assessment of the site is required to understand wave passage and how vibratory, or pressure-wave, impacts may have damaging amplitudes beyond the blasting zone.

The example projects will illustrate how to mitigate human, environmental, geologic, and structural impacts without diminishing the blasting’s effectiveness. Key project steps include reviewing similar projects, estimating primary impacts, assessing potential secondary hazards, measuring primary impacts, and documenting important blasting parameters, including the blasting contract and blasting purpose. Many projects require some education of the owner (client), engineer-in-charge, blasting firm, local neighbors, and the public at large. Blasting can be done in a way that achieves the project’s goals without causing adverse impacts to surrounding areas.

February 3: Candidate talk

February 10: No Colloquium scheduled

February 17: Steve Goldsmith, Villanova. Title: The Role of Small Mountainous Rivers in the Global Carbon Cycle

Abstract: Fluxes of organic and inorganic matter between land and the coastal ocean are important components of global biogeochemical cycles, including the carbon cycle. However our understanding of the inputs (solutes, sediment, and organic carbon) via rivers and the magnitude of their overall delivery to the coastal ocean remains poorly constrained as most studies have focused on large temperate rivers, with measurements from tropical rivers being dominated by those from the Amazon. Over the last two decades, a growing number of studies have demonstrated that small mountainous rivers (SMRs) can collectively transport globally significant amounts of terrestrial materials to the coastal ocean, yet their hydrogeochemistry and the biogeochemical processes determining their character and controlling their fluxes are not well understood. This talk will attempt to address these knowledge gaps by evaluating the following: 1) the dissolved, particulate and organic carbon fluxes delivered to the ocean from a SMR during an intense aperiodic storm event (i.e., typhoon), 2) the relationship between physical and chemical weathering rates on SMRs characterized by varying uplift rates and lithology, and 3) water and sediment geochemical fluxes and CO2 consumption rates from SMRs underlain by andesitic-dacitic volcanism. Finally, a brief jaunt will be made into the small semi mountainous rivers of Pennsylvania to explore the role of recent natural gas extraction activities on the quality of streamwater.

February 24: TBA

March 3: Peter Crane, Yale University. Title: Early Cretaceous Plant Fossils from Mongolia and their Significance for the Evolution of Seed Plants

Peter has made important contributions to our understanding of plant evolution and its relationship to the evolution of the Earth and atmosphere. He has received many accolades for his work. He has previously held positions at the University of Chicago and the Field Museum of Natural History, he was Director of the Royal Botanical Gardens at Kew, he is a Fellow of the Royal Society and a foreign associate of the US National Academy of Sciences. Indeed, he is technically Sir Peter Crane because he was knighted in 2004 for his work on plant evolution. It is firmly believed that many of these accolades are due to the excellent training he received as a postdoctoral fellow at Indiana University-Bloomington in 1981-1982 where he worked with David Dilcher.

Abstract: Early Cretaceous fossil plants from Mongolia date from a critical interval in plant evolution just prior to the major mid-Cretaceous diversification of flowering plants. Fieldwork in 2011, 2012, and 2013 has identified several localities with exceptionally preserved paleobotanical material, studies of which are only just beginning. The Early Cretaceous flora is dominated by conifers of various kinds, which provide new information on the evolution of these important trees, but the flora also contains a variety of other seed plants. Some of these extinct seed plants belong to a clade (the BEG group) that includes extant Gnetales and their fossil relatives. The presence of the BEG group in many fossil floras from the northern hemisphere contributes to the growing evidence that these plants were a major component of certain kinds of Early Cretaceous vegetation. The ecological and phylogenetic significance of this group is only just beginning to be recognized.

March 10: Paola Passalacqua, University of Texas at Austin. Title: The Delta Connectome: Structure and transport dynamics of delta networks across scales

Abstract: Deltas are known to be fragile: anthropogenic disturbance (e.g., upstream sediment trapping due to dam construction, sediment mining, navigation structures, or accelerated subsidence due to oil or water extraction), natural subsidence, and eustatic sea-level rise are among the major causes of threat. The response of the system to these forcings can be dramatic and result in loss of human lives, economic resources, and environmental services. Yet, under the right conditions, deltas are also resilient, capable of adapting to a changing environment and recovering from damage caused by extreme events such as storms. Rich in ecosystem diversity and economic resources, deltas host approximately half a billion people; managing and preserving these dynamic centers of activity is imperative. One key aspect is how the delta network structure (here defined as topology and associated geometry) relates to its dynamics. Such relationships have been established in many fields, from metabolic networks and food webs, to neural interactions, but similar work on deltaic systems has yet to be developed. In this talk I will present the idea of the Delta Connectome, a research framework based on the general idea of a delta as a directed network of connected paths (physical, functional, and conceptual paths of process coupling) which interact continuously at a broad range of space and time scales and dictate system response to change. Specifically, I will show how the delta network structure carries the signature of dominant deltaic processes and vegetation. I will then focus on the hydrodynamics of deltaic systems and quantify their environmental controls.

March 17: No Colloquium, Spring Break

March 24: Christoph Irmscher, IU English Department. Title: Agassiz Matters (Or Not?)

AbstractL In this talk, I will revisit a foundational moment in the history of American science: Louis Agassiz’s legendary Lowell lectures of 1846. I will try to explain how the tireless proponent of the theory of the "Ice Age" succeeded in conquering American science and how and why he destroyed his reputation by reinventing himself as an expert in matters of race. I will draw on my recent biography of Louis Agassiz (Louis Agassiz: Creator of American Science, Houghton Mifflin Harcourt, 2013) as well as on new research for an edition of Louis Agassiz’s Introduction to the Study of Natural History (forthcoming from Springer in 2014).

March 31: Dena Smith, University of Colorado. Title: TBA

April 7: Dr. Isla S. Castañeda. Title: What biomarkers can tell us about past environmental conditions on Earth: A few examples from the Siberian Arctic and the African tropics

April 14: Sean Bemis, University of Kentucky. Title: Quaternary geologic controls on Denali fault strain-partitioning and the uplift of Mount McKinley.

April 21: Steve Graham, W.J. and M.L. Crook Professor, School of Earth Sciences Stanford University (Owen Award winner). Title: New views of an old continental margin: Great Valley forearc basin, Cretaceous, California. Professor Graham received his B.S. in Geological Sciences from Indiana University in 1972 and worked in both research and exploration geology at Chevron before joining the Stanford faculty in 1993.

Abstract: The Cretaceous Great Valley basin of central California has served as the type example of an ancient forearc basin since the advent of plate tectonics in the 1960s. Nevertheless, emerging technologies and access to subsurface data are rapidly changing perceptions of the basin. The Great Valley basin is proving to be a remarkable archive of the evolution of the California convergent margin, including morphotectonic elements of the system that long since have been destroyed by erosion. Specifically, petroleum industry seismic reflection data allow definition of the basin’s stratigraphic architecture, which in turn informs depositional systems analysis and understanding of the basin as an open vs. closed system. Age determination of detrital zircon is revolutionizing views of the Great Valley forearc, including its chronostratigraphy and morphologic evolution of the arc, from which zircon-bearing sand was derived. These advances not only improve understanding of the western margin of North America during Cretaceous time, but also enhance the value of the Great Valley basin as an analog for other, less well preserved and documented ancient forearc basins.

April 28: Becky Lange, University of Michigan, Ann Arbor. Title: The origin of voluminous, highly differentiated rhyolites, the most evolved magmas on Earth, and the resolution of several paradoxes

May 5: No Colloquium, Final Exam Week