ISGS Researchers Active at North-Central GSA

Thick (11 m) Peoria Silt loess near Owensboro being studied to correlate the paleosols (dark bands) with similar loess-paleosol sequences in southern Illinois. The loess shown was deposited between about 25,000 and 11,000 years ago during the Wisconsin Episode of glaciation.Four ISGS geologists co-led two field trips for the North-Central Geological Society of America (GSA)meeting in Evansville, Indiana. Thirty people from Maryland, Ohio, Pennsylvania, Nebraska, Missouri, Iowa, Indiana, and Kentucky attended the first trip, which covered the Illinois-Kentucky Fluorite District in southern Illinois and northwestern Kentucky. One of the trip highlights was the stop at the Hastie Mining Company quarry, the only place in Illinois where fluorite is currently mined as a by-product of the limestone quarry operation.

The second field trip, "From the Cincinnati Arch to the Illinois Basin, Geological Field Excursions along the Ohio River Valley", was organized by the Pander Society, a group of conodont enthusiasts organized in 1967. The society takes its name from the German scientist C.H. Pander, who in 1856 was the first to describe these enigmatic fossils. Conodonts are of great value in biostratigraphy, particularly in Silurian through Pennsylvanian age rocks. Conodonts undergo successive color changes with temperature of burial and can be used as an index to rank or maturation of hydrocarbon-bearing rock. The field trip visited four sites where conodonts are known to occur in Pennsylvanian rocks of southwestern Indiana. These sites were an outcrop of the Lead Creek Limestone, a surface coal mine showing Middle Pennsylvanian coal-bearing rocks, a box cut serving as the portal to an underground mine where Middle Pennsylvanian rocks are exposed, and the type outcrop of the West Franklin Limestone. The field trip was co-led by a retiree from the Indiana Geological Survey and a coal geologist who works as a consultant for Marshall Miller Co. in Evansville. For this trip, an ISGS geologist led the stop that discussed aspects of Pennsylvanian stratigraphy, sedimentation, and conodonts in southwestern Indiana. These two field trips were the only two trips at this year's North-Central GSA that were fully booked.

In addition to the field trips, ISGS staff members were co-authors of numerous abstracts presented at the meeting