Field Trips

1. High Resolution Stratigraphy of Lower and Middle Mississippian Strata of the Western Flank of the Ozark Plateau-Analogs for the Subsurface Mississippian Play of Kansas and Oklahoma.
Fri.-Sun., 14-16 March. US$450. Max: 50
2. Hydro Days! Karst Hydrogeology of the Southern Ozarks.
Sat.-Sun., 15-16 March. US$95. Max: 20
J. Van Brahana, University of Arkansas.
Continuing a long tradition, J. Van Brahana (professor emeritus, University of Arkansas and USGS, retired) will lead a two-day field trip through the southern Ozarks to view spectacular occurrences of mantled karst terrain, epikarst exposed by fluvial erosion, and the many caverns and springs of the region.
3. Uppermost Mississippian Strata in the Ozarks — Recent Mapping of the Imo Interval in NW Arkansas.
Sat., 15 March. US$35. Max: 15
Richard Hutto, Arkansas Geological Survey; Erin Smart, Weatherford Laboratories; Angela Chandler, Arkansas Geological Survey.
This fieldtrip will examine the principal reference section of the Imo interval then look at recently mapped exposures. The Imo Formation was proposed by Mackenzie Gordon in 1964 for a sequence of shale with interbedded sandstone and conglomerate above the Pitkin Limestone and below the Prairie Grove Member of the Hale Formation. Gordon found that this unit contains unequivocal Mississippian-age fossils, but abandoned the name in the same publication it was proposed due to concurrent mapping by E. E. Glick. Glick included this unit in his Cane Hill Formation which spanned the Mississippian-Pennsylvanian boundary. The name Cane Hill Formation was officially adopted by the Geologic Names Committee of the USGS in 1964, and the name Imo Formation officially abandoned. Nonetheless, the name Imo has been and still is unofficially applied to this interval by the geologic community as seen in various publications, and the name Cane Hill Formation has subsequently dropped from use. In the years since this unit was proposed and abandoned, it has been the subject of sometimes heated debate over its viability as a lithostratigraphic unit, but very little was done to try to map it in the field on a regional basis until recently.
Geologic mapping at the 1:24,000 scale for the STATEMAP Program (2006-2013) has delineated the Imo interval on thirteen (13) 7.5 minute quadrangles in north-central Arkansas. Lithologically, the unit consists of interbedded sequences of locally fossiliferous shale, sandstone, sandy fossiliferous limestone and conglomerate. To date, the Imo has been mapped in three (3) counties totaling roughly 84 square miles of outcrop area.
4. Middle and Late Morrowan Depositional History and Sequences, NW Arkansas.
Sun., 16 March. US$50. Max: 15
Angela Chandler, Arkansas Geological Survey; Doy Zachry, University of Arkansas; Walter Manger, University of Arkansas emeritus.
The Morrowan Field Trip will involve an east to west traverse along structural and depositional strike from Parthenon, Arkansas in Newton County to Fayetteville in Washington County. The stops along highways 74, 23 and 512 will emphasize facies changes along strike from positions proximal to an eastern terrigenous source to successions with increasing amounts of carbonate sediment. Marine and non- marine environments are represented. Fluvial, tidally-dominated, open marine and storm- dominated shelf facies will be emphasized. The units that contain them are placed in a sequence stratigraphic framework.
5. Slaughter in the Rocks and Other Geological Aspects of the Battle of Pea Ridge.
Sun., 16 March. US$85. Max: 8
6. Quaternary Geology and Geomorphology of the Buffalo National Scenic River.
Wed., 19 March. US$75 Professional/$55 Student. Max: 30
Stephanie Shepherd, Bloomsburg University; Amanda Keen-Zebert, Desert Research Institute; Mark Hudson, USGS.

The Buffalo National Scenic River is the nation’s first and foremost national river. Sequences of strath terraces and perched caves in the catchment may represent past periods of transience and episodic incision in the catchment, and stratified alluvial sediments overlying the straths and contained in subterranean caves archive the incision history of the river. We will discuss the driving mechanisms and Quaternary rates of river incision on the Buffalo River derived from recent geochronologic work, the role of lithology in filtering base level fall across catchments with very low uplift rates, ongoing mapping efforts by the USGS, and management issues related to karst and the geomorphology of the watershed.


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