186-4 Comparing historic plant fossil collections from Rush Creek at the Working Men’s Institute to specimens collected from the Bond Formation (Upper Pennsylvanian, Missourian) at the Old Dam Site, New Harmony, Posey County, Indiana

Session: New Approaches to Old Fossil Collections (Posters)

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Abstract:

The Working Men’s Institute (WMI) of New Harmony is a historical institution founded in 1838 by William Maclure (1763–1840), Father of North American geology, which serves as a public library, archive, and museum. The WMI collections include over 35,000 natural history specimens or lots, of which there are over 1,100 plant fossils. In the late 1830s through the 1870s, New Harmony residents Edward Travers Cox (1821–1907) and James Sampson (1806–1890) gathered, identified, and preserved fossils and other natural history specimens, for which portions of their collections remain at the WMI, with some on display in the museum. Relevant to this study are plant fossil specimens from two historic sites in the Bond Formation: Harmony Cut-off and Rush Creek. The Bond Formation (Upper Pennsylvanian, Missourian) of the McLeansboro Group includes shale, siltstone, and sandstone, with subordinate layers of coal and limestone. A partial exposure of the Bond Formation is accessible along the Wabash River southwest of New Harmony at the Old Dam Site. Plant fossils were collected in late August 2024 from a dark gray, unnamed shale just below a thin coal deposit. The most common fossils are Medullosans, dominated by Neuropteris. Multiple individual pinnules of Macroneuropteris scheuchzeri occur in samples dominated by N. flexuosa, N. ovata, and N. vermicularis. There is a moderate abundance of Calamites, Cordaites, and Cyclopteris, along with Annularia sphenophylloides and N. fimbriata. There are trace occurrences of Sphenophyllum dubium, Sphenophyllum emarginatum, and Sphenopteris elegans. The same genera-species dominate over 400 specimens that are attributed to the Harmony Cut-off and Rush Creek localities in the WMI collections. The plant fossil genera identified from the Bond Formation are typical of the Late Pennsylvanian and indicate a paleoclimate with marginally drier conditions than the Early Pennsylvanian. The abundance of dry-adapted flora suggests an environment that is seasonally, or on average, much drier in comparison to the tree-fern and lycopsid-rich swamps of the Lower Pennsylvanian.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9348

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