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297-2 Clastic Sediments from Sarah Furnace Cave, Pennsylvania, Record Hydrologic and Landscape Evolution of the Appalachian Plateau

Session: Caves and Karst Through Space and Time: Biogeochemistry, Climate, and Astrobiology (Posters)

Poster Booth No.: 91

Presenting Author:

Ryan Johnston

Authors:

Johnston, Ryan J.¹, Sasowsky, Ira D.², Feinberg, Joshua M.³, Ashbrook, Bert⁴

(1) Department of Geosciences, The University of Akron, Akron, OH, USA, (2) Department of Geosciences, University of Akron, Akron, OH, USA, (3) University of Minnesota, Minneapolis, MN, USA, (4) Mid-Atlantic Karst Conservancy, Blairsville, PA, USA,

Abstract:

Sarah Furnace Cave, Clarion County, Pennsylvania, is a 16 km-long, horizontal, dense maze formed in the Vanport Limestone. The cave position in the wall of the Allegheny River valley, 90 m above present river levels, implies significant antiquity. Cave passages measure up to 1-m tall and are underlain with almost 2 m of clastic sediment. Sediment and cave elevation consistent with peak heights of glacial paleolake Monongahela (lake age circa 1100-457 ka) suggest a potential genetic relationship. We examined the sediments to clarify origin of deposition, time frame of both sediment deposition and cave formation, and the paleoenvironment present during this time. The goal is to elucidate the landscape and hydrologic evolution of this portion of the Appalachian plateau.

Portions of the sediment surface are desiccation-cracked and show evidence of desiccation compaction. Bulk and core sediments were collected from five locations in the cave. Cores were driven 58 to 125 cm, but recoveries were 25 to 55 cm due to compression or internal friction. Analytical techniques, including LOI, XRD, and XRF, along with sedimentary structures and granulometry, were used to characterize the deposits. Magnetic experiments were conducted to determine polarity and magnetic mineralogy. We collected hysteresis loops and backfield curves, identified Verwey transitions, and measured anisotropy of magnetic susceptibility of the sediments to accomplish this.

Sediments are mostly composed of clays and fine silts, and slightly fine with distance from the valley wall. Sand percentage mostly varies from 3% to 25%. All samples showed normal polarity, with shallowing of inclination from expected present-day field. Goethite and maghemite were the primary magnetic minerals within the sediment, and the magnetic properties of the cave sediment differ from those found within the Vanport Limestone and overlying Buhrstone iron ore. Therefore, the sediment within the cave did not originate from the cave host rock and is instead allogenic. Potential sources of sediment are from the incising Allegheny River before glacial Lake Monongahela or during seasonal lake level fluctuations. It is unclear whether the waters responsible for cave formation are the same as those that deposited the sediments.

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

doi: 10.1130/abs/2025AM-7596

Clastic Sediments from Sarah Furnace Cave, Pennsylvania, Record Hydrologic and Landscape Evolution of the Appalachian Plateau

Description

Session Format: Poster

Presentation Date: 10/22/2025

Presentation Room: HBGCC, Hall 1

Poster Booth No.: 91

Author Availability: 3:30–5:30 p.m.

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