GLACIAL OUTFLOW ORIGIN OF MASSIE CREEK GORGE, GREENE COUNTY OHIO

Massie Creek Gorge is one of several small but impressive canyons in Greene County, Ohio that are cut through a typically low-relief landscape. Massie Creek Gorge displays spectacular dolomite cliffs (up to 20 m high), large rockfalls (averaging 100 m³ in the lower gorge and 1800 m³ in the upper gorge), numerous large potholes (up to >5 m wide and >7 m high), a dry valley branching off the main channel with a resultant bedrock island (~18,000 m² in area) and two boulder bars on its lee side (the largest ~13.5 m thick). Short side canyons are cut to the same depth as the main drainage, but are dry; sometimes they also contain potholes on their walls. Massie Creek Gorge’s geomorphological features, its location in relation to end moraines from the last glacial episode, and regional surficial deposits and stratigraphy indicate the terminus of the glacial ice was directly above the proximal end of Massie Creek Gorge. With the exception of some late-occurring rockfalls, sediment deposition, aggrading spring deposits and the undersized river show Massie Creek Gorge is a relict landscape. Joint orientations correlate locally with gorge direction and perpendicular side-streams/crevices, and regionally with morphologically similar Clifton Gorge and Glen Helen Gorges. Previous studies concerning these two nearby gorges were analyzed, along with work dealing with glacial history, processes, and features in southwestern Ohio.

Studies dealing with pothole types and formation were reviewed and applied to Massie Creek Gorge. These along with the dry river channel, the bedrock island, boulder bars and short but deep side canyons testify to very significant past flow conditions. Evidence suggests the gorge was cut by high-volume, sediment-laden outwash from ice that was in close proximity to the gorge, probably during a glacial outburst flood or rapid glacial melting and retreat. This is consistent with the scale of potholes and boulder bars found within the canyon. The origin of this gorge may provide clues concerning the origin of other gorges around southwestern Ohio and deep canyons near significant end moraines.