Some Geological Features at Moxie Falls
|With a single vertical drop of nearly 90 feet, Moxie Falls (Figure 1) in Moxie Gore near The Forks, is one of Maine's highest waterfalls and a spectacular sight in any season. Several smaller falls and plunge pools make this section of Moxie Stream a scenic location well worth the short hike from the public parking area along Moxie Pond Road (Figure 2). For the more adventurous, the falls are a short hike upstream from exhilarating rafting on the Kennebec River. The land including Moxie Falls is maintained for public enjoyment by the Maine Department of Conservation, Bureau of Parks and Lands.|
General geology of the Moxie Falls area
|Mineral exploration and an opportunity to unravel interesting geological events were the main factors behind the drive to map the geology of the area during the 1960s and 1970s by the U.S. Geological Survey, the Maine Geological Survey, and various private mining companies. Figure 3 is a generalized bedrock geologic map of The Forks quadrangle which includes the boundary, interpreted as an angular unconformity, between older rocks of Cambrian and Ordovician age, and younger rocks of Silurian and Devonian age (See the USGS Geologic Time Scale). The primary unit exposed at Moxie Falls is The Forks Formation of Silurian age. Rocks of the formation are exposed in a broad anticline which causes a unit of Devonian gray slate to be repeated on the west and east sides of the outcrop belt of The Forks Formation.|
The Forks Formation
A number of closely related sedimentary and metamorphic rock types comprise The Forks Formation. These include thinly bedded silty limestone, calcareous (limy) siltstone, sandstone, and phyllites. The limier beds often contain abundant fossilized fragments of crinoids, which help establish the Silurian age of the unit. In this area of Maine, metamorphism is fairly weak such that many of the primary sedimentary features are still preserved in the rocks. A few thin granitic dikes intrude The Forks Formation at the falls and elsewhere along Moxie Stream.
Burroughs, W.A., and Marvinney, R.G., 1981, Reconnaissance bedrock geology of The Forks quadrangle, Maine: Maine Geological Survey, Open-File Map 81-10, scale 1:62,500.
Marvinney, R.G., 1984, The Forks Formation of northwestern Maine: evidence for a Late Ordovician to Late Silurian angular unconformity: Northeastern Geology, v. 6, p. 151-160.
Text and photos by R. Marvinney.
Last updated on March 6, 2008