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Home > Explore! > Bedrock Geology > Field Localities > Gordon Falls

Gordon Falls on the Mattawamkeag River:
Red Rocks and White Water

upper gordon falls
Upper Gordon Falls, Mattawamkeag River, Maine

topographic location map
Figure 1		 Upper and Lower Gordon Falls on the Mattawamkeag River (Figure 1) in the towns of Mattawamkeag and Winn are an excellent locality to view several stretches of Maine whitewater rapids, examine water-worn potholes in the bedrock, scramble over structurally complex Silurian metasediments, and even get a lesson in the transport of glacial erratics .... and, at the right time of the year, take a dip in the Mattawamkeag River.
mattawamkeag river sign

Location and directions:

  • Take Interstate 95 north from Bangor to Lincoln.
  • From Lincoln, take Route 2 north to the town of Mattawamkeag.
  • Look for the sign on the right leading to the Mattawamkeag Wilderness Park (Figure 2).
  • Turn right here and check your odometer.
  • Follow the road toward the Wilderness Park; at 3.4 miles from Route 2, watch for and cautiously cross the bridge (Figure 3) over Mattakeunk Stream.
mattawamkeag wilderness park
Figure 2		 bridge over Mattakeunk Stream
Figure 3
  • Continue to Lower Gordon Falls at 4.9 miles.
  • Upper Gordon Falls is 0.1 mile further up the road - easy walking distance from the Lower Falls.
lower gorden falls sign        upper gordon falls sign

The Mattawamkeag River is the longest river in Maine with effectively no regulation of its flow by dams. The river drains slightly over 1500 square miles, and the large basin size and high percentage of wetlands in the basin provides moderate flows even throughout the summer months. The U.S. Geological Survey maintains a stream gage just below Lower Gordon Falls.

stream flow from October 2005 through August 2006
Figure 4		 The hydrograph (Figure 4) shows that a very wet fall in 2005 and warm and wet winter in 2006 kept stream flows well above the median values until April of 2006, when a dry spring and minimal snowpack produced a lower than normal freshet. The flows when the high-water and low-water photographs below were taken are indicated on the figure.

By statute, the Mattawamkeag River from the Kingman-Mattawamkeag boundary to its confluence with the Penobscot River is defined as a Class AA river, the highest water quality classification for a river in Maine [MSRS Title 38, sec. 467, 7,D,(1),(b)]. (See the Maine Department of Environmental Protection's Classification of Maine Waters for a description of Maine's water quality classifications.)

The stretch of the Mattawamkeag River from Kingman to Mattawamkeag is rated as Class II-IV for canoeists and kayakers. The most difficult stretch is through Slewgundy Heater upstream from Gordon Falls. This stretch of river through Slewgundy Heater is not as accessible as Gordon Falls, however, and does not provide as much access to the rocks. Descriptions of runs through this section of the river can be read at the American Whitewater Mattawamkeag webpage.

These photo pairs taken from approximately the same location show the Falls in April during high-water conditions and in early August during low-water conditions:

Lower Gordon FallsUpper Gordon Falls
high and low water at Lower Gordon Falls
Figure 5		 high and low water at Upper Gordon Falls
Figure 6

The Mattawamkeag drainage basin is underlain primarily by Ordovician and Silurian metamorphosed sedimentary rocks of the Kearsarge-Central Maine synclinorium. On the 1985 Bedrock Geologic Map of Maine (Osberg and others, 1985), the rocks at Gordon Falls are described as "Silurian undifferentiated pelites and sandstones," but subsequent work suggests a correlation with the Silurian Smyrna Mills Formation to the north (Hopeck, 1991; Ludman and others, 1993). The metamorphic grade is low - greenschist grade and lower - and the combination of the pelitic nature of the rock and low metamorphic grade explains the low topographic relief and high percentage of wetlands in the basin.

The bulk of the exposed bedrock at Gordon Falls are green to gray pelites with a pronounced slaty cleavage (Figure 7). However, at low water, benches of bedrock at the lower end of Upper Gordon Falls reveal reddish beds (Figure 8) much richer in iron and manganese than the bulk of the formation. To the north, manganese deposits in the Silurian Maple Mountain Formation (Pavlides, 1962) (correlated with Smyrna Mills Formation and the undifferentiated pelitic rocks at Gordon Falls) may have been deposited in a similar sedimentary environment.

pelitic rocks with slaty cleavage
Figure 7		 iron-rich pelitic rocks
Figure 8		 river parallel to foliation
Figure 9		 river crosses foliation
Figure 10

The rocks are strongly foliated in a N35E direction with near vertical dips. This foliation is sub-parallel to the primary bedding in the rock. At Lower Gordon Falls, the river is parallel to the foliation and bedding (Figure 9). At Upper Gordon Falls, the river runs across the strike of the foliation (Figure 10).

The 90-degree bend in the river at Gordon Falls is most likely due to the river following a late, northwest trending fracture orientation. Abundant quartz veins, shearing, and truncated foliation and compositional layering at Upper Gordon Falls support this idea.

At Lower Gordon Falls, the orientation of the foliation parallel to the river is very favorable to the formation of potholes in the bedrock, caused by erosion produced by sediment trapped in eddies abrading the bedrock. Potholes (Figure 11) are common at low water at Lower Gordon Falls, but absent at Upper Gordon Falls.

potholes at Lower Gordon Falls
Figure 11		 stair-step effect at Upper Gordon Falls
Figure 12		 geologist studying structure
Figure 13		 folding at Upper Gordon Falls
Figure 14		 Z-folds at Upper Gordon Falls
Figure 15

Upper Gordon Falls is more difficult for canoeists and kayakers to navigate because the river steps down across the bedrock ledges (Figure 12). At Upper Gordon Falls, the orientation of foliation at right angles to the river provides much more bedrock exposure (Figure 13). The broader benches exposed at Upper Gordon Falls show some of the complex folding present in the rock (Figure 14 and Figure 15).

glacial erratic
Figure 16		 As you walk around the falls, look at the many loose boulders ranging in size from basketballs to small cars. You should notice that there are very few boulders of the local bedrock - it is far too foliated and weak to take much transport and the associated grinding by glacial ice. In fact, the vast majority of boulders are Katahdin granite (Figure 16). The Katahdin batholith, the source for most of the boulders, is about 30 miles northwest of the Falls.

References

Hopeck, John T., 1991, Faulting and related fabrics in the Miramichi and Aroostook - Matapedia tracts, Maine, in Ludman, Allan (editor), Geology of the coastal lithotectonic block and neighboring terranes, eastern Maine and southern New Brunswick: New England Intercollegiate Geological Conference, 83rd Annual Meeting, September 27-29, 1991, Princeton, Maine, p. 294-308.

Ludman, Allan, Hopeck, John T., and Brock, Pamela Chase, 1993, Nature of the Acadian orogeny in eastern Maine, in Roy, David C., and Skehan, James W. (editors), The Acadian orogeny; recent studies in New England, Maritime Canada, and the autochthonous foreland: Geological Society of America, Special Paper 275, p. 67-84.

Osberg, Phillip H., Hussey, Arthur M., II and Boone, Gary (editors), 1985, Bedrock geologic map of Maine: Maine Geological Survey (Department of Conservation), scale 1:500,000.

Pavlides, Louis, 1962, Geology and manganese deposits of the Maple and Hovey Mountains area, Aroostook County, Maine: U. S. Geological Survey, Professional Paper 362, 116 p.

Text and photos by M. Loiselle.

Originally published on the web as the September 2006 Site of the Month.

Last updated on April 12, 2012