The Geology of the Moose River "Bow Trip" – Northwestern Maine

Introduction

The Moose River lies in the Kennebec River watershed and flows east from its beginnings in the mountains along the Maine and Canadian border (Figure 1). The river flows into Long and Brassua Lakes and eventually to Moosehead Lake and the headwaters of the Kennebec River. A twenty-four mile section of the Moose River is a portion of the "Bow Trip," a popular three-season canoe trip (Figure 2). The Bow Trip travels through remote forests and bogs and across isolated Attean and Holeb Ponds. The entire trip is 34 miles long and is usually done in three days. The canoe trip can begin at the east end of Attean Pond off Maine Route 201 or at Holeb Landing, by way of Holeb Road. There are three or four recommended portages, including a one and a quarter mile portage between Attean and Holeb Ponds.

Figure 1

Figure 2

The geology of the Moose River is dominated by two factors, the underlying resistant bedrock (Attean Quartz Monzonite) and the lingering effects of continental glaciation. The "Bow Trip" section of the Moose River is mostly flat water with occasional whitewater areas where bedrock outcrops occur. Continental glaciation of late-Wisconsinan age scoured out lake basins and river valleys, and smoothed bedrock outcrops. Glacial ice filled valley lowlands, dammed meltwaters, and created large proglacial lakes. Thick layers of silt and clay were deposited in these lakes and are now being reworked by the modern river.

Regional Geology

The Moose River is underlain by Ordovician-age igneous and metamorphic rocks. The Attean Quartz Monzonite is the most common rock type along the river and ponds with diorite, a plutonic rock, the second most common rock type. Outcroppings of granofels, a metamorphic rock, are also encountered (Figure 3 and Figure 4).

The region lies on the crest of a major structural feature, the Boundary Mountain anticlinorium (Albee and Boudette, 1972) which extends from northern New Hampshire into northwestern Maine. This extensive feature is composed of many smaller folds, which themselves are on the order of several miles across. The region is well covered by glacial materials, most commonly till (also called diamicton), an unsorted and unstratified sediment which was deposited directly in contact with glacial ice (Figure 5 and Figure 6).

Moose River Geology

We begin the canoe trip at Holeb Landing, on the northwest shore of Holeb Pond where there is a popular Maine Forest Service campsite. Outcrops here and on Birch Island, a half-mile offshore from the Landing, are granofels and diorite. Granofels is a medium- to coarse-grained metamorphic rock which has little or no foliation or lineation. Diorite exposed here is a dark-colored, fine- to medium-grained hornblende diorite. Along the shoreline of Holeb Pond are deposits of broken rocks, consisting of granofels, diorite, and Attean Quartz Monzonite which have been broken up by wave, ice and frost action (Figure 7). Holeb Stream, which leads to the Moose River, is about a one mile paddle to the southwest from Holeb Landing. At times of high water, Holeb Stream flows into Holeb Pond. Flooding in the Moose River causes water and sediment to reverse flow and over time the lake-outlet delta found at the west end of Holeb Pond formed (see Caldwell and others, 1989). Shortly after entering Holeb Stream, one paddles under the Canadian-Pacific rail line. Fill brought in here to support the tracks is most likely slate from the Brownville Junction area, almost one hundred miles to the east by rail.

Figure 7

Figure 8

A mile down Holeb Stream is the confluence of the Moose River (Figure 8). From here the Moose River meanders southeast for about two miles along the eastern edge of a large esker, a long, narrow ridge of stratified sand and gravel which was deposited in a subglacial tunnel. Geophysical surveys show this esker to contain a thickness of over fifty feet of sand and gravel. Coarse boulder gravels often are exposed along the riverbank, in sharp contrast to the more commonly seen fine sand, silt, and clay.

Outcrops of Attean Quartz Monzonite (Figure 9) are encountered at Camel Rips (Figure 10), Holeb Falls, Mosquito Rips, Spencer Rips, and Attean Falls. With basic canoeing skills, four of these rapids can be run in medium to high water. However, Holeb Falls can never be run as it is a forty-foot drop down a steep chasm (Figure 11). The portage trail around Holeb Falls is along the north side of the river.

In areas where the river meanders, thick deposits of fine-grained silts and clays are found (Figure 12), evidence that in the distant past lakes existed along these stretches. Number 5 Bog, one of Maine's largest peat deposits at over 1,400 acres, lies just north of the Moose River, in T4 R7, T5 R7, and Attean Townships. Fifteen to twenty feet of peat has been identified in the bog, again providing evidence of an old lake filling the basin (Cameron and others, 1984). Number 5 Bog is nationally recognized for its rare plants and associated jack pine tree stand (Tyler and Davis, 1982). Smaller bogs are found along other stretches of the Moose River.

Attean and Holeb Ponds

Once past Attean Falls (Figure 13) paddling is across remote Attean Pond (and Holeb Pond if the trip was started there). Boulders and outcrops found in and along the shore of Attean and Holeb Ponds are Attean Quartz Monzonite. Once out on Attean or Holeb Ponds, one can look up at Attean Mountain to see the effects of glaciation with its smooth northern side and a steeper, plucked southern side. Similar shaping of bedrock is seen on many of the small islands in Attean and Holeb Ponds, an indicator of the northwest to southeast flow of the ice (Figure 14). Beautiful sand beaches (Figure 15) are also found on the two ponds. The mile and a quarter portage between Attean and Holeb Ponds (Figure 16) is mostly on till and small wetland units, but outcrops of the monzonite are also encountered. Till lies mostly on the upland areas while silt and clay cover the lowland areas. Once back on Holeb Pond, paddling towards our starting point at Holeb Landing, a lens of granofels is encountered (Figure 17), between outcrops of the Attean Quartz Monzonite.

The Moose River trip is not one of Maine's big whitewater canoe trips, but it does offer peaceful paddling through a beautiful region. The ability to start and finish at the same spot and not shuttle vehicles, as well as the remote beauty of the area, make this a very popular trip during the summer season.

References

Albee, A. L., Boudette, E. L., 1972, Geology of the Attean quadrangle, Somerset County, Maine: U.S. Geological Survey, Bulletin 1297, 110 p., 2 maps.

Appalachian Mountain Club, 2002, AMC River Guide, 3rd Edition, Maine: Appalachian Mountain Club, Boston, Massachusetts, 347 p.

Caldwell, D. W., Fitzgerald, D. M. and Fenster, M. S., 1989, Origin and sedimentation of Maine lakes with emphasis on lake-outlet deltas; in Tucker, R. D. and Marvinney, R. G. (editors), Studies in Maine geology, Volume 5: Quaternary geology: Maine Geological Survey, p. 97-108.

Cameron, C. C., Mullen, M. K., Lepage, C. A. and Anderson, W. A., 1984, Peat resources of Maine, Volume 3: Piscataquis and Somerset Counties: Maine Geological Survey, Bulletin 30, 127 p.

Delorme, 2006, Maine Atlas and Gazetteer: Delorme, Yarmouth, Maine, 18 p., 78 maps.

Thomas, E., 1973, No horns blowing, canoeing 10 great rivers in Maine: Hallowell Printing Company, Hallowell, Maine, 134 p.

Tyler, H. R., Jr., and Davis, C. V., 1982, Evaluation of No. 5 Bog and jack pine stand, Somerset County, Maine, as a potential National Natural Landmark: Maine Critical Areas Program, State Planning Office, 41 p.

Text and photos by Robert A. Johnston.

Originally published on the web as the October 2007 Site of the Month.

Last updated on October 1, 2007