Geology of the 'Little Knife Edge', Baxter State Park, Maine

The 'Little Knife Edge' is a short portion of trail (~1/2 mile) on the Traveler Mountain Loop in Baxter State Park between the Peak of the Ridges summit and Traveler Mountain peak (Figure 1). The trail, named because its spectacular exposure is similar to the Knife Edge Trail near Baxter Peak, crosses the Black Cat Member of the Traveler Rhyolite. The rock is a highly compacted, welded ash-flow tuff containing ten percent small phenocrysts of plagioclase and pyroxene (Rankin and Caldwell, 2010). Structural features in this rock make for interesting terrain (Figure 2).

Figure 1

Figure 2

The Traveler Mountain Loop is a rugged 10.1 mile hike from the South Branch Pond Campground (Figure 3). Spectacular views from the mountain tops and ridges make this a worthwhile hike. Average hiking time for fit hikers is between 9 and 10 hours and the trail covers three mountain summits over 3000 feet: Peak of the Ridges (3254'), Traveler Mountain (3541') and North Traveler Mountain (3152'). It is recommended that hikers do the loop in a counterclockwise direction, going from the Center Ridge Trail to Traveler, over to North Traveler, and then down to South Branch Pond.

Figure 3

Figure 4

The entire loop trail is over the Black Cat Member of the Traveler Rhyolite. This deposit is named for outcrops on nearby Black Cat Mountain. The Black Cat Member overlies the slightly older Pogy Member of the Traveler Rhyolite (also an ash-flow tuff deposit). The Traveler Rhyolite is composed of a series of hot ash flows that are now stacked upon each other with the older Pogy Member on the bottom. The Black Cat Member is about 7000 feet thick and shows signs of being emplaced at a very high temperature. A number of the phenocrysts appear to have rolled or have end-to-end rotation indicating a down-slope movement after the welding and flattening of the pumice fragments (Figure 4).

Ash flows that make up the Traveler Rhyolite were deposited as nearly flat layers. These horizontal layers have been folded since emplacement by a variety of geologic processes. Also quite noticeable on the 'Little Knife Edge' are the columnar joints. They range in diameter from a few inches to a few feet and can be upwards of tens of yards long (Figure 5). Often a hexagonal shape is visible at the top end of the column like these from the summit of the Peak of the Ridges (Figure 6).

Figure 5

Figure 6

One of the most beautiful areas of Baxter State Park is found along the 'Little Knife Edge' on the Traveler Loop Trail (Figure 7). Spectacular views can really be enjoyed after some moderate hiking. This rugged environment is a great place to enjoy some of Maine's interesting flora (Figure 8), fauna and geology.

Figure 7

Figure 8

References

Nation, P. and Cummings, B., 2005, AMC Maine mountain guide (9th edition): Appalachian Mountain Club Books, Boston, 261 p.

Rankin, D.W., and Caldwell, D.W., 2010. A Guide to the Geology of Baxter State Park and Katahdin. Maine Geological Survey, Bulletin 43, 80 p., 2 maps.

Text and photos by Robert A. Johnston

Originally published on the web as the September 2010 Site of the Month.

Last updated on October 5, 2010