The rocks of the Waits River formation at Ricker Mills are dominantly mica schists with layers containing limy material. These are too impure to be considered marble but enough lime is present so that they react strongly with acid, a test for detecting the presence of lime. The schists principally contain quartz, biotite, calcite (lime) with lesser amounts of muscovite, feldspar and impurities. The rocks weather to dark colors; the gray limy beds are particularly susceptible to weathering and turn dark brown to black on the surface. When more lime is present, the rock weathers to a deep brown porous rock which resembles decayed wood. Some boulders of these altered limestones are found in the glacial deposits in the State Forest.
An additional factor which makes the rocks in the railroad cut at Ricker Mills look “messy” is the iron and manganese staining and the formation of mineral crusts on the surface of the rocks through the action of ground water. Rain water falling on the hills above passes through the soils, dissolving minerals, and precipitating them where the water seeps out and evaporates at the lower level of the railroad tracks.
The schists trend about N.80°W. and dip about 30° to the northeast. Along the length of the rock exposures it can be seen that this dip is not constant but varies from 10 to 30°. The variation in dip gives the schists a wavy appearance.
At two places along the railroad cut, the schist has been intruded by granite. As is shown in [Figure 6], which is a sketch of the rocks exposed on the east side of the railroad, the granite forms vertical dikes. As the schist ends abruptly at the contact of the granite, this indicates that the granite formed after the schist. The granite is nearly the same as the granite in Groton State Forest except that the mica is muscovite rather than biotite. For this reason the granite is lighter in color on fresh surfaces. In general the exterior is dark in color due to the staining of iron from weathering of the mineral pyrite, an iron sulfide, which occurs in small amounts in the granite.
Jerry Lund Mountain
On top of Jerry Lund Mountain occur other outcrops of the Waits River formation and granite. Their exact relationships cannot be seen easily because of the thick vegetation. The Waits River formation on Jerry Lund Mountain is composed principally of quartz mica schist.
TRIPS TO TAKE
Hiking in the State Forest
The hike from the end of the road to the top of Owlshead Mountain takes only ten to fifteen minutes. A splendid view of the surrounding area, particularly Groton and Kettle ponds, is obtained from here. If possible, everyone who visits the park should take this short walk. The granite is well-exposed at the summit and dikes of aplite and pegmatite may be seen.
The more venturesome park visitor will want to make other trips away from the “beaten path” into the wilderness of the Vermont woods. The principal difficulty arises in that the wilderness is so real a person may well become lost if he strays too far from the trails. Some of the trails have become overgrown so that they are difficult to follow and portions of others have been destroyed by the damming up of brooks by the beavers. It is suggested that in planning hikes information be obtained from the park superintendent about the condition of the various trails.