The Waits River formation represents a series of sediments which accumulated at the bottom of a shallow sea during Ordovician time. These sediments included both limy and sandy beds, and fossils may originally have been preserved in some of the beds. Sediments of other types later accumulated over the Waits River formation during a long period of geologic time, so that eventually the formation became deeply buried. (See Figure 3.) The sea retreated and the rocks were subjected to high pressure and temperatures during a period of mountain-building. The rocks which had been sedimentary were folded and converted to _metamorphic rocks_ by partial melting and recrystallization of the components. As a result the rocks became schists or marbles. Any fossils which may have been present were destroyed or badly altered in the process. This is unfortunate because valuable geologic information as the age of the rocks can be determined from the type of fossils present. 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.