Location This double site is in western Maine, about 5 hours drive north from Boston. Figure 1 shows the geology of the area and 16 numbered stops along and near Maine 4 between Oquossoc and Phillips. Most of the area is covered by geologic maps of the Kennebago Lake Quadrangle (Boudette, 1986) and the Phillips and Rangeley quadrangles (Moench, 1971); and a regional synthesis is provided by Moench and Pankiwskyj (1986). Rangeley village is the most convenient base for large groups. Directions to the numbered stops follow. Stop 1. Large outcrop of Dead River Formation on the shore of Mooselookmeguntic Lake at the north end of the causeway to Spots Island. Obtain permission from residents on the island. Because the parking area at the causeway is limited, large groups should park in Oquossoc and walk (about 0.3 or 0.4 mi; 0.5 or 0.6 km). Stop 2. Low road cut in black slate on the north side of Maine 4,0.7 mi ( 1.1 km) east of its intersection with Maine 16 near Oquossoc. Stop 3. Large road cut of Graywacke Member of Quimby Formation on Maine 4 near Dodge Pond, 3 mi (4.8 km) east of its intersection with Maine 16.

Ages from 17 new graptolite localities have made possible refinements in Silurian and Silurian-Devonian stratigraphy in the Kingsbury and Skowhegan quadrangles and indicate major facies changes in the Silurian metasedimentary rocks of central Maine. Northwest of the Currier Hill syncline, the observed sequence is: Sangerville Formation (upper Llandovery through lower Wenlock)—variably bedded meta-graywacke and pelite with minor polymict granule conglomerate, ribbon limestone, and carbonaceous pelite; Eddy Formation (lower Ludlow)—rusty weathering sulfidic carbonaceous pelite and non-carbonaceous quartzose sandstone and granule conglomerate; Brighton Formation [Silurian-Devonian(?)]—massive biotite-quartz granulite with minor calc-silicate granulite beds and pods (lower member) and thinly interbedded biotite-quartz granulite and biotite-muscovite phyllite (upper member); Solon Formation [Lower Devonian(?)]—nearly homogeneous slate with occasional rhythmically interbedded quartzose sandstone and slate. Southeast of the Currier Hill syncline, the sequence is similar but there is a decrease in grain size in most units accompanied by an increased amount of pelite and a drastic thinning of Sangerville bedding to produce a pinstriped unit (transitional Sangerville). My interpretation of the facies relationships suggests a sequence that becomes finer to the east with a source of sediments to the northwest. Correlations based on projection of these facies changes and on fossil ages wherever possible yield the following: West Seboomook Formation Madrid Formation Smalls Falls Formation Perry Mountain Formation Rangeley Formation Solon Formation Brighton Formation Eddy Formation Sangerville Formation East Vassalboro Formation Waterville Formation Mayflower Hill Formation