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Bedrock of the Saxtons River 7.5'x15' minute quadrangle ranges in age from Middle Proterozoic to Cretaceous. All of the rocks, except for the late granitic and mafic dikes, are weakly to very strongly deformed, high-grade metamorphic rocks, such as schists and gneisses. The major geologic feature is the domal exposure of Middle Proterozoic gneiss and granite that makes up the core of the Chester and Athens domes in the eastern one third of the map. The narrowed connection, a structural saddle between the domes, forms the juncture between the generally south-plunging end of the Chester dome to the north and the north-plunging Athens dome to the south. From west of the domes to the border of the quadrangle is a broad belt of structurally very complex cover rocks that range in age from Late Proterozoic to perhaps uppermost Ordovician. A conspicuous structure in this belt is the Spring Hill syncline which has rocks of the Cram Hill Formation in its core. To the west, Middle Proterozoic gneisses appear in the core of the Butternut Hill fold. Near the northwestern corner of the map, Middle Proterozoic basement rocks that correlate with the core rocks of the Chester and Athens domes reappear to form the eastern margin of the Green Mountain massif. East of the Chester and Athens domes, a moderately steeply east-dipping sequence of Late Proterozoic to Early Devonian cover rocks is exposed. This eastern cover sequence generally correlates with similar cover rocks in the western part of the quadrangle. Subtle and perhaps very significant differences in rock types and stratigraphic relations of these two sections may exist. Although the general map pattern and stratigraphic relations of the cover rocks appear simple, their internal structure and relation to underlying basement rocks is quite complex. Quite possibly there is much more extensive faulting and intricate folding in the cover sequence rocks than is shown on the map. Previous and generally accepted interpretations of the geology (Doll and others, 1961) portrayed large refolded Middle Devonian nappes (Acadian) that involved basement and cover rocks (see cross section A-A' on figure 1). The southern terminus of the Middle Proterozoic rocks in the core of the Butternut Hill fold, for example, was interpreted as a north-plunging inverted sequence of rocks in a recumbent west-facing nappe that roots in the core of the Chester dome to the north. The Spring Hill syncline was also mapped as a north-plunging structure at both

Bedrock geologic map of the Saxtons River 7.5' x 15' quadrangle, Windham and Windsor counties, Vermont