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THE JOURNAL OF GEOLOGY.

mistaken for the dip by the early workers in this region. A line drawn tangentially across the apices of the serratures shows the dip to be some 45° westerly in the upper (westerly) part. In this section the schist may be safely assumed to have a thickness of 800 feet. In some localities it is not over 50 feet thick, but just south of Chittenden village more than 1000 feet occur. All through the area the schist carries abundant lenses of secondary quartz introduced along the bedding and cleavage planes. These are considered genetically to be the excess of silica, resulting in great part from the decomposition of silicates originally in the rock, the alumina and potassium going to form the muscovite. Phases of the rock are without such lenses and are nearly free from quartz; other phases are largely quartz layers with thin folds of mica between. Some phases carry secondary feldspars, but they are exceptional. Under the microscope the normal constituents of the schist are seen to be a varying percentage of chlorite, a great deal of muscovite in slender, closely-packed plates and quartz in thin layers and scattered through the rock. Biotite in larger flakes is also universally present, with occasional feldspar grains.

Beneath the schist is the micaceous quartzite horizon, poorly represented in this section, but on Nickwacket Mountain having a thickness of 500 feet at least, and carrying several thin beds of crystalline limestone. Here there are not over 100 feet, with no interstratified limestone beds. It has scattered through it abundant pebbles of feldspar (microcline and orthoclase) besides quartz. The pebbles are small and have undoubted clastic outlines. Owing to their occurrence, this horizon is particularly easy to identify. Its strike is a little west of north, and the dip 80° easterly. Going east from the Olenellus quartzite the dips have grown continually steeper and now we find the rocks overturned to the west. This horizon presents many phases; traced south five miles it becomes a muscovitic schist, highly contorted, in which there is no evidence of detrital material; traced eastward towards the heart of the range, when caught in synclinal folds it is a granular, micaceous gneiss. Secondary feldspars

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