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found Ordovician fossils in the limestone belts some distance to the north and Cambrian fossils at Stissing Mountain to the southwest.

Lithological Character of Horizons.—(a) Canaan Dolomite. This bed seems to be very rich in magnesia, the rock being in some cases at least a true dolomite. This is shown by a number of analyses of it by Mr. J. S. Adam.^[1] This rock appears at the surface only in the extreme southeastern portion of the area here considered, where it presents few features different from those which are common to the Egremont Limestone. Farther to the eastward, however, and particularly in the vicinity of Canaan, it is often characterized by the presence of interesting metamorphic minerals, the well known salite and tremolite of that locality. Phlogopite also has in one or two instances been found. In its upper layers, where it approaches the overlying Riga Schist, the rock may become graphitic, as at Ore Hill. As it appears in the vicinity of the mountain, however, the rock presents no characters which can be relied upon to distinguish it from the higher Egremont Limestone, and the differentiation is based on stratigraphy alone.

(b) Riga Schist.—This horizon is tolerably uniform in character, the principal differences being in the presence and variable size of the metamorphic mineral individuals. Strictly speaking the rock is a gneiss, owing to the abundance of feldspar, but in order to distinguish it from more feldspathic and more or less granitoid gneisses lying east of the Housatonic River, it is best to refer to it as a schist, which it most resembles in structure. It almost invariably is porphyritic from the presence of lenticular to spherical grains of an acid plagioclase. The base is usually composed of feldspar, quartz, and a colorless mica (in part sericite) and biotite. Considerable graphite often exists in this base as does also ilmenite. Chlorite when present is usually in small amount. Garnets, staurolite, ottrelite, and biotite, as well as plagioclase, are developed at many localities. On the summit of the Lion's Head the rock contains garnets (rhombic dodeca-