Page:The Journal of geology (IA journalofgeology11893univers).pdf/362

the writer accord with those of Professor Dana in the second instance only, which relates to the upper or Everett schist member. As will be fully shown below, the other mentioned localities have a much more complicated structure than was supposed by Professor Dana.

As has already been stated, the horizons outcropping within this area all belong to the Mt. Washington series, viz.: The Canaan Dolomite, the Riga Schist, the Egremont Limestone, and the Everett Schist. The Canaan Dolmite seems to be for the most part a dolomite or dolomitic limestone, with more or less admixed quartz. A white pyroxene or salite is found to be common in it in the vicinity of Canaan, and in the belts extending east and northeast from that point. It has also been found at several localities in the vicinity of Lime Rock, but is only rarely seen west and southwest of that place. Tremolite is also found in this horizon, but as will be more fully explained beyond, this is largely restricted to a zone bordering the Housatonic River on the east. Masses of Canaanite are also found in this horizon, and as neither pyroxene nor tremolite has been found in the Egremont Limestone, their presence here is useful for purposes of identification.

The Riga Schist within this area has the characters which distinguish it on Mount Washington. In most of the ridges where it occurs, garnets alone or garnets and staurolites have been found in it. They are most abundant and of largest dimensions in the ridge south of Twin Lakes Station, the ridge south of Chapinville Station, in Tom's Hill and Mile's Hill, in Mt. Prospect (south of the area here mapped), and in Barnard Mt. and Johnny's Mt.^[1] near Sheffield.^[2] The mica is often a silvery