784 THE JOURNAL OF GEOLOGY. 



the writer accord with those of Professor Dana in the second 

 instance only, which relates to the upper or Everett schist mem- 

 ber. As will be fully shown below, the other mentioned locali- 

 ties have a much more complicated structure than was supposed 

 by Professor Dana. 



LITHOLOGICAL CHARACTERS OF THE HORIZONS. 



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 com- 

 mon 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 dimen- 

 sions 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 



1 These minerals were described from this locality in 1824 by Dr. Chester Dewey. 

 Am. Journ. Sci., Vol. VIIL, p. 7. 



2 Professor Dana has specially mentioned them from many of these localities. 

 (1. c, p. 440). The increase in size of garnets and staurolite from Mt. Washington to 

 the Housatonic, as described by him, has not been confirmed by this study. The 

 largest that have been noted are from the south end of the ridge south of Chapinville 

 Station. 



