NOVACULITE SCHIST. 511 



be called talc were it not too hard. We use the term novaculite schist to embrace all the pure and impure 

 varieties of novaculite in Vermont. They are not confined to the formation now under consideration, but 

 are connected with all the ranges of clay slate. 



The novaculite schist connected with the talcose schist is mostly confined to one or two narrow belts in 

 the east part of the middle range, between Northfield and Memphremagog. North of Craftsbury the 

 novaculite is much prized for honestones; those from Lake Memphremagog being very highly prized. In the 

 west part of Coventry, and upon all the northern sections, excellent novaculite is found. Upon Section IX. 

 and elsewhere it degenerates into an impure article, unfit for hones, and passing gradually into the soft 

 talcose schist. But there is an immense amount of this inferior quality of novaculite in this formation. 

 Novaculite schist also abounds in Franklin, Berkshire, etc. upon the western range. 



12. Epidotic Talcose Schist. This is a curious rock, and almost deserves a separate color upon the map. 

 It is all contained in a strip two miles wide and eight miles long (in Vermont), in the towns of Berkshire 

 and Enosburgh. The rock is chlorite schist full of nodules or geodic masses of epidote. The larger ones 

 average an inch in diameter, and sometimes are six or eight. Generally the bunches are a quarter of an 

 inch thick, and are very thickly disseminated so that the rock resembles amygdaloidal trap. Calcite and 

 specular iron are often associated with the epidote. These three minerals are all in crystals and well de- 

 fined. The strata are nearly perpendicular over the whole of this district. This rock is universally regarded 

 as metamorphic. Even those geologists who deny that the gneiss and talcose schist of the Green Mountains 

 are ruetamorphic admit that the presence of " nests of epidote and calcite " are sure evidence of a change 

 from a sedimentary to a crystalline state. In the Cabinet Nos. T \? r and T 1 ^ illustrate the characters of this 

 rock. 



13. Whetstone Talcose Schist. This term is applied to an arenaceous variety, almost a sandstone in some 

 cases, which is widely used for the purpose indicated by the name. It is of a light gray color, compact, and 

 softer than sandstone. Excellent localities of it are in Ludlow, on Abel Adams' land, where it is quarried 

 for whetstones (No. Trz) ', in Marlboro ; the north part of Fairfield (No. T y T ) ; at Plymouth ; in the south 

 part of Stockbridge, upon the land of Mr. Esty ; and elsewhere, particularly in the middle parts of the 

 State. 



HOCKS ASSOCIATED WITH TALCOSE SCHISTS AND CONSTITUTING INTEGRAL 



PARTS OF THE FORMATION. 



These are clay slate, with plumbaginous, aluminous and pyritiferous varieties ; hornblende schist, gneiss, 

 quartz rock, sandstones and conglomerates, limestones and dolomites. Of these the hornblende schists and 

 limestones are considered under separate headings as rocks by themselves. 



1. Clay Slate. There is a distinct belt of this variety in each of the two principal ranges. One com- 

 mences at North Troy, and may be traced southerly through Troy, Lowell, Eden, Hydepark, Morristown, 

 Stow, Worcester and Middlesex. South of Middlesex, along the same general strike, the same belt is seen 

 in Braintree, Rochester, Sherburne and Bridgewater. Want of observation alone prevents us from joining 

 these two lines upon the Map. It probably is found nearly continuously through the State to Massa- 

 chusetts, disguised sometimes as hornblende slate or schist in the more thorough metamorphic region. 

 Plumbaginous shales may be another form in which this variety is disguised. This occurs at Halifax, 

 Somerset, Proctorsville, Bridgewater, Plymouth, Sherburne, Hancock, Cambridge and elsewhere. Those at 

 Hancock and Cambridge are valuable as plumbago. 



The range west of the Green Mountains is in the towns of Richford, Montgomery, Averts Gore, Belvi- 

 dere, Waterville, Cambridge, Underbill, Jericho, Bolton and Huntington. It is marked upon the map. 

 We have a glimpse of a fourth range of clay slate in Sheldon, Fairfield and Westford. The character of 

 these ranges is rather that of shales than of distinct clay slate, except at intervals ; as in the northern part 

 of the eastern range they are invariably black, except when from the decomposition of pyrites they have 

 the color of iron rust. 



The pyritiferous variety includes those strata, not always argillaceous, in which there are a great many 



