512 ASSOCIATED KOCKS. 



crystals of iron pyrites. At least a fourth part of the three ranges is more or less stained by this rust. In 

 the west range, through Underbill, Jericho, Bolton and Huntington, a ferruginous strip is particularly notice- 

 able. In Hydepark, Morristown and Worcester there is another unusually ferruginous, in which gold and 

 associated minerals occur. Other localities are too numerous to mention, and many are noticed upon the 

 section. 



Aluminous slate is connected with these imperfect clay slates. The sulphuric acid for the alum results from 

 the sulphur of the pyrites, and the alum produced is an iron alum. Copperas also may result ; but both these 

 compounds do not accumulate because they are washed away by the rain and snows. 



2. Gneiss. This is not abundant. It is chiefly found along the borders of the formation where it con- 

 nects with gneiss. Specimens of gneiss in talcose schist have been obtained from Marlboro, Wilmington, 

 Proctorsville, Ludlow and Plymouth. 



3. Quartz Hock. In the town survey of Plymouth, Mr. Hager found that there were two beds of quartz 

 (See Plate XVIII) in the talcose schist running through the town. Their curves are due to the topography 

 of the surface. The character of the quartz is that of a milky white or else transparent variety. Without 

 doubt a careful exploration would discover that these two belts are continuous throughout the State. 

 They are quite near each other, and hence might be confounded together elsewhere ; and hence we will 

 mention the localities in other parts of the State, which may possibly be the continuation of these in 

 Plymouth, West Marlboro, South Wardsboro, North Wardsboro, Ludlow, Bridgewater, Eochester, Middle- 

 sex ; and in Johnson there are two beds of quartz rock each ninety feet thick. About Hazen's Notch for five 

 or six miles the surface is covered with bowlders of a very tough quartz rock. A range of a similar rock , 

 says Kev. S. R. Hall, is found near the top of the Green Mountains through the whole State. Probably this 

 range is the same with the one in Plymouth. Other masses of quartz are common through the talcose 

 schist, especially thin strata of brown quartz. They will be found mentioned upon the catalogue, and are 

 of too little consequence to be specified separately. 



4. Sandstones and Conglomerates. Considerations have been presented to show that talcose schist may 

 be produced from sandstone by metamorphism. Much of the schist was probably sandstone originally. 

 The east part of the western range is now clearly a sandstone, as may be seen among the specimens upon 

 Section XI. The grains of sand are cemented by talcose matter, and the whole rock is very compact. 



The section along Winooski Eiver exhibits several strata of sandstone. The amount increases upon each 

 section north. In Hydepark and Wolcott it is better characterized than on Section IX, and in Troy it is 

 quite distinct. In Canada along the line of strike, very much of the rock is sandstone the Sillery sand- 

 stone of the Canada Survey. A large bowlder from Canada was examined as it lay in the north part of 

 Brownington, and was found to be a conglomerate of quartzose fragments, and pieces of limestone 

 containing pentacrinites. Nothing of that description has been found in situ in Vermont. 



A single bed of a very coarse conglomerate occurs in Coventry at Charles Wright's house in the north- 

 west part of the town, and also three miles south, which is doubtless of the same age with the bowlder. 

 The fragments are from two inches to over two feet in diameter, being composed of various kinds of slates 

 and schists, some of which are decomposing quartz pebbles, granite pebbles, etc. It is more interesting 

 because it is at the base of the talcose schist formation, overlying a narrow bed of upper Silurian lime- 

 stone and clay slate. Nothing elsewhere in the State is like it, unless it be a coarse conglomerate passing 

 into porphyry upon Little Ascutney. 



5. Igneous Rocks associated with this formation. There are small outbursts of granite, several trap 

 dikes, and a few ledges of concretionary granite like that at Craftsbury in the calciferous mica schist. 

 A semi-igneous rock in a breccia with a syenitic paste is in Barnet upon Connecticut River. A breccia with- 

 out this paste occurs further south at Newbury. Connected with it is a very indurated talcose sclu'st, 

 slightly resembling serpentine. A coarse rock with black spots of argillaceous matter more or less calcareous 

 is abundant about White River Junction. The eastern range is different from the others by being largely 

 composed of these rough semi-igneous brecciated rocks. They will be described fully under igneous rocks. 



There is an indurated talcose schist in the southeast part of Troy at Levi Brooks' house. It passes into 

 granite. Granite is also found in the talcose schist in Plymouth (See Plate XVIII), Braintree, northeast 



