GEOLOGY OF THE CONNECTICUT VALLEY DISTRICT. 403 



7. The Ascutney Area. 



Mt. Ascutney is the highest mountain immediately adjoining the Con- 

 necticut river in any part of its course. The nearest one to it is Bovvback, 

 in Stratford, which falls short of it about two hundred feet. Ascutney is 

 also more conspicuous than any other mountain near the river, since it 

 rises from a lower plain. It is essentially a cone, nearly three thousand 

 feet higher than the river at its eastern base, only three miles distant ; 

 and there is a small subordinate cone on the west. The principal cone 

 is composed of eruptive granitic material. The smaller mountain is in 

 part eruptive, but is mainly made up of gneiss of Eozoic times, probably 

 older than Montalban. The larger mountain rises from a fissure cutting 

 directly across the Calciferous mica schist, indurating but not greatly dis- 

 arranging the course of the strata. 



Our map shows a strip of gneiss in Vermont, extending from Marl- 

 boro', or Athens, to Hartland. This has a narrow band of hornblende 

 schist upon both sides of it. We should have been glad to study it 

 carefully, but it lies outside of our field of labor. It is thought to agree 

 with the gneiss of our Lake period, while some parts of it resemble the 

 Montalban. Its environment by the hornblende suggests its eciuivalency 

 with the Bethlehem group of Cheshire county, where a similar concen- 

 tricity is displayed. Upon Section V we find a very distinct anticlinal in 

 the south part of Reading, just west of Little Ascutney. It is our theory 

 that that range of gneiss is a repetition of the Green Mountain rock, and 

 that both are older than the intermediate Huronian. The Ascutney rocks 

 are situated on the east side of the northern part of this ancient gneissic 

 range; and the eruptive portions cut across both this older rock and the 

 adjacent Calciferous mica schist. A careful delineation of the boundary 

 between these two formations, upon both sides of the eruptive mass, indi- 

 cates the course to be the same, and to have been continuous before the 

 eruption. The erupted materials came from an east and west rent in the 

 strata ; and, in consequence of the abundant liberation of heat at the time 

 of their protrusion, the character of the limestone and other rocks adja- 

 cent to it has been changed. 



There is reason to believe the nucleus of Little Ascutney belongs to a 

 period distinct from either the Lake gneiss or the eruptive age. There 



