272 STRATIGRAPHICAL GEOLOGY. 



New Hampshire border, as in Cornish, Claremont, Lyme, and Orford ; 

 third, the upland tracts underlaid by the micaceous schists and quart- 

 zites. These varieties result from the character of the ledges ; and, as 

 stated heretofore, the soils of the Connecticut valley are among the best 

 in the state. 



For convenience in our descriptions, the rocks of this district will 

 be described under four topographical divisions : first, the Ammonoosuc 

 Gold field ; second, the balance of the northern section, extending suffi- 

 ciently far south to embrace the Mt. Ascutney rocks ; third, the southern 

 section of the district from Charlestown to Chesterfield, opposite Brattle- 

 borough, Vt.; fourth, the Helderberg region, embracing Hinsdale, part of 

 Winchester, Vernon, etc., Vt., and parts of Northfield and Bernardston, 

 Mass. Whatever facts we may happen to possess respecting the rocks 

 of the western part of the district, in Vermont, will also be presented, 

 though our information of that part of the area is not extensive. Enough 

 is known of the rocks on the western side of the river to render feasible 

 the presentation of the geology of the whole district. The boundaries of 

 states are not usually the natural limits of formations, so that we must 

 trespass a little upon the Vermont territory. Our general geological map 

 will be seen to extend into that state about the width of two townships, 

 except in Essex county, where more land is included. We have been 

 enabled thus to extend our map, through personal investigations in con- 

 nection with the Vermont geological survey, and more recently in contin- 

 uing our section lines across to Lake Champlain, for the benefit of the 

 museum. 



THE AMMONOOSUC GOLD FIELD. 



This field embraces the territory bounded west by the Connecticut 

 river, north by the town of Dalton, cast and south by the older gneissic 

 areas, or from the west border of Bethlehem, through the eastern parts 

 of Lisbon and Landaff, to the northern part of Haverhill, and thence to 

 the Connecticut river. This embraces the whole of the towns of Little- 

 ton, Monroe, Lyman, Bath, and parts of Haverhill, Landaff, and Lisbon. 

 It is all expressed on the small geological map in the first annual report 

 (1869), and also in Fig. 27. The large map in the Atlas docs not quite 

 cover the whole ground, it being confined to the space between the 



