360 STRATIGRAPHICAL GEOLOGY. 



In Orford the Huronian is wanting, unless it is connected with the 

 soapstones of Sunday mountain and the quarry of Mr. Strong in Orford- 

 ville. In Lyme a narrow strip occurs above Gilbert's bridge, close to the 

 river. Large ledges by E. P. Snow's, in the north-west corner of the 

 town, dip easterly about 70°, and the same at the North Thetford bridge. 

 Dolomite occurs between these two localities, Fig. 53 showing the rela- 

 tions of the Huronian and Coos groups in North Lyme. None of the 

 greenstones crop out in Hanover or Lebanon, but they cross in great 

 force from Hartland into Plainfield. 



The range is continuous from Fairlee southward in Vermont through 

 Thetford, Norwich, and Hartford. I have not separated the two groups 

 below Fairlee as yet upon the map. On the first hill north of North 

 Thetford, hard siliceous schists dip S. 60° E. at their contact with slate. 

 A mile east of Thetford hill the green schists dip 80° N. 30° W. At a 

 school-house still farther east, perhaps two thirds of the way to the sta- 

 tion from the hill, is a quartzite dipping north-westerly 50°. This may 

 indicate the eastern limit of the Huronian. Following these rocks to 

 Union Village we find them making an anticlinal, with a strike to the 

 north-east, where cut down deeply by Pomponoosuc river. The ledges 

 of this rock extend through Norwich, are abundant, and have been deter- 

 mined with much pains. The ledges in the north part of the town are 

 allied to the greenstones holding fossils. A range of argillaceous schist 

 lies in the Huronian, extending from a little north of the station for two 

 or three miles. It undoubtedly shows the place of a synclinal line. By 

 a windmill, half a mile above Hanover bridge, the hornblende comes in 

 contact with greenstones; and in a railroad cut adjacent there is a large, 

 unconformable mass of serpentine. Somewhat similar schists make the 

 cliff for half a mile above. A similar junction appears in railroad cuts 

 south of the depot, as near the paper-mill. On that line we have, going 

 west, hornblende schist (the Observatory range) dipping 46° N. 85° W.; 

 serpentinous mass above it; soft slaty layers, dipping 70° N. 57° W., 

 separated from the last by a quarter of a mile of earth covering ; green 

 schists, with dolomitic layers, vertical, having a strike of N. 5° W.; schists 

 dipping N. 30° E.; on the ridge, both hard and soft vertical schists; and, 

 lastly, in the road, half a mile from the depot, dioritic rock dipping 50° 

 N. 70° W. The Meeting House hill, a mile north of Norwich village, is 



