GEOLOGY OF 1 HE CONNECTICUT VALLEY DISTRICT. 4OI 



an inverted synclinal to the cast of Strafford Centre ; a normal anticlinal 

 in the west part of the town ; a synclinal in South Tunbridge ; an anticli- 

 nal, followed by a synclinal, beneath argillaceous schist; and an anticlinal 

 again before touching the western band of Cambrian slate at Bethel. On 

 Section VIII there may be a band of Coos rocks in Newbury, consisting 

 of argillaceous seams much twisted and devoid of limestone, in a possi- 

 ble anticlinal aspect. The Calciferous group succeeding is mostly lime- 

 stone; and four or five duplications may be made out in it before coming 

 to the central hill in Washington, where we find a very low easterly dip 

 of massive limestones. These supposed duplications are monoclinal, with 

 various degrees of dip. From this central range the dips are all westerly 

 to the slates of Northfield, with certainly indications of three axes, occa- 

 sioned by different inclinations of the strata. As originally published, 

 this section seemed to be one gigantic anticlinal; but our repeated ob- 

 servations indicate the existence of several closely pressed folds upon 

 both sides of the centre, and this middle point may be the newest part 

 of the formation. Sections V-VIII were carefully resurveyed by me in 

 1875, and hence are understood in greater detail than before. 



Section IX loses its central hill of limestone, and its place is taken by 

 an enormous mass of granite, perhaps erupted in a period subsequent to 

 the deposition of the limestone. On the west side of it is a satisfactory 

 synclinal overturn at its junction with the western band of Huronian. 

 On the east the dips are monoclinal, probably all overturned to the east. 

 Section X is more singular still. Most of the area is a high table-land 

 of limestone, the recurrence of the Washington ridge ; and at both sides 

 there is a narrow synclinal, closely pressed and adjoining Cambrian slates. 

 Section XI shows the central plateau, disturbed and broken in two by 

 eruptive granite. On the east the inclination is gentle towards the rising 

 sun ; and at East Burke the crowding westerly of the older rocks has 

 inverted the limestones to dip high to the west, and thus show a syn- 

 clinal basin. West of the granite are two regularly formed basins, sepa- 

 rated by a symmetrical anticlinal. This is succeeded by a smaller por- 

 tion of the schist caught in eruptive granite adjacent to the Cambrian 

 slates. Section XII gives us an anticlinal in Brighton, elevated appar- 

 ently by an upward push of granite. It joins an older granite directly 

 on the east side, as the slates usually bordering it farther south have 

 VOL. II. 51 



