DESCRIPTION OF THE GENERAL SECTIONS. ^l*] 



clinal. On reaching Greenville we are introduced to a considerable 

 breadth of the ferruginous and other mica schists most, likely connected 

 with the Montalban series. The westerly dips prevail entirely through 

 New Ipswich, but we have shown in Fig. 94 a basin of mica schist over- 

 lying the older rocks, reaching from the village to the east base of Barrett 

 mountain. It is likely an anticlinal is present in Barrett mountain, which 

 is the mountain ridge between the Merrimack and Connecticut valley 

 depressions. Between the east line of Rindge and Peasley pond are two, 

 perhaps three, axes in the ferruginous group of the Montalban. In Fitz- 

 william there rises to the surface a little porphyritic gneiss, with the pecu- 

 liar granite of the region upon both flanks. There is a difference of opin- 

 ion whether the latter rock is a true granite or gneiss, whose planes of 

 stratification are usually obliterated. There are also two appearances of 

 the Bethlehem series in Fitzwilliam. In the west part of the town the 

 Montalban rocks dip 75° westerly, making a sharp synclinal with the same 

 strata in the east part of Richmond ; and there is another anticlinal be- 

 fore reaching the village. From this village through the rest of the town 

 and the principal part of Winchester the gneiss is thought to belong to 

 the Bethlehem series, with quite variable dips. There would be the basin 

 structure before reaching Muddy brook, perhaps a second synclinal in 

 the valley of that stream, though this is not clear, and a very distinct 

 anticlinal between Muddy brook and the tributaries of Perchog river. 

 This gneiss distinctly and unconformably underlies the Coos quartzites, 

 the point of contact being visible. This comparatively modern group 

 furnishes three ranges of quartzites before coming to Connecticut river, 

 which are supposed to constitute one band repeated, and to underlie the 

 mica schists, the latter assuming the basin shape, and carrying notable 

 quantities of indigenous granite. 



The quartzite crops out on the west side of the river at South Vernon. 

 As the next seven miles have been described already with much detail 

 (p. 437, Fig. 71), it will be unnecessary to repeat the observations here. 

 To the west of the Cambrian are easterly-dipping slates, at Fall river. 

 Guilford will be found represented in a basin of the Calciferous mica 

 schist, followed by an anticlinal ridge of hornblende schist, supposed to 

 be Huronian. The sheet ends with the repetition of the calcareous 

 rocks on the west side of the hornblende. 



