DESCRIPTION OF THE GENERAL SECTIONS. 645 



structure will appear to better advantage farther north, because it has 

 been studied there. The clay slate of the lower sections seems to be 

 wanting on Section IV, unless it be buried beneath the alluvium. 



Section V. 



We have satisfactory data for the delineation of the whole of this 

 section, from the extreme eastern limits in Alfred, Me., to Reading, Vt., 

 a distance of ninety-five miles. It passes through Alfred, Sanford, Shap- 

 leigh, and Acton, Me.; Milton, Middleton, New Durham, Alton, Gilman- 

 ton, Belmont, Tilton, Franklin, Andover, Wilmot, Springfield, Grantham, 

 edge of Croydon, and Cornish, N. H.; Windsor, including Mt. Ascutney, 

 West Windsor, and Reading, Vt. 



The Maine portion of this section has been illustrated sufficiently well 

 in Fig. 108, PI. XXV, and the accompanying description. The first rock 

 in our state is the Rockingham group, showing several undulations in the 

 first two towns, usually of little general consequence. The presence of 

 the andalusite schist on the east of a prominent anticlinal in Acton sug- 

 gests the possibility of finding the same repeated in the east part of Mil- 

 ton. In Middleton may be seen Montalban rocks underlying the mica 

 schists of Milton, imperfectly developed on account of the abundance of 

 drift scattered everywhere as a thin covering over the ledges. The axes 

 through to Lake Winnipiseogee are noted upon page 603. On the west 

 side of Alton bay is a large ledge of sienite ; and near the travelled road 

 no other ledge has been noticed, except one of mica schist on the sum- 

 mit, dipping 70° N. W. This is the northern end of a large area of this 

 description, repeated on reaching Gilmanton. Between Pine mountain 

 and Place's pond are areas of porphyritic gneiss, with vertical strata, and 

 sienite. The Rockingham group through Gilmanton and Belmont is char- 

 acterized by the presence of numerous minor undulations, six or more in 

 number. Among them is a synclinal constituting the ridge of Grant and 

 Lamprey mountains ; and the place of an inverted anticlinal west of Bel- 

 mont village, occasioned by the underlying gneiss. Another well-marked 

 gneiss area appears in Northfield. At Tilton the dip changes abruptly, 

 since the rock is different, most likely Montalban, the beginning of the 

 Merrimack Valley area of this formation. Near the west line of Franklin 

 appears the anticlinal in it, caused by the extension northward of the 



