632 STRATIGRAPHICAL GEOLOGY. 



on the line between Greenland and Stratham, in the edges of Stratham 

 and North Hampton, and on the confines of North Hampton and Exeter, 

 west of J. L. Philbrook's. The west border of this point is composed of 

 felsite. In the west part of Hampton Falls are exposures by E. C. San- 

 born's, and next to a tributary of Taylor's river. At Sanborn's there has 

 been an opening for mining- purposes which reveals an intrusive diorite, 

 bunches of ankerite, plates of calcite, chlorite, crystals of smoky quartz, 

 narrow quartz seams, etc. The farthest exposure seen of sienite in this 

 range is near Miss Page's, in the south-cast part of Kensington. Its 

 further course is concealed by an abundance of till. 



The last of these areas is that of Seabrook, which is the north end of 

 the Massachusetts mass. The western limit of it is where the Eastern 

 Railroad crosses the state line. It extends a mile and a half into the 

 township, and is then covered by drift. In the marshes opposite Bound 

 Rock the natural continuation of the sienite is taken by a granite. I 

 have examined a few ledges of sienite in Salisbury, Newburyport, and 

 Byfield, and have copied the delineation from the Massachusetts map. 

 Our observations develop nothing additional to what has been already 

 published by my father. There may be some further notice of these 

 rocks under the topic of Economic Geology. 



The sienite of Mt. Pawtuckaway in Deerfield and Nottingham is repre- 

 sented as like that of the Belknap mountains. As it is midway between 

 the different areas, it is also intermediate in character between them. 

 Situated in the midst of gneiss, it does not afford evidence of age when 

 compared with the various mica schist groups. Like the more northern 

 variety of rock, it is accumulated in a mountain mass, and cannot easily 

 be esteemed a gneiss slightly altered. 



The granites of our south-east sheet are of little moment, apart from 

 the numerous beds interstratified with mica schists, which have been 

 mentioned in their proper places. The granite of South Kingston and 

 in Andover, Mass., has been already alluded to. There is a very large 

 granitic area in North Berwick, Sanford, and Alfred, Me., which is more 

 like the Mt. Bet series of New Durham than anything else described in 

 New Hampshire. It may be that some of the sienitic area to the south 

 of Newburyport is to be regarded as granite. 



The trap dykes are well represented in this district. Concerning one 



