GEOLOGY OF THE MERRIMACK DISTRICT. 519 



reaching* its greatest breadth between Washington and Henniker, and 

 coming to a point southerly in Jaffrey. It is sixty-one miles long, fifteen 

 wide in its broadest part, seven and a half in Danbury and Grafton, and 

 three and seven tenths in Wilmot. This area represents the height of 

 land between the Connecticut and Merrimack rivers, which has been 

 stated heretofore to constitute the first territory in the state that was 

 redeemed from the primeval ocean. The normal structure of this mass 

 should be anticlinal. 



Besides this principal mass there are certainly eleven smaller areas, (i) 

 Bean's hill mass, in Salisbury and Warner ; (2) along Schodac brook, in 

 Warner and Webster ; (3) a smaller one in the same towns farther south ; 

 (4) Blackwater river range in Webster ; (5) (6) the continuation of the 

 same in the hill back of Tyler station, and near the village of Hopkinton ; 



(7) the largest one next to the main ridge, in the north part of Weare; 



(8) north-west from Oil Mill station, Weare, perhaps continuous with the 

 outcrops in the north part of New Boston ; (9) a little known area in 

 Pelham ; (10) in East Concord; and (ii) in Alexandria. 



The western boundary of this larger area has been sufficiently well 

 defined by Mr. Huntington on page 469. There are also a few small 

 outliers west of it, as on the west side of Moosilauke in Benton, the north 

 part of Rumney, three miles west of Sunapee lake, one about three miles 

 north of Washington centre, the large range from the east part of Lemp- 

 ster to Marlow, a tract between Thorndike and Gilmore ponds in Jaffrey, 

 and five small patches in Fitzwilliam, besides the oval district in Chester- 

 field and Winchester. These will not be farther alluded to. 



The prevailing rock of this formation is the characterisic gneiss full of 

 distinct crystals of feldspar. More than one species of feldspar may be 

 present. The different areas are characterized by special features of size 

 of crystals, their arrangement, or frequency of occurrence, so that it is 

 possible to identify the source of boulders that have travelled several 

 miles. Other layers consist of ordinary gneiss, ferruginous schists, and 

 mica schists passing into quartzite. These associated rocks occasionally 

 predominate, and the perplexing query often arises, Where shall we draw 

 the line between this and the superior formations .'' Rocks repeat them- 

 selves in different ages, so that we have mica schists, etc., associated with 

 the oldest as well as the newest formations, and it is not always possible 



