HISTORY OF GEOLOGICAL SURVEY. 55 



Strata perfectly. The latter appear to be identical with the Concord stone. Micro- 

 scopic sections, when available for study, will add much to our knowledge of this 

 variety of rock. 



By scrutinizing the course of a band of rock closely packed with andalusite, it 

 appears probable that the valuable soapstone of Francestown is continuous into Weare, 

 as well as extending farther south-west. Outcrops have been found in four localities. 

 The soapstone of Richmond resembles it also, and seems to be on the same course. 

 Hon. M. A. Hodgdon, of Weare, has made an extensive excavation in this bed on Mt. 

 Misery, which throws considerable light on its character. 



Mica Schist. This formation covers a great area in Rockingham and Strafford 

 counties. In general it is a simple compound of mica and quartz, resembling an 

 argillaceous rock at times, and often showing the mica in irregular blotches. It every- 

 where contains beds of a very coarse granite. In the south part of Rockingham, in 

 Barrington, Strafford, and elsewhere, the granite remains in ridges, while the schist has 

 decomposed, thus making one believe granite to be the prevailing rock of the country, 

 without carefiil search for the schist in the valleys. 



The sienites of Exeter bound this group on the east. The Merrimack group seems 

 to be distinct from it, though the two have been confounded together heretofore. 

 This rock forms mountain masses in many towns. Such are the ridges between Hill's 

 Comer and Shaker Village in Canterbury, the Pinnacle and Bean hill in Northfield, 

 Catamount Mount in Pittsfield, Brush hill, McKays, Fort, and Nottingham mountains 

 in Epsom, Saddleback Mount in Northwood, Devil's Den in Auburn, ridges in Farm- 

 ington, etc. Narrow patches of mica schist occur resting in synclinal form on the 

 gneiss west of the Merrimack river, but it is of no use to attempt to represent them 

 at present. 



Geological History of Winnipiseogee Lake. 



The results of a tour in the vicinity of Winnipiseogee lake, in 1873, are 

 given in a lengthy paper read before the American Association for the 

 Advancement of Science, at Portland, in August. The greatest detail of 

 the sketch relates to the supposed appearance of the lake country in the 

 glacial and terrace periods, which need not be reproduced here. But I 

 desire to state the phase of opinion expressed in this communication 

 respecting the older groups. A large manuscript map illustrated to the 

 geologists at the meeting the distribution of the formations deposited in 

 the several periods enumerated. There are some new groups in this list. 

 We can trace no less than ten periods in the history of this lake basin : 

 I. Period of the deposition of the Porphyritic Gneiss or Granite. This 

 is the oldest formation in the state. A range of it starts southerly from 



