48 PHYSICAL GEOGRAPHY. 



MICROSCOPICAL RESEARCHES. 



In view of the importance of microscopical researches, not only in 

 gaining knowledge of the mineral structure of rocks, but also of the 

 " polishing powder" and other valuable minerals abundant in the state, 

 we organized a new department of the survey in 1870, and obtained the 

 assistance of Professor A. M. Edwards, of Newark, N. J., and Professor 

 T. Egleston, of the School of Mines, Columbia college, New York. 

 Professor Edwards has prepared an extensive report upon the organisms 

 producing the lacustrine sedimentary deposits ; and Professor Egleston 

 has had charge of the cutting and description of rock sections. 



FOSSILS ix NEW HAMPSHIRE. 



In October, 1870, while examining the limestones of Littleton, fossil 

 corals were discovered. They were quite numerous, though obscure. In- 

 telligence of the discovery was immediately telegraphed to the Dartmouth 

 Scientific Association, who happened to be holding a meeting the same 

 evening. It was announced to them that New Hampshire could no 

 longer be called an Azoic state, since she had within her borders a coral 

 reef of Silurian age. 



Specimens were sent to E. Billings, F. G. S., paleontologist of the 

 geological survey of Canada, who recognized the genera Zaphrentis and 

 Favosites, and perceived the probable equivalency of these limestones 

 with the Helderberg series of Memphremagog. The band of rock was 

 at first supposed to be the same with the limestones of Dalton and 

 Lancaster, and perhaps farther north. The fossils have been discov- 

 ered in two localities, nearly two miles apart, upon what is thought to be 

 the two sides of a synclinal axis. The limestone is underlaid by a 

 quartzite and covered by a clay slate, the latter containing impressions of 

 worm tracks. Though previously announced, this is believed to be the 

 first authentic discovery of fossils in the solid rocks of New Hampshire. 



No time could be devoted to this interesting department till 1873, when 

 our labors were rewarded by the discovery of fossils characteristic of the 

 Lower Helderberg. Mr. Huntington was so fortunate as to find, on 

 Fitch hill, Littleton, specimens of brachiopods, a gasteropod, and large 



