GEOLOGY OF THE MERRIMACK DISTRICT. 553^ 



and thus making the range touch the south-east corner of Mont Ver- 

 non. 



The Dcerfield and Mason Range. We are introduced next to a ma- 

 terial somewhat different from the ordinary gneiss of the Lake series. It 

 is thoroughly and coarsely crystalline, being generally much more sac- 

 charoidal in appearance than even the typical varieties about Winnipi- 

 seogee, and not so fine. It is more like the Laurentian gneiss of typical 

 localities than anything else in the state, except a range of similar type 

 passing through Berlin. In some early publications I have spoken of 

 this formation as the Manchester or Berlin gneiss. Were it not for mul- 

 tiplying distinctions it might be well to separate this from the other 

 ranges ; but it approaches the Lake gneiss more nearly than anything 

 else, and therefore may be classed with it. Supposing it to underlie the 

 series associated with the quartzes, it would be repeated in the Weare 

 and Dunbarton range on their north-west side. The latter are very 

 crystalline in their aspect, though readily referred to the Lake series. 



Another peculiarity of the Manchester range consists in its ready pas- 

 sage into granite, together with a disposition to a minute twisting of the 

 strata. The readiest method of understanding this peculiarity is to 

 imagine a thorough squeezing of the rock from both sides, and then a 

 melting of the curled layers sufficiently to cause many of them to disap- 

 pear by conversion into genuine granite. Much of this rock would 

 pass for a true granite, full of miscellaneous patches of twisted strata of 

 mica schist. There are also bands of a coarsely crystalline mica schist 

 connected with this gneiss, which are of the same age, and not to be con- 

 founded with the later formation so extensively developed in Rockingham 

 county. 



This range extends farther east than Deerfield, but our descriptions 

 must commence with the line separating the Merrimack and Coast dis- 

 tricts, which is the height of land between the hydrographic basins of the 

 Merrimack and the Lamprey and Exeter rivers on the east. On reference 

 to the map it will appear that Deerfield is mostly excluded from the Mer- 

 rimack district ; Candia is divided transversely into equal parts ; Chester 

 is mostly east of it, and Derry is situated upon both sides of the line. 



The following represents the rocks on a line from Campbell's hill, in 

 Hooksett, to the Candia ridge. Campbell's hill is of quartz. Half a mile 

 VOL. II. 70 



