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NEW HAMPSHIRE. 



891 



tlie laat being at the top. Tlie Lrccciatcd granites of Franconia seem to be 

 older than any of these, and to underlie them If these points are as- 

 sumed, the porphyritic gneiss can be shown to be at the bottom of the series, 



for it lies outside of the lowest of them We cannot as yet locate the 



andalusite gneiss, save that it is newer than the porphyritic bands as shown at 



Moosilank The Coos group of Littleton and Lisbon passes around the 



west c]id of the Bethlehem gneiss, showing that the latter existed before either 

 the deposition or elevation of' the former. This indicates that the whole of 

 the Wliite Mountain rocks are more ancient than the Coos and Quebec groups 

 of the Connecticut valley." (/. c, pp. 25-27.) 



In the Report for 1872, the Quebec group of the earlier reports is 

 assigned to the Hurouian. The Porphyritic group is described as con- 

 sisting 



" mainly of f^neiss full of large crystals of orthoclase fehlspar, associated with 

 ferruginous and other bands. It is regarded as the oldest of all the formations 



in the State for these reasons : 



" 1. The principal range is flanked on both sides by similar varieties of gneiss, 



and later series of rocks in the same order. The newer groups being outer- 



mostj the anticlinal rather tlian the synclinal structure is suggested, and hence 



the greater antiquity of the central range. 



** 2. This rock is apparently covered by the other members ot tne gneiss 

 series in the northern part of the State. 



"3. The lithological chamber [? character] corresponds with that of known 

 Laurentian strata iu Canada, North Carolina, and elsewhere." (/. c, p. 11.) 



Of the " Concord granite " Prof. Hitchcock says : 



" This rock is not a proper granite. There is an arrangement of the parti- 

 cles of mica along parallel planes, which allows the rock to split readily. 

 These we regard as strata." {L c, p. 12.) 



In 1872 Professor Hitchcock presented the following classification of 

 the rocks of New Hampshire : 



;'ii 



% 



i'\ 



** I. EozoiG. 



" 1. Laurentian, including (a) porphyritic gneiss ; (h) White Mountain series, 

 r andalusite gneiss ; (c) Bethlehem, or talcose gneiss ; (d) gneiss of Lake 

 vVinnipiseogee Basin ; (c) gneiss on both Hanks of the porphyritic variety in 

 the south part of the State, subdivided by bands of qnartzite, — this carries the 

 Concord and FitzAvilliam granites, and is probably the beryl-bearing series also ; 

 (/) range of gneiss between AVhitefield and Milan, considerably hornblendic. 



** 2. Norian, including (a) common granite ; (h) trachytic granite ; (c) four 

 bands of felsite, both labradorite and orthoclase. 



" 3. Exeter syenites, including those cutting the Norian at Waterville, Mount 



I*"onadnock, opposite Colebrook, Bedhill, &c. 



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