NEW HAMPSHIRE. 391 



the last being at the top. The brecciatecl granites of Franconia seem to he 



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



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 



Moosilauk The Coos group of Littleton and Lisbon passes around the 



west end 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 White Mountain rocks are more ancient than the Coos and Quebec groups 

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



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

 assigned to tlie Huronian. The Porphyritic group is described as con- 

 sisting 



" mainly of gneiss full of large crystals of orthoclase feldspar, associated with 

 feiTuginous 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- 

 most, the anticlinal rather than the synclinal structure is suggested, and hence 

 the greater antiquity of the central range. 



" 2. This rock is apparently covered by the other members of the gneiss 

 series in the northern part of the State. 



"3. The lithological chamber [? character] corresponds •with that of kno^^^l 

 Laurentian strata in Canada, North Carolina, and elsewhere." {I. 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." {I. c, p. 12.) 



In 1872 Professor Hitchcock presented the following classification of 

 the rocks of New Hampshire : — 



" I. Eozoic. 



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

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

 Winnipiseogee Basin ; (e) gneiss on both flanks of the porphyritic variety in 

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

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

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



" 2. Xorian, including (a) common granite ; (b) trachytic granite ; (c) four 

 bands of felsite, both labradorite and orthoclase. 



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

 Monadnock, opposite Colebrook, Redhill, &c. 



