252 STRATIGRAFIIICAL GEOLOGY, 



regions; and Prof. Dana (p. 109) has discovered similar resemblances in 

 the upper member of the second group. Our observations lead to the 

 behef that they are the oldest formations in this district, and suggest 

 that they may belong to the upper division of the Laurentian system as 

 it is developed in Canada and New York. We have two leading and 

 divergent ranges of the porphyritic group, each suggestive of an anticli- 

 nal structure (PI. VI, Fig. 7 and Fig. 12), the first underlying the Beth- 

 lehem gneiss. The Bethlehem group is noted for a nearly east and west 

 strike, is marked by an anticlinal structure when flanked by the Lake 

 gneiss (Fig. 11), and has porphyritic beds in its lower member. The 

 Bethlehem synclinal, if correctly interpreted, is inverted. We may note 

 the improvement of Plate VI, Fig. 7, above the statements upon page 1 10, 

 and the development of the eastern range in Waterville, coming up again 

 also in Albany, near the western line. More irregularities appear in its 

 course in Sandwich. 



2. Atlantic. The lowest division of this newly-described system is 

 best developed in the more northern part of the White Mountain dis- 

 trict, the rocks having been partially described in Chapter II. They are 

 the "Older rocks" (p. 6j) and the "Granite and granitoid gneiss (p. 'j-'^. 

 The Berlin gneiss seems to constitute an anticlinal axis, with both Huro- 

 nian and Montalban schists overlying each flank (Figs. 4, 5, and 6). This 

 band possesses a very inferior development in this district south of Jef- 

 ferson, because the principal mass lies to the west of it. The limited 

 range from near Mt. Hale across to Franconia appears to overlie both 

 the porphyritic gneiss and Franconia breccia, and to correspond to the 

 Whitefield, Jefferson, and Littleton outcrops on the other flank of the 

 older groups. Its continuity across Franconia is interrupted by a south- 

 erly extension of the Bethlehem, as if it had been worn away down to a 

 lower formation. In Sandwich we perceive the commencement of the 

 large Winnipiseogee Lake development of this series, as well as the 

 smaller area embracing the Dome. 



The Montalban portion of the Atlantic system has a large representa- 

 tion in this district. It constitutes the foundation of the principal higher 

 range of mountains from Success across the Androscoggin river to Mt. 

 Webster, and is then supposed to continue beneath the granites and por- 

 phyries to connect with the same series in Thornton and Waterville, 



