GEOLOGY OF THE WHITE MOUNTAIN DISTRICT, 2$ I 



boundaries of the Bethlehem group. 695 and 719 belong to the Lake gneiss. Then 

 there are two small areas of the Coos mica schist. AH the numbers bordering the 

 Ammonoosuc river in West Bethlehem and Littleton, save those belonging to Section 

 IX, will be found enumerated in the catalogue of the Ammonoosuc region, likewise 

 everything in Lisbon. The smaller numbers in Landaff, Benton, Warren, Ellsworth, 

 parts of Sandwich, Tamworth, Madison, Eaton, and Conway, are mostly from the gen- 

 eral catalogue of lithological specimens, numbered in continuation of that ending on 

 page 86. The areas of the several formations are inclosed by heavy lines, the naiTow 

 ones representing the 500-feet contours. The names of the various locations, grants, 

 mountains, ponds, rivers, etc., may be learned by comparison with other maps in the 

 Atlas. The dips of the strata are given so far as we have reliable information concern- 

 ing them. 



Final Statement of Opinions. 



This chapter will not be complete without a rhwn^ of the present 

 opinions held by the writer respecting the age and elevation of the 

 White Mountains. I have quoted everything of importance written by 

 others respecting them, from the convulsion theory of Dr. Dwight to the 

 proposal of the existence of an undescribed formation, by Dr. Hunt. I 

 cannot further advert to the gradual progress of our views, than to refer 

 to the chapters upon the history of the present survey, and a few im- 

 provements upon them suggested while this volume has been passing 

 through the press. A few statements in the early part of this chapter 

 have been modified by later explorations, and the changes are mentioned 

 farther along. I propose now to state briefly the general conclusions 

 obtained respecting the age and equivalency of the formations, and the 

 principal physical changes effected in the condition of the district. 



The order of the systems seems to be the following: First, the Lau- 

 rentian, represented by the porphyritic gneiss and the Bethlehem group. 

 Second, the Atlantic, consisting of the Lake or Berlin and Montalban 

 gneisses, and the Franconia breccia. Third, the Labrador, Fourth, the 

 Huronian, Fifth, the Merrimack schists. Sixth, the Andalusite schist 

 group. Seventh, eruptions of porphyry. Eighth, eruptions of the Con- 

 way, Albany, and Chocorua granites and sienites. Ninth, the formation 

 of the Mt, Pequawket or Mt, Mote porphyritic breccia. This order is 

 somewhat different from that stated at the beginning of the chapter, 



1. Lanrentian. Dr, Hunt has expressed to me his opinion that both 

 the porphyritic and the Bethlehem gneisses agree essentially in litho- 

 logical character with the schists he has observed in typical Laurentian 



