GEOLOGY OF THE WHITE MOUNTAIN DISTRICT, 221 



At Loon Pond. A similar rock crops out a little east of Loon pond, 

 seven miles distant. The area is probably a quarter of a mile in length. 

 The specimen brought from there agrees closely with that just described 

 from the south end of the Lafayette range. Between Loon pond and 

 the most southern end of the orthoclase felsite on Mt. Flume, the dis- 

 tance is four and a half miles, so that the last named area is entirely 

 isolated from all related rocks. The mountain east of the pond is com- 

 posed of Albany granite. 



In the report for 1871 the orthoclase and labradorite fclsites were re- 

 garded as intimately associated together, and forming parts of one sys- 

 tem. As some doubts have been expressed by geologists upon this 

 point, I will now describe them separately, and represent them as dis- 

 tinct from each other upon the map. The latter will be spoken of under 

 the head of Porphyry. A few of the small areas, formerly thought to be 

 labradorite, prove now to be orthoclase. Such are the rocks on the west 

 side of Mt. Tom, and the first peak north of Mt, Andalusite near the 

 Crawford house. Rocky Branch in Bartlett, and the west side of Sable 

 mountain in Jackson. There is labradorite in a breccia from the last 

 named locality, and also from the head of Sabba Day brook in Waterville, 

 and upon Little Deer brook in Albany. It was thought at one time, also, 

 that certain portions of the Chocorua granites contained lime-feldspar. 

 All these specimens will be studied more carefully hereafter; and, in the 

 part of the report devoted to mineralogy and lithology, the reader will 

 find their characters stated with much precision. The necessity of devot- 

 ing our whole time to the general description of the formations has pre- 

 vented us from giving the proper amount of attention to lithology, that 

 is really demanded as preliminary to stratigraphy. There can be no mis- 

 take as to the localities, since the catalogue and map, at the close of this 

 chapter, will make all the positions plain. 



Labradorite in Beans Purchase. Mr. G. N. Merrill, of Jackson, informs 

 rae that he has seen labradorite in rock masses upon Thompson's brook, 

 on the east side of Ellis river, in Bean's Purchase. I understand it is 

 situated on the west slope of Wildcat mountain, some three or four miles 

 back from the Ellis river. It is in the midst of the Montalban series, like 

 that on Mt. Washington river; but we have no facts in respect to the 

 position of either the labradorite or gneissic strata. 



