GEOLOGY OF THE WHITE MOUNTAIN DISTRICT. 259 



4. HiLvonian. As at present defined, the Iluronian barely touches the 

 edge of the White Mountains in Lancaster and Northumberland. On the 

 east side of the Stark porjDhyry mountains exists a large development of 

 hydro-mica, argillo-micaceous, and hornblende schists, with quartzites, 

 which seems better allied to the Huronian than to any other group. 

 The area on the map (PI. V) is made to begin in Stark and Milan, ex- 

 tend north-easterly through Dummer to Errol, and then diminish to an 

 extremely narrow band passing north-westerly to join a range of upper 

 Huronian in Dixville and the divisions of Carlisle's Grant. The rocks 

 agree with much of the area mapped as Huronian in Columbia and Strat- 

 ford. 



Closely connected with this area in character are the Jackson quartz- 

 ites, the rather nondescript schists west and north of Umbagog lake, the 

 Merrimack group of the southern part of the state, and, more remotely, 

 the andalusite slate group of the White Mountains and elsewhere. The 

 first will probably be colored as Huronian upon the map ; the others will 

 be distinguished from it for the present. 



5. Merrimack Schists. This formation will be described in succeeding 

 chapters, as it is best developed in the south part of the state. It is 

 probably the equivalent of the eastern band of Huronian in Stark and 

 Dummer. Further study of it may afford us better views of its proper 

 character. 



G. Andalusite Slate Group. In Massachusetts this group is found as- 

 sociated with the preceding in such a way as to suggest its later age. In 

 Michigan a similar rock is given as the uppermost member of the Huro- 

 nian. The mineral chloritoid found in the specimen from Willey brook 

 by Mr. Hawes (p. 233) is suggestive of the Huronian. The range run- 

 ning through Mts. Moosilauke and Carr preserves a closer resemblance 

 to the Montalban andalusite or fibrolite schists than those in the White 

 Mountains. In our preliminary reports this has been ranked with the 

 Coos group along Connecticut river, which it resembles chiefly through 

 the similarity of the minerals andalusite and staurolite. The associated 

 rocks are different in the two areas. I desire to call the attention of 

 future explorers to the possibility of finding more of this formation upon 

 the east spur of Mt. Madison and Pine mountain. 



A possible clue to the age of this formation is afforded by its htho- 



