PALEOZOIC TERRANES IN THE CONNECTICUT VALLEY. 511 



separated in obedience to the principle that similar rocks belonged to the same 

 age, while dissimilar rocks belonged to different ages. It now seems probable that 

 an argillite may nnder certain conditions develop staurolite, andalusite, garnet and 

 other minerals. This newer argillite enters Vermont from Massachusetts in Guil- 

 ford and Vernon, and may be traced northerly to the southern part of Coos county, 

 New Hampshire, and perhaps farther. The most important feature of delineation 

 is the connection of the Guilford slate with a part of the Coos group in Charlestown, 

 New Hampshire, which in turn joins a band of slate reaching to the north line of 

 the southwest sheet of the general map, passing through Claremont. I find it is 

 continuous still farther, at the expense of the Coos group, through Cornish, Han- 

 over and Lyme, New Hampshire. It is probable that the synclinal area of slate in 

 Bath and Lyman, New Hampshire, retains the same structure into Littleton and 

 Dalton, constituting the principal portion of the Blueberry mountain range. None 

 of this carries staurolite, but the segment carrying this mineral very prominently 

 lies upon the east side of the Lower Ammonoosuc river in Lisbon, and is entirely 

 separated from the former. For the tracing out of the slates in Charlestown I am 

 indebted to Mr. G. D. Hull. 



Hornblende-schist 



In the neighborhood of Hanover this rock occurs in igneous bunches, varying in 

 size from a peck-measure to a mass ten miles long. Planes of foliation traverse 

 these masses with a quite constant hiclination of fifty degrees northwesterly. On 

 the northwest side of the principal range the schist comes successively in contact 

 with mica-schist, hydromica-schist, argillite and chlorite-schist, all of which have 

 been altered through heat into vitrified and indurated rocks, usually richer in silica 

 than when unaltered. On the southeast side the adjacent rock is invariably mica- 

 schist somewhat indurated. It is supposed the foliation is induced by pressure 

 exerted at right angles to the dipping planes, but as there is no apparent material 

 above the hornblende to act as a weight, it is conceivable that a great mass of mica- 

 schist once occupied the place and has since been removed by erosion. In the 

 smaller bunches both walls are present and their agency is apparent; hence the 

 present attitude of the igneous hornblende is like that of the modern laccolite w^here 

 the cap has been worn away. 



Protogene 



The areas of protogene gneiss prove to be eruptive because they contain abundant 

 inclusions of mica-schist, the inclosing rock. They are the Hanover-Lebanon and 

 the North Lisbon end of the areas, colored Bethlehem gneiss upon the map. They 

 were called Archean in the report with the approval of Professor J. D. Dana for the 

 one and of Dr T. Sterry Hunt for the other. The foliated planes are obscure. 



Paleontology 



The removal to the igneous category of the foliated hornblende-schists, diorites, 

 diabases and two kinds of protogene, most of which had been classed with the Hu- 

 ronian, will simplify the determination of the age and relations of the schists asso- 

 ciated with the fossiliferous terranes in Lisbon and Littleton. Niagara fossils, such 

 as Holy sites, Pentameriis nysius and Dalmania limulurus, occur there upon sediments 



