coos AND ESSEX DISTRICT. 39 



Mr. James Richardson describes the rocks in the area between the Chau- 

 diere and the Temiscouata road, the boundary on the north-west being 

 the St. Lawrence, and on the south-east the province Kne. At St. Denis 

 he finds fossils of the lower division of the Potsdam. This corresponds 

 to the Georgia group of Vermont. Then follows what he regards as the 

 middle and upper division of the Potsdam ; then there is a fault, south 

 of which he finds the Sillery sandstone; and then, south of what he 

 makes an anticlinal, follow, resting on these metamorphic Quebec rocks, 

 the slates so well developed in the Chaudiere from St. Francis to Lake 

 Megantic. These last, according to Richardson, overlie the Lauzon. 



The metamorphic Quebec rock of Logan, now recognized as Huronian, 

 occurs in New Hampshire east of the rocks just mentioned, except that 

 there intervene bands of schist and gneiss containing andalusite and 

 staurolite, which may be more recent. These Huronian rocks, as they 

 occur in New Hampshire, may be described as follows : Green chloritic 

 rocks, in which the lines of stratification are obscure. These often con- 

 tain scales of chlorite. Variable greenish feldspathic sandstones, with 

 intercalated bands of siliceous limestone. In these sandstones there are 

 sometimes developed large crystals of feldspar, and elsewhere they con- 

 tain an abundance of hornblende, and frequently epidote, argillaceous 

 quartzite, green chloritic schists, stratified diorites, serpentine, and some- 

 times soapstone. The rocks immediately underlying the Calciferous mica 

 schists, which contain staurolite, andalusite, and allied minerals, we regard 

 as a part of the Coos group. Looking over the large area occupied by 

 both groups of rocks just described, we find that, overlying these and 

 occupying beds in this rock, there are several small areas of fossiliferous 

 rock, which are generally referred to the Lower Helderberg. Beginning 

 on the south, we have the fossiliferous band at Bernardston, Mass., with 

 its immense crinoid stems ; and, going north, at Littleton, N. H., we have 

 a limestone, with brachiopods, corals, crinoid stems, etc. At Lake Mem- 

 phremagog, on the border of the Calciferous, we have a similar band, and 

 at Dudswell, on Famine river, and other localities in Quebec province, we 

 find fossils of a similar character. In Flagstaff, Me., there is Helderberg 

 limestone, associated with rocks very similar to those found at Littleton, 

 N. H. Sir Wm. E. Logan regarded the Calciferous mica schist as Upper 

 Silurian, from the fact that the fossiliferous bands were so associated with 



