l6 STRATIGRAPHICAL GEOLOGY, 



The upper members of Anticosti island, amounting to more than looo 

 feet, appear to range through the whole of the Upper Silurian. The 

 principal development of the Upper Silurian is therefore in the neigh- 

 borhood of the St. Lawrence gulf, in the same district with deep sea 

 deposits of the preceding system. They may connect with the north- 

 eastern extension of the more eastern ranges of the same age. 



Let us now note the character of the Cambrian and Silurian formations 

 of the eastern or Atlantic. We find, first, a series of slates rather older 

 than the Lower Potsdam, characterized by the presence of Paradoxides. 

 At Braintree, Mass., are clay slates of this age several hundred feet thick, 

 associated with great thicknesses of grits and conglomerates, shown upon 

 Section i of this chapter. Related rocks are abundant along the New 

 Hampshire and Maine coasts. Near St. John, N. B., they have been 

 studied carefully, and consist of slates and grits certainly 2000 feet in 

 thickness, with the fossils Conocoryphe, Agnostus, EUipsoccpJiahis, Micro- 

 discus, and Paradoxides. In south-east Newfoundland the last of these 

 genera has also been found; also, 6000 feet of the Lower Potsdam or 

 Olenellus formation. \\\ Nova Scotia the auriferous rocks are latterly 

 referred to the Potsdam series, or the Lingula flags of Great Britain. 

 Their thickness is very great, probably exceeding that of the Potsdam 

 rocks below Quebec, in the St. Lawrence valley. 



The next series that seems to belong to the Lower Silurian is the clay 

 slate of central Maine. Portions of this near Waterville abound in Ncrcitcs 

 and related impressions of rather uncertain affinities. Section 3 of this 

 chapter crosses them, and they must be several thousand feet thick. 

 There are numerous smaller areas of similar slates, without fossils, in 

 other parts of the New England area. A measurement of one of them, 

 in Lyman, gives a thickness, certainly, of 1500 feet. 



In the west part of New Brunswick, passing into Maine, is the Masca- 

 rciic scries of Bailey and Matthew, which evidently belongs to some part 

 of the Silurian system. A carefully measured section gives nearly 2000 

 feet, arranged in five divisions. The rocks are feldsi^athic shales, felsites, 

 flags, sandstones, and conglomerates, much resembling the Huronian. 

 The fossils are Lingula, Modiolopsis, and Loxoiicvta. Similar rocks make 

 their appearance in limited patches off the coast of Hancock and Wash- 

 ington counties, in Maine. A detailed section of them at Machiasport is 



