EXTENSION OF THE CHAZY INTO CANADA. 299 



Philipsburgh section corresponds well in fossils and in lithological features 

 to the Calciferous of the southern part of Lake Champlain. There is also 

 evidence that the upper portion of this section (Logan's 5 4, B 5 and C 1) 

 corresponds to the Lower Chazy and Middle Chazy. Logan's ^ 4 is described 

 as " black, slaty, thin-bedded, nodular limestone." In appearance it closely 

 resembles the slaty limestone of Valcour island, though it has here a much 

 greater thickness. B 5 consists of purer, dark-colored, more massive lime- 

 stones, not unlike those of the Orthis and crinoidal beds. The evidence from 

 fossils is incomplete, as the smaller forms are obscured by metamorphosis, 

 while but few species have been described by Billings ; but the Chazy genus 

 Eospongia occurs here, and the large specimens of Orthoceras and of Lituites 

 seen in the ledges appear identical with those seen in this horizon at Valcour 

 island. But the upper 50 feet of the Philipsburgh section undoubtedly be- 

 longs to the Middle Chazy, for it contains numerous specimens of Macliirea 

 magna. These are to be seen on the hill 80 rods north of the railway station 

 at St. Armand. Two miles south of the village of Bedford, the Maclurea 

 beds are again exposed, and have a thickness of about 150 feet (Logan's 

 C 1). In color, texture and massiveness, these beds are identical with those 

 seen in western Vermont, Avhere the rocks are partially metamorphosed. 

 There remains, however, a possible gap between the Maclurea beds of Stan- 

 bridge and the dove limestone of Highgate springs. If Logan's view of the 

 sequence of strata at Stanbridge is correct, there should be placed in this 

 gap about 3,000 feet of slate and limestone conglomerates. Whether fur- 

 ther investigation will sustain this opinion remains to be seen. 



Cornwall Section. — In the town of Cornwall, Vermont, seventy miles south 

 of Philipsburgh, there is an uplift in which all the Lower Silurian lime- 

 stones are exposed, except the basal portion of the Calciferous. The rocks 

 are even more altered by metamorphosis than at St. Armand, and the fossils 

 are obscure ; but several typical species have been identified, viz., Ophileta 

 complanata, Bathyuriis saffordi, Bathyurus angelini, Maclurea magna, and 

 Asaphus canalis. The measures that answer to the Chazy are as follows : 



A. Black, massive limestone, with frequent layers of tough, slaty 



matter, which, in weathered escarpments, protrudes in sharp 

 ridges; followed by lead-colored pure limestone in beds one 

 to three feet thick.* In all about .... 250 feet. 



B. Lead-colored, compact, massive limestone, containing Maclurea 



magna, . . . . . . . . 150 feet. 



C. Pure, dove-colored, fine-grained limestone, in beds one or two 



feet in thickness, interstratified with numerous beds of dolo- 

 mite, weathering buff, drab, or gray. Certain strata are 

 crowded with brachiopods, supposed to be Rhynchonella . 300 feet. 



Aggregate thickness ..... 700 feet. 



* The resemblance of these strata to those we coosider their equivalent at Philipsburgh is very 

 marked. 



