502 BRAINARD AND SEELY — THE < HiCIFEROUS FORMATION. 



great monoclinals where the Archean mass to the west of them has been bod- 

 ily raised, leaving these dipping principally to the east. ( tften, however, they 

 appear as though an immense earth wave coming from the east had broken 

 itself along the crest into great fragments, which, displaced and crunched 

 together, are lying in confusion, while another portion of the wave-mass has 

 been shoved up and over, bo that the younger rock may be adjacent to or 

 below the older. Near the flank of the Green mountains the disturbances 

 ami metamorphism have heeu so great that the sequence of the rocks is made 

 out with greal difficulty. 



Our work ha> Keen conducted chiefly on the islands and along the eastern 

 border of the lake, and the results of our investigations, so far as they per- 

 tain to the Calciferous formation, are here presented. 



The Formation in General. 



Definition. — The term Calciferous is a convenient one, and is used in the 

 sense in which it was applied by the early New York geologists — i. '., to 

 designate all the strata included between the Potsdam sandstone and the 

 ( lhazy limestone. 



Directly beneath the Calciferous, the Potsdam consists of magnesian lime- 

 stone and sandstone, the latter containing fragments of brachiopods related 

 to Lingvla. The overlying Chazy may he separated into three divisions, 

 which, numbering from below, may he designated as .1. B, and < '. The 

 first, .1. is characterized by the presence of abundant fossils; its Bponges, 

 corals, cystids, orthids, and gasteropods. B, the part of the Chazy best 

 known by authors, is characterized by M<i<-tnr><i magna, Strephochetus, and a 

 massive Stromatocerium. C has its dove-colored limestone with bands of 

 magnesian limestone, its many corals, and its Solenopora, Orthoceras, Caly- 

 mene, TUamus, and RhynchoneUa. Our work with the Chazy, which forma- 

 tion i- so largely developed in the Champlain valley, is now well advanced, 

 and we hope goon to he able to present the complete results of our study. 



The line- between the Potsdam and Calciferous and between the Calcifer- 

 ous ami Chazy are, ;ii this time, only provisional; later investigations must 



fix the exact boundaries. The lower line is drawn just ahove the foBSiliferoUB 



Potsdam; the bottom of the Beries is a drab magnesian limestone, resting 

 upon a vitreous sandstone; the higher, at the bottom of a sandstone which 

 i- a— iimed to he the base of .1 of the Chazy a Bandstone recognized by the 

 Canadian survey,' 1 which possibly corresponds with the St Peter sandstone 

 bo largely displayed in the central Btates of the west. 



Thickness, \'uriih/, and Faunal Wealth. — In our study of the Calciferous 

 formation we have been surprised at its development, at it- vast thickness, at 



li>K.v "f « uiado, 1863, p. i 



