Remarks on the Taconio System. 279 



cessively into view, and giving their present steep inclination 

 eastwards. Simultaneously there was a transverse fractnre, in an 

 east and west direction, interrupting the longitudinal at various 

 and irregular distances, and at the same time pushing the north 

 end of the interrupted strata to the west of and by the south 

 end, thus giving the mountains their echelon arrangements, as 

 has been stated. In the wider valleys, isolated fractures and 

 elevations sometimes took place. 



Subsequently in the order of time there was a depression of 

 the western edge of the system ; the upturned edges were 

 abraded, and furrowed into deep chasms, to form material for 

 the nascent Silurian, and into these furrows and sometimes 

 mighty chasms, as well as on the basset edges of the Taconic, 

 the Silurian was laid down. Then followed another uprising, 

 leaving the Silurian dryland, while the Devonian was being 

 formed. Again another oscillation while the Carboniferous was 

 being deposited. These various elevations and depressions we 

 suppose to have been so gentle in their action, as not materially 

 to disturb these rocks. At the close of the Carboniferous age, 

 when the Apalachian system of elevation was exerted upon 

 this continent, these rocks were subjected to further dis- 

 turbances. The east and west dislocations were further ex- 

 tended, the already hardened material was crushed and com- 

 minuted, and the whole of this system underwent so marked a 

 change, that many observers consider the Apalachian elevation 

 the only one exerted upon these rocks. But no one system of 

 elevation can satisfactorily explain all the phenomena of this 

 interesting group of mountain strata. 



These rocks had already been wasted by ocean forces, to yield 

 material for the Silurian, and, perhaps, all the succeeding for- 

 mations, when they, in common with all the eastern portion of 

 our continent, were depressed beneath the seas, and subjected 

 to all the varied operations of the drift forces, whatever they 

 may have been. 



On emerging from the waters for the last time, they were 



MAY, I860. 1 9 Ann. Lyc, Nat. Hist. Vol. VII. 



