144 On American Geological History, 



ing and dipping the land in many alternations, were premoni- 

 tions of the great peiiod of revolution, — so well elucidated, as 

 already observed, by the Professors Rogers, — when the Atlantic 

 border, from Labrador to Alabama, long in preparation, was at 

 last folded up into mountains, and the Silurian, Devonian, and 

 Carboniferous rocks were baked or crystallized. No such event ' 

 had happened since the revolution closing the Azoic Period. 

 From that time on, all the various beds of succeeding ages up to 

 the top of the Carboniferous had been laid down in horizontal 

 or nearly horizontal layers, over JSTew England as well as in the 

 west, — for the continent from New England westward, we have 

 reason to believe, was then nearly a plain, either above or below 

 the water ; there had been no disturbances except some minor 

 uplifts : the deposits, with small exceptions, were a single unbro- 

 ken record, untill this Appalachian revolution.* 



This epoch, although a time of vast disturbances, is more cor- 

 rectly contemplated as an epoch of the slow measured movement 

 of an agency of inconceivable power, pressing forward from the 

 ocean towards the northwest; for the rocks Avere folded up 

 without the chaotic destruction that sudden violence would have 

 been likely to produce. Its greatest force and its earliest begin- 

 ning was to the northeast. I have alluded to the disturbance 

 between the Upper and Lower Silurian beds of Gaspe, to the 

 north. Another epoch of disturbance, still more marked, pre- 

 ceded, according to Mr. Logan, the Carboniferous beds in those 

 northeastern regions ; and New England, while a witness to the 

 profound character and thoroughness of the Appalachian revo- 

 lution, attests also to the greater disturbance towards its northern 

 limits. Some of the Carboniferous strata were laid down in 

 Pthode Island as clay and sand and layers of vegetable debris : 

 they came forth from the Appalachian fires as we now have 

 them, the beds contorted, the coal layers a hard siliceous an- 

 thracite or even graphite in places, the argillaceous sands and 

 clays crystallized as talcose schist, or perhaps gneiss or syenite. 



These very coal-beds, so involved in the crystalline rocks, are 

 part of the proof that the crystallization of New England took 

 place after the Coal Era. Fossils in Maine, Vermont, Canada, 



* It is ui-ged by Prof. Hall and others that the carboniferous beds in the 

 west lie unconformably on the beds below. But the disturbance indicated 

 was not one of bold flexures or uplifts. 



