LOWEK SILURIAN. 217 



at Gaspe, there was apparent quiet north of Gaspe in the St. Law- 

 rence Gulf; or, if interruptions occurred, through the earthquake 

 waves that must at intervals have swept destructively up the bays and 

 over the land, still there was no profound disturbance. This is proved 

 bv the fact already mentioned, that the great limestone formation of 

 Anticosti, which was begun in the lower Silurian, continued its un- 

 broken progress through the whole prolonged era of revolution, and 

 afterward far into the Upper Silurian era. 



"What happened in Nova Scotia during this disturbance is not yet 

 definitely known. 



The making of the Appalachians from New Jersey southwestward 

 took place later, and mainly at the close of the Paleozoic. But, at 

 this same epoch, according to Safford, Newberry, and Orton, the region 

 from Lake Erie over Cincinnati into Tennessee, where rocks of the 

 Cincinnati and Trenton eras are exposed to view, was lifted into a 

 geanticlinal (p. 730), so as to stand for the remainder of the Silurian 

 age and part of the Devonian as an island in the continental seas. 

 The axis of the uplifted region is parallel to that of the Appalachians. 

 That this was the time of the uplift is proved by the absence of Up- 

 per Silurian and Lower Devonian beds over the region, these for- 

 mations thinning out toward the axis ; and, in Tennessee, as SafFord 

 states, by the Devonian black slate resting directly on the Lower Silu- 

 rian beds. 



This epoch of revolution closing the Lower Silurian was followed, 

 if not attended, by the formation of a coarse conglomerate along the 

 Appalachian region, which is described beyond. There was also, as 

 has been remarked, an extensive extermination of the living species, 

 over the continental seas. 



In Europe, there was also a period of disturbance at the close of the 

 Lower Silurian ; but the destruction of life was less complete than 

 over central North America, and corresponds nearly with that in the 

 eastern basin about the Gulf of St. Lawrence. 



There is evidence of unconformability between the Upper and 

 Lower Silurian in many parts of England ; and the elevation of the 

 Westmoreland Hills, as first ascertained by Prof. Sedgwick, has been 

 referred to this epoch; so, also, that of the mountains in North Wales, 

 and hills in Cornwall, and the range of southern Scotland, from St. 

 Abb's Head, on the east coast, to the Mull of Galloway. Elie de 

 Beaumont refers to this era the elevation of the Hundsruck Chain 

 (now about 3,000 feet high) and other ridges in Nassau. The changes 

 of the period are supposed to have been attended in England by meta- 

 morphic action, in which gneiss and clay slates were made out of the 

 Lower Silurian deposits. 



