IX THE DEGRADATION OF THE LITHOSPHERE. 377 



vance of chemical weathering. In this case the destruction and 

 degradation would follow upon the previous history of the region. 



The disturbances of the Appalachian Revolution had brought 

 about a condition in the rock masses involving both folding and 

 fracturing. During the closing stages of the Pennsylvanian, and 

 most probably for some time after the close of this time proper 

 there were conditions of non-equilibrium, the position of the sea 

 level was not probably fixed but was in an oscillatory condition. 

 This condition of the lithosphere in that portion of the North Amer- 

 ican continent now known as the Atlantic border would involve a 

 system of rock structures in which by successions of strains, folds, 

 shiftings of sea level, the elastic resistance had been destroyed. 

 The rock masses would pass by variations of uplift and erosion into 

 the zone of fracture as well as the zone of folding. The Newark 

 time would appear then as a time in which the strains of the previous 

 time era had developed a great mass of fractured and jointed rock 

 as the outer portion of the lithosphere. 



The physical conditions of the continent east of the present Ap- 

 palachian mountains were manifestly very different from those 

 west. What it was that induced the great degradational move- 

 ments to form the thick deposits of the Newark must be some- 

 what a matter of conjecture. That it was rapid is indicated by 

 the nature of the sediments, that it did not in large parts of the 

 area follow long periods of thick accumulation of a soil cap from 

 chemical weathering would also seem to be a legitimate conclusion 

 from the pronounced mechanical nature of the sediments, as the 

 granitic sandstones for example. 



The character of the early Pottsville sedimentation together with 

 the Newark series as described from its series along the eastern 

 states would however seem to call for an explanation based upon 

 the idea of a quick mechanical rock destruction and transportation 

 such as jointing would induce. The fracturing of the surface for- 

 mations of the lithosphere had probably already occurred, there 

 was needed the agent to separate and remove the segments small 

 and great due to this fracturing. This might have been just as it 

 is now in various portions of the earth due to steep surface drain- 

 age, glaciation or any one of the active means of transportation. 



