Winchell.] "^ [March 5, 



ancient continental sliores.i'° During the periods wliicli followed the Gene- 

 see epoch, the time was approaching when the agitations of the terres- 

 trial crust should culminate in the spread of thousands of square miles of 

 coarse debris over the bottom of the continental lagoon of North America; 

 the materials of the great Carboniferous Conglomerate. In the progress 

 of the gathering convulsion, the movement of the waters had attained 

 such a degree of violence during the period of the Portage and Chemung 

 as to give rise to the formation of flags and sandstones within the limits 

 of the State of New York, while yet the quieter waters which rested over 

 Michigan and Ohio were precipitating only the materials of shales , and 

 the regions further west were as destitute of mechanical sediments as of 

 the organic debris which give origin to limestones. In the following or 

 Marshall period, the disturbance of the terrestrial crust had attained such 

 a limit as to give distribution to the Catskill and so-called Chemung and 

 Carboniferous Conglomerates of New York, while in Ohio and Michigan, 

 it attained only such a degree of energy as had been witnessed in New 

 York during the preceding period, and resulted in the sandstones and 

 shales of the Waverly and Marshall series. Still further West the quiet 

 conditions of limestone-making continued to prevail. In the Knobstone 

 epoch following this, the agitation had extended still fu.rther West. While 

 3,000 feet of mechanical sediments were accumulating in Pennsylvania, 

 the conditions of sandstone accumulation had traveled towards the centre 

 of the American lagoon as far as Indiana, Kentucky and Tennessee, while 

 even yet, the state of quiet was sufficient in Illinois and west of the Mis- 

 sissippi to permit the existence of limestone making animals. The grand 

 agitations of the Millstone grit epoch followed, with the stiU later oscilla- 

 tions of the surface which conditioned the phenomenon of the Coal epoch, 

 terminated by the tremendous convulsions which gave birth to the moun- 

 tain barriers of the Atlantic border. But none of these events were felt 

 in the far West. Deep seas and limestone-forming operations — as Prof. 

 Hall has well shown^" continued to characterize the history of the inter- 

 ior of the continent while the coal marshes of Ohio and Pennsylvania were 

 heaved and tossed in the titaiiic pastimes of geological forces. 



This sketch of the succession of geological events shows that the parallel- 

 ism which I have traced is in strict harmony with the method of later Pale- 

 ontological Time ; and instead of suggesting abrupt disappearances and 

 incongruous synchronisms, is the only marshalling of the American strata 

 which keeps perfect time with the grand march of geological events. 



"» There is a priori evidence against tlie continuity of the Chemung and Waverly. Arenaceous 

 sediments, from the circumstances and conditions of their origin, must Ije limited in extent, at least 

 in one direction. We should therefore expect the Chemung to grow finer and to lose its physical 

 identity in its western prolongation ; and, if a sandstone recurs at the West, the immediate pre- 

 sum.ption arises that it is a phenomenon of changed continental conditions, characterizing another 

 geological period. Compare Hall; Foster and Whitney's Rep. 11, p. 2S7. 



"1 Keport on the Ueol. and Pal. Mex. Boundary Surv. p- 124 ; Iowa (leol. Kep. p. 137— 1-H. 



