322 ROLLIN T. CHAM BERLIN 



to the east of the present Appalachians, more or less paralleling 

 that later system as it does the coast. This Ordovician system 

 may be regarded as a forerunner of the late Paleozoic Appalachians. 



The local stratigraphic details in various portions of this general 

 region, and the great extent of the emergence at this time are clearly 

 pictured in the time scale for eastern North America given by 

 Ulrich and Schu chert in their paper on Paleozoic seas and barriers 

 in eastern North America.^ It is the view of these authors that 

 the disturbance was felt first in the southern portion of the Appala- 

 chian region and progressed thence northeastward along the axis 

 of folding and westward toward the Mississippi basin, and so they 

 beHeve it was not quite synchronous throughout the entire region 

 affected. In the Lenoir basin (comprising the Athens and Knox- 

 ville troughs) the emergence followed the deposition of the Sevier 

 shale, while in the Mississippi basin they regard the main emergence 

 as having followed the Richmond, the time of the maximum uplift. 

 The movement appears to have commenced with several minor 

 pulsations in the closing stages of the Ordovician (Lorraine and 

 Richmond) which quickly led to the great Taconic revolution which 

 terminated the Ordovician, and which was one of the greatest 

 movements in North American Paleozoic history. According to 

 Ulrich and Schuchert, this revolution affected all North America, 

 there being perhaps land throughout from Richmond to Oneida 

 time. But the length of this land interval they beHeve cannot be 

 satisfactorily ascertained as there are no Mississippi basin sea 

 deposits by which its duration may be measured. 



It appears quite widely in the literature that the Cincinnati 

 Arch and Nashville Dome, in Ohio, Indiana, Kentucky, and Ten- 

 nessee, originated also at this time. The basis for this view has 

 been the widespread unconformity at the base of the Silurian. The 

 Clinton follows the Ordovician and contains in its basal member 

 rounded fragments of the Ordovician rocks^ which suggests that the 

 primary uphft of these domes may have been a feature of the 

 Ordovicide movement. Foerste, however, regards the evidence for 



' E. O. Ulrich and Charles Schuchert, "Paleozoic Seas and Barriers in Eastern 

 North America," Bull. LII, New York State Museum (1901), p. 658. 

 ^ Bailey Willis, op. cit., p. 232. 



