168 C. SCHUCHERT THE XORTH AMERICAX GEOSYXCLIXES 



may remain as dry lands or may sink into the depths of the oceans, as in 

 the Butch East Indies. 



Finally, we must note the greatest nphowings of the continents that 

 result from epeirogenic movements. These were first defined by Dana 

 and Gilbert as the very broad and flat archings that appear long after 

 folded mountains are made, the uplift affecting at the same time both 

 synclinoria and anticlinoria and even parts of the far inland neutral 

 regions. Such are the greater Appalachian uplift extending from the 

 Atlantic Ocean to the Mississippi Valley, and the far vaster and higher 

 Eocky Mountain arch extending from Kansas and Xebraska to the Pacific 

 Ocean. The latter came into existence after the Miocene, and its crest is 

 between 5,000 and 7,000 feet above sealevel, on the top of which are 

 situated the protuberant remainders of the previously made spiclinoria 

 and anticlinoria. 



Peoterozoic Geosyjstclixes 



(See Map, Figure 1) 



When it became apparent that the Cordilleran and Appalachian geo- 

 synclines were in existence in earliest Cambrian time, it was thought 

 desirable to learn when they originated. The writer therefore took Yan 

 Hise's correlation papers for the Archean and Algonkian-^ and plotted 

 on a map of Xorth America the late Proterozoic deposits (Keweenawan 

 and Animikie). Copies of this map were then sent for criticism to the 

 following geologists in this country and Canada : Arthur Keith, Eleanora 

 Bliss Knopf, Anna I. Jonas, Edward Sampson, D. F. Hewett, F. J. 

 Alcock, C. K. Leith, and J. J. O'Xeill. The map (figure 1) here pre- 

 sented is the result of this assistance, for which the writer is very thank- 

 ful. The shorelines as plotted must, of course, be conjectural, and all 

 that is really valuable is the general trends and positions of the four sea- 

 ways : (1) Appalachian, (2) Cordilleran, (3) Ontarian, and (-t) the 

 greater Arctic sea. The southern opening of the Apjialachian geosyncline 

 and the southern and northern ones of the Cordilleran troughs are also 

 highly conjectural. It may be that Daly's northern continuation of the 

 latter waterway into the Arctic Ocean^^ is more correct than that shown 

 in figure 1 of this address. 



The Cordilleran geosyncline is the longest enduring trough and came 

 into existence earlv in the Proterozoic. Durino- this era there was de- 



-1 C. R. Van Hise : Correlation papers — Archean and Algoulcian. U. S. Geol. Survey, 

 Bull. 86. 1892. 



--It. A. Daly: Geology of the North American Cordillera at the- forty-ninth parallel. 

 Geol. "Survey Canada. Mem. 38. 1013, p. 202. 



