372 E. O. ULRICli REVISION OF THE PALEOZOIC SYSTEMS 



clusivcly, as 1 think, by the character of the faunas found respectively in 

 the shales and in the limestones. Granting, for the sake of the argument, 

 that they are contemporaneous and that the shore was to the east of the 

 shale, we have the anomalous condition of a pelagic graptolite fauna 

 hugging the shore while the true sublittoral and shallow water fauna is 

 confined to assumed deeper waters farther out. Aside from the great 

 improbability of such a reversal of the normal condition, it is incon- 

 ceivable that the floating graptolites, which are not dependent. on either 

 the depth of the water or on the kind of bottom, should be so strictly 

 confined to the Normanskill shale that not even an occasional straggler 

 is to be found in the limestones. Now^, it seems impossible that these 

 graptolites should be entirely absent in the limestones only a few miles 

 to the west if the shale was laid down at the same time and in the same 

 basin. That the graptolites when they were carried into the continental 

 seas at all did extend as far westward as the sea of the time is suggested 

 by the occurrence of typical Utica species as far away from New York as 

 Cincinnati, Ohio, a locality very near the extreme western edge of the 

 Utica transgression. 



On such grounds I long ago reached the conclusion that the Norman- 

 skill represents a time when the more inland areas with Stones Eiver 

 limestones were emerged; and, as is brought out in a later part (see 

 page 555, the soundness of the opinion has since been proved by unques- 

 tionable stratigraphic evidence. Under this conception, of course, the 

 absence of the Normanskill graptolites except in the narrow Appalachian 

 troughs, to which the marine waters in southeastern North America are 

 supposed to have been confined at this time, is at once explained. And 

 as these restricted Normanskill channels were included in the synthetic 

 "late Black Eiver and early Trenton submergence" they may be added as 

 another distinct stage of the continental seas to the several stages already 

 described. 



In order that the theory of interruption of deposition being often due to 

 current scour might be fairly tested, I have selected the "transgression," 

 which by general consent is accepted as the greatest known in geological 

 history, hence the otie which ofi'ers conditions more favorable to the 

 efficient operation of transcontinental currents than any other transgres- 

 sion now recognized. If the theory fails in this case, as we have seen it 

 does, it seems certain that it must fail also in all the others. There is no 

 reasonable chance for a great transcontinental current in the Cambrian 

 transgression ; and even less in those of the Silurian and Devonian 

 periods. As for the Waverlyan and Tennessean transgressions, these did 

 not extend north of the United States. Hence great oceanic currents 



