228 J. Barrell — Upper Devonian Delta of the 



have extended beyond the present outcrops of their strata in 

 cases where the strata do not show internal evidence of the 

 proximity of a shore. On the other side of the argument, 

 although several masses of Lower Devonian age have thus 

 been preserved, none from the Upper Devonian has been 

 found. 



As similar testimony from another region, attention should 

 be called to the observations by Weller regarding the acciden- 

 tal preservation of a late Upper Devonian fauna in a fissure in 

 Silurian limestone near Chicago."" The nearest known Upper 

 Devonian strata occur 80 miles north and 130 miles west, but 

 even these beds appear to be somewhat older than the filling 

 of the fissure. The nearest place where Devonian strata form 

 the surface rock is probably under the heavy drift in north- 

 western Indiana. 



The Laurentian province was not involved in the vigorous 

 Upper Devonian mountain-making. Nor were these move- 

 ments marked by a wide withdrawal of seas from the more 

 quiet areas. Over such a region as that north of the St. Law- 

 rence valley shallow ocean water may have spread consequently 

 to a considerable distance. The strata, if they once existed, 

 have not been preserved by infolding nor by the downfaulting 

 which has protected remnants of some older Paleozoic forma- 

 tions within the Laurentian Plateau ; but such facts as those 

 cited show the possibility of the extension of shallow seas over 

 lands not subjected at the time to uplift ; and the later oblit- 

 eration of the sedimentary evidence upon regional elevation 

 followed by prolonged erosion. 



Professor Schuchert has pointed out to the writer, however, 

 that in the late Silurian the bay faunas of that time appear to 

 have been distinct from each other in New York and in the 

 Maritime Provinces. Of the latter region, however, but little 

 is known. A more declaredly marine facies appears further- 

 more in the Great Yalley Province of the Appalachians, suggest- 

 ing that the sea lay in that direction, a strait opening either 

 across New' Jersey or farther south ; but that no connection is 

 probable through the Saint Lawrence Valley. He has called 

 attention, however, to the Monroe problem of Grabau, the 

 strata near Detroit holding a fauna seemingly unrelated to the 

 other faunas of the period, and which may have entered from 

 the north. Although Schuchert and the writer are agreed as 

 to the general improbability of waterways crossing the trends 

 of mountain structures in times of orogenic activity, there 

 seems to be no incompatibility of their crossing after long 

 periods of erosion, and due to broad warpings or local down- 

 sinking. Such relations are especially possible when they 



*Jom\ Geol., vii, 483-488, 1899. 



