ABSTRACTS OF PAPERS ^ 127 



PRESENTAT10:N^ of papers on paleontology and STRATIGRAPHY 



The first paper on the progTam, dealing with the stratigraph}' and 

 paleontology of the Paleozoic rocks on the Piedmont plateau, was illus- 

 trated by lantern slides and was discussed by Messrs. Grabau and Mer- 

 riam, A¥ith replies by the author. 



PALEOZOIC DEPOSITS AND FOSSILS ON THE PIEDMONT OF MAUYLAND AND 



VIRGIXIA 



BY E. S. BASSLER 



(Abstract) 



The western part of the Piedmont plateau in Maryland and Virginia contains 

 areas of early Paleozoic limestone infolded in the Precambrian crystallines and 

 overlaid in part by the Triassic (Newark) series. These limestones outcrop at 

 one point next to the early Cambrian Harpers shale, and it has hitherto been 

 believed that they represented the Shenandoah limestones of the Appalachian 

 Valley, comprising strata from early Cambrian to Middle Ordovician time. 

 Detailed mapping of this area and the discovery of fossils has shown that this 

 Piedmont limestone consists of a lower massive limestone division with Lower 

 Beekmantown fossils separated by a well marked disconformity from an upper 

 thin bedded dark-blue limestone With a Chazyan fauna. The Lower Beekman- 

 town division can be correlated directly with strata in the Appalachian Valley, 

 but the Chazyan portion has no representation there. 



There was then presented a study of an interesting problem in Devo- 

 nian stratigraphy by the author, illustrated with diagrams, which brought 

 forth discussion from several miembers of the Society. 



SIGNIFICANCE OF THE SHERBURNE BAR IN THE UPPER DEVONIC 

 STRATIGRAPHY 



BY AMADEUS W. GRABAU 



(Abstract) 



The original Sherburne sandstone of Vanuxem formed a bar which extended 

 from the old-land of Atlantica on the north to the mouth of the Devonic Rom- 

 ney River on the south. During its maximum development, shortly after the 

 close of the Hamilton period, it was about ten miles wide and formed an effec- 

 tive barrier between the Atlantic region which carried the typical Hamilton 

 fauna and western New York and the region beyond. In this area a renniant 

 of the Hamilton fauna, cut off from intercrossing with the main stock, de- 

 veloped into the early Ithaca, or Ipwer Portage fauna, to which were ndded 

 migrants from the Traverse survivors of the west. Meanwhile the pure llamil 

 ton, or Tropidoleptus. fauna continued in the embayment east of the bar, ro 

 maining in constant communication with the center of distribution of this 

 fauna in the Atlantic. In the Far West the Naples fauna made its ontraiice. 



