376 



PROCEEDINGS OF THE ACADEMY OF [July, 



A few words should be added concerning the nomenclature of the 

 America]) formations. The upper portion of the Newark was 

 divided by Mr. Lyman, as shown in the table, into three members: 

 the Lansdale, a soft red shale, followed by the Perkasie, described as 

 harder and darker in color, and the Pottstown, again soft and red. 

 The writer has not been able to recognize the validity of this sub- 

 division, as the Perkasie at its type locality, as well as at several 

 other places, contains various secondary minerals, such as quartz, 

 epidote, and stilbite and other zeolites, which are seen in microscopic 

 sections to fill the spaces between the grains, and are also often 

 crystallized out in crevices, showing it to be merely a metamorphosed 

 phase of the otherwise soft red sediments. It is therefore most 

 convenient to treat these three formations as a unit, for which the 

 name Brunswick, first applied to the New Jersey area, may well be 

 adopted. For the two lower formations the Pennsylvania names 

 have priority, but since the New Jersey ones have been rather widely 

 used it seems necessary to give both to insure against any mis- 

 understanding. 



While the earlier observers were inclined to consider the fossils 

 of the American Newark as equivalent to forms from the Rhsetic 

 of Europe — the transition stage between the Triassic and Jurassic 

 periods — the plants were shown by Stur 16 to match most closely 

 those of the German Lettenkohle or lower Keuper, and more recently 

 Dr. C. R. Eastman 17 has found the fish fauna to have its analogue 

 in that of the upper Muschelkalk and the lower Keuper of the 

 Alpine Province. In all of these discussions it has been taken for 

 granted that the Newark is a geologic and paleontologic unit; and 

 it must be admitted that little definite evidence to the contrary has 

 as yet been obtained; but it seems incredible that the enormous 

 thicknesses of beds developed here could all be represented by two or 

 three hundred feet of the foreign Triassic. Mr. Lyman's plea for the 

 more definite placing of fossil occurrences in the stratigraphic column 

 is therefore worthy of more attention than it has received, for it is 

 only by so doing that we can ever hope to learn the true relations 

 and equivalences of the beds. 



A geographical table of the more important fossil localities of 

 Pennsylvania, exclusive of those of silicified wood, which were given 



6 Die Lunzer-Lettenkohlen Flora in den "Older Mesozoic Beds of the Coal 

 Field of Eastern Virginia," Verh. KK. Geol. Reichsanst., 1888, pp. 203-217. 



7 Triassic Fishes of Connecticut, Bull. Conn. Geol. Nat. Hist. Surv., No. 18, 

 .pp. 23-25, 1911. 



