1913.] NATURAL SCIENCES OF PHILADELPHIA. 123 



such a view of the orighi of the bulk of the Triassic/^ Russell's 

 ''attractive and very possible hypothesis" of glaciation of the 

 Appalachian Mountains in that period has been practically forgotten. 

 It is the writer's belief, however, that "the character and distribu- 

 tion of the debris" forming the conglomerate beds under discussion 

 constitutes a verj^ good argument for its revival. 



That the pebbles and boulders were carried down into the Triassic 

 basin along certain definite channels is clearly indicated by the 

 shapes and positions of the conglomerate masses. Something, in 

 fact, can be made out as to the possible routes along which they 

 came. In this region at present the position of streams is controlled 

 to a certain extent by fault or joint systems. Since most of these 

 structural features are, however, evidently pre-Triassic, it is reason- 

 able to suppose that similar depressions existed there then and 

 became at times river channels. It can readily be seen on the map 

 that stream routes (marked by heavj^ dotted lines) do actually 

 strike the edge of the Triassic belt at or near the centers of the several 

 conglomerate masses, although of course changes of geography 

 since that period have altered the actual direction of the drainage 

 and superficial features. But the boulders in the conglomerates 

 are too large to have been carried by any streams flowing in these 

 channels at the present day and, indeed, as shown above, torrential 

 alluvial-fan origin is improbable. Russell's arguments against a direct 

 glacial origin being also valid, as far as all later observations go, 

 apparently only one possible mode of formation remains — trans- 

 portation by floating ice. 



Evidence favoring this view has been unexpectedly obtained in 

 the course of field work to the southwest of HellertowTi. The 

 Saucon Valley, a broad limestone plain which lies to the north of 

 the Triassic highland here, contains extensive deposits of what is 

 regarded as extra-morainic drift. It is believed that in late Quater- 

 nary glacial times the Lehigh River was temporarily dammed back 

 and formed a lake— locally called Lake Packer — whose surface 

 reached a height of 450 feet above tide, and which therefore spread 

 over much of Saucon Valley. Floating ice, breaking off from the 

 front of the great glacier, which extended on the Lehigh only to 

 White Haven, over fifty miles north of the present region, came down 

 stream, and some of it was carried by currents around into the 

 Saucon Valley Bay. As this ice gradually melted, numerous well- 



1- Cf. Lull, R. S., The Life of the Connecticut Trias, Amer. Jour. ScL, [4] XXXIII, 

 pp. 397-422, 1912, and the writer, Proc. Acad. Nat. Sci. Phila., 1912, pp. 371, 372. 



