C. D. Walcott — Cambrian Rocks of Pennsylvania. 471 



bia, and then on the western side of the river from Wrightsville 

 north to the quartzites. On the western side of the river the 

 section appeared to be unbroken from the Hellam hills to 

 Wrightsville, and to be as represented by Dr. Frazer* in his 

 section along the right bank of the Susquehanna. In this the 

 succession is from a quartzite (1) to shales (2) and to limestone 

 (3)," the latter in Wrightsville, at the Columbia bridge; the 

 sandy shales and argillites (2) pass conformably beneath the 

 massive limestone (3) which forms a deep synclinal fold before 

 being cut off to the south by a fault. 



The second section examined was JSTo. 2 of Dr. Frazer's, 

 extending from Emigsville south through Red Lyon station. f 

 In the description of this section ^ he refers the sandstone in 

 the railroad cut just north of Emigsville to the Triassic New 

 Red sandstone. At the northern end of the cut he noted a 

 fine-grained sandstone, dipping 15° west, north 52 degrees. 

 To the southward of this he describes a calcareous, sandy, pink 

 shale, dipping south 5°, east 20°. This is subjacent to 27 feet 

 of blue, finely laminated limestone, with white streaks, upon 

 which rests a red bed of calcareous conglomerate two feet thick : 

 this in turn is subjacent to a belt of reddish shaly sandstone, 

 nine feet in thickness, which is capped by 156 feet of arena- 

 ceous shales of a somewhat flaggy character. 



He says: "There would seem to be, therefore, an anticlinal 

 in the Triassic measures — the only instance of one recorded 

 within the limits of this district. The contact line of lime- 

 stone and Mesozoic sandstone lies within or just north of the 

 town of Emigsville. The first recorded dip in the older for- 

 mation when projected upon the line of section is 2,160 feet, 

 or a little more than a third of a mile from the last dip."§ I 

 mention the details of Dr. Frazer's section as it is the one 

 which led me to the determination of the stratigraphic position 

 in the geologic series of the Chiques quartzites and the York 

 shales | which are subjacent to the Lancaster limestone.^ 

 The fault betweeen the Paleozoic (Lower Cambrian) rocks and 

 the New Red sandstone of the Mesozoic occurs in the railroad 

 cut, at the point indicated in Dr. Frazer's section as the crest 



*Second Geol. Survey of Perm.. 18*76. Section 1, accompanying Report of 

 Progress in the district of York and Adams counties for 1874. 



fLoc. cit., Section 2. \ Loc. cifc., p. 88. § Loc. cit., p. S9. 



|[ The name York shale is proposed for the band of shales resting upon the 

 quartzites surrounding the Hellam hills. It is peculiarly well developed in York 

 county, and appears to be absent in many of the sections about South Mountain 

 and about the same series of quartzites in Lancaster county. 



■[[The term York limestone was* proposed by Dr. Frazer for this limestone ; but 

 as he states that it is a prolongation of the Lancaster limestone into York county, 

 and that it is more fully developed in Lancaster county, I think it best to retain 

 the term Lancaster limestone, as it is hardly necessary to call the same limestone 

 by two different names in adjoining counties. 



