BASAL CONGLOMERATE IN PENNSYLVANIA 521 



the series and next to the dolomite is a dense, highly ferruginous, almost jaspery 

 quartzite. It is fi-equently brecciated and recemented by an abundant infiltration 

 of quartz, which may be either of a chalcedonic nature or distinctly crystalline. 

 The quartz frequently covers the broken surfaces and lines the walls of cavities in 

 its drusy form. This phase of the quartzite is well developed at Emaus. The de- 

 composed highly ferruginous quartzite of this horizon here, as well as at numerous 

 other localities in Lehigh and Northampton counties, carries percentages of iron 

 high enough to constitute a low grade ore, and it was formerly one of the important 

 iron bearing horizons of the region. No equivalent of the " York shales " * could 

 be found lying between the quartzite and the overlying dolomites. 



Summary 



The basal conglomerate or quartzite series, as it occurs along the northern margin 

 of the pre-Cambrian area in Northampton and Lehigh counties, presents in the 

 main the same lithological characters as its equivalent to the southwest in York 

 county, exce])t that the uppermost member in the former region is wanting in the 

 latter ; also when compared with the same beds to the northwest in northern New 

 Jersey there is a striking similarity. The failure of these beds to appear in the 

 intervening region along the Delaware river in Northampton county, particularly 

 in the immediate vicinity of Easton, is due to thrust faulting, by which the pre- 

 Cambrian gneisses have been forced up over the Cambrian dolomites. 



The basal quartzite series in Lehigh county begins at the base with a few feet of 

 coarse conglomerate, which fades over into the underlying pre-Cambrian gneisses 

 with no sharp line of demarcation. It is followed by a typical arkose, which at 

 times changes to dense bluish or grayish quartzite, having interstratified with it a 

 few feet of impure, fine grained quartzite containing scolithus. The uppermost 

 member of the series is a very fine grained, almost jaspery, frequently highly ferru- 

 ginous quartzite, which here constitutes one of the important iron bearing hori- 

 zons. ' The series is the northeastern extension of beds which, in York county, 

 have been called by Walcott the Hallam quartzite, and is the equivalent of the 

 Hardiston quartzite of Kummel and Weller in northern New Jersey. 



Remarks on the subject of the paper were made by Bailey Willis and 

 the author. 



First Vice-President S. F. Emmons was called to the chair and the 

 third paper was read, as follows : 



SANDSTONES OF THE OZARK REGION IN MISSOURI 

 BY C. F. MARBUT 



An abstract of this paper was published in Science, volume xvii, i)age 

 291. 



Remarks were made by Professor A. H. Perdue, a visitor. 



*Bull. U. S. Geol. Soc, no. 134, p. 14. 



