366 



PROCEEDINGS OF THE ACADEMY OF [July, 



SILICIFIED WOOD FROM THE TRIASSIC OF PENNSYLVANIA. 

 BY EDGAR T. WHERRY, PH.D. 1 



The occurrence of silicified wood in the Triassic or "Newark" 

 rocks of the eastern United States was first observed in the Richmond 

 Basin. Virginia, by Thomas Nuttall in 182 1, 2 and it was shortly 

 afterward discovered in North Carolina 3 and in Connecticut, 4 but 

 its presence in Pennsylvania does not appear to be mentioned in the 

 literature. 5 



The inhabitants of southern Bucks and northern Chester and 

 Lancaster Counties have long recognized the character of specimens 

 of it plowed up in their fields, but its scientific interest was first 

 realized by Mr. John F. Vanartsdalen.of Holland, Bucks County,about 

 1890, who brought it to the attention of the writer several years 

 later. The western Lancaster County occurrences were discovered 

 independently by Professor H. Justin Roddy, of the Millersville 

 State Normal School. Subsequent search has greatly increased 

 the number of localities, so that it is now known to occur at short 

 intervals along the strike of the Triassic rocks, near their base — the 

 southern edge of the belt, since the clip is for the most part gently 

 northward — from the Delaware River to beyond the Susquehanna, 

 a distance of over 100 miles. These relations are well brought out 

 in the accompanying sketch map and geographical table. 



Table I. Localities of Silicified Wood. 



B. Bucks County. 



1. Roelofs: Farm of George W. DeCoursey, \ mile southeast of 



the station. 



2. Woodbourne: On several farms 1| miles north of the station. 



1 This paper, the fourth of the writer's studies on the Triassic, was presented 

 in preliminary form at the meeting of the Academy in association with the 

 Mineralogical and Geological Section on May 18, 1909, but publication was 

 deferred until opportunity for completing the work could be obtained, the final 

 results being announced at the similar meeting on May 21, 1912. 



2 Observations on the Geological Structure of the Valley of the Mississippi, 

 [etc.], Jour. An,,]. Nat. Sci. Phila., II, i, p. 37. 



Olmsted, D. Descriptive Catalogue of Rocks and Minerals Collected in 

 North Carolina, Amer. Jour. Sci., [1], V, p. 261, 1822. 



4 Hitchcock, E. Miscellaneous Notices of Mineral Localities, with Geological 

 Remarks, Amer. Jour. Sci. [1], XIV, p. 228, 1828. 



5 Compare, however, Prof. O. C. S. Carter: A Ferruginised Tree, Jour. 

 Franklin Inst., CXI.!, pp. 227-229, 189G, which perhaps refers to similar material. 



