1893.] NEW YORK ACADEMY OF SCIENCES. 73 



strayed thither. But the past summer, in conuection with the 

 summer-school work of our Geological Department, two of our 

 students, Messrs, Ries and ;Fennor, went, under the writer's 

 direction, to the quarry, and prospected the neighborhood for 

 norite. They were successful, and found the outcrop in the 

 midst of the Archaean crystallines. 



The general geological relations are well shown on the larger 

 map by C. E. Hall (Sheet II. of Report C 6, Penn. Geol. Surv.), 

 and on this the accomjDanyiug small map has been based. The 

 entire area was, however, covered by Ries and Fennor, and on 

 their collections the rock determinations are based. As is shown 

 on the large map the Archseau rocks just touch the southwest 

 corner of Bucks County, covering a township or two. They are 

 of both massive and gneissic habit, and are collectively summar- 

 ized by Hall as granitic and syenitic rocks. Ries and Fennor col- 

 lected some green schist or amphibolite in square F2 of the small 

 map. The general outcrop of this Archiean exposure forms an east 

 and west belt, that at the quarry is about tw'o miles across. 

 The limestone outcrop is found in it at E2 and E3. It has 

 always been a puzzle, because, as stated in Report C6, p. 59, it 

 is the onl}' exposure of limestone that occurs in this Archfean 

 belt. South of the xlrchaan belt lies the Potsdam quartzite, 

 which, after a short distance, is succeeded by the Manayunk 

 schists. North of the granitic belt there is the Triassic sand- 

 stone with a conglomeratic streak along the contact. 



Van Artsdalen's quarry is one of the best known and most 

 prolific of the mineral localities near Philadelphia, aud it 

 frequently appears in the lists which have been prepared. In 

 Geuth's Report on the Mineralogy of Pennsylvania (Report B 

 of the Geol. Survey) the following species are recorded, the 

 number of the page being given after each : molybdenite, 

 p. 10 ; pyrrhotite, p. 17 ; pyrite, p. 20 ; blue quartz, p. 58 ; 

 wollastouite, p. 64 ; pyroxene, p. 65 ; garnet, p. 74 ; zircon, 

 p. 76 ; phlogopite, p. 82 ; muscovite, p. 85 ; weriierite, p. 86 ; 

 feldspar, p. 89 ; orthoclase, p. 94 ; titanite, p. 103 ; apatite, 

 p. 109 ; gypsum, p. 148. In Report BB, p. 225, an analysis of 

 orthoclase is recorded. T. D. Rand, in his Notes on the Feld- 

 spars, etc., of Philadelphia and Vicinity (Proc. Phila. Acad, 

 Nat. ScL, 1872), mentions orthoclase, aud J. Eyerman in his 

 Mineralogy of Peunsylvania, p. 22, refers to the same material. 

 It has special interest on account of its chatoyant lustre. The 

 notes on the mineral localities near Philadelphia, by Messrs. 

 Rand, Jefferis, and Cardoza, in the Proc, of the Phila. Acad,, 

 ^1892, p. 182, give another list which mentions in addition to 

 those above quoted from Genth, salite, fassaite, aud coccolite. 



