1885.] 40t) [Frazer. 



been poured out from a comparatively small vent. One of these may be 

 seen in Warrington and one in Monaghan townships. The chief constitu- 

 ents of this rock are pyroxene (or augite) and labradorite. Magnetic oxide 

 of iron is always, and apatite is very generally present. The trap in 

 Warrington is directly connected with the mass in and to the east of 

 Gettysburg, and is identical in composition with the so-called "Gettysburg 

 Granite."* The Triassic is represented by a medium tint of violet on 

 the map. 



Cainozoic. Of these, including the Quaternary and Recent, the only 

 representatives are the marl bed north of Dillsburg, (?) and the gravels, 

 fluviatile deposits, and Indian sculptures on the banks and islands of 

 the great river. Full descriptions and phototypes of these latter will be 

 found in Vol. CCC, 2d Geol. Surv. of Pa.'s publications. Though in strict 

 accordance with the determination of Prof. Cope, just given, it should be 

 represented perhaps as t3, which is a violet of very light tint. No rocks 

 answering to the description of the shell limestone or "Muschelkalk," 

 which constitutes the middle Trias of Germany and France, have been 

 found in Pennsylvania at least. Pending the establishment of a parallel- 

 ism, I have adopted the plan suggested by the International Geological 

 Congress, of coloring the entire area as if it were the middle member of 

 the formation. f 



Analyses of Ores, Rocks, Minerals, <fec. 

 Note 1. An analysis of a mica schist with imbedded crystals from half 

 a mile N. W. of Cully's station, Columbia and Port Deposit R. R., is 

 added here for comparison with that of the Beach-Bottom slate which fol- 

 lows : (No. 1705 in Survey's catalogue of specimens, CCC, p. 271.) 



P. C. 



Silica (Si0 2 ) 59.01 



Titanic oxide (Ti0 2 ) 1.34 



Phosphoric oxide (P 2 3 ) (traces) 



Alumina (A1 2 3 ) 17.02 



Iron sesqui-oxide (Fe 2 3 ) 7.76 



Ferrous oxide (FeO) 2.64 



Manganous oxide (MnO) 0.96 



Lime (CaO) 2.08 



Magnesia (MgO) 0.07 



Potash (K 2 0) 2.63 



Soda (Na 2 0) 2.44 



Ignition , , 4.42 



Total 100. 37 



The rocks of which the above is an analysis correspond with those be- 



* See Note 6 at the end. 



tThe above paper was rewritten from one intended for a history of York 

 county. Some matters not entirely adapted to a paper in the Proceedings, 

 but which were difficult to eliminate, still remain.— P. F. 



