Hall.] b64: [Nov. 5, 1875. 



many large angular and rounded blocks of Oneida conglomerate, Me- 

 dina sandstone and probably Clinton and Oriskany sandstone. These 

 blocks vary from one or two cubic feet to twenty- five, many of them still 

 preserving their sharp angles ; on sevei'al blocks I could clearly define 

 Glacial scratches. 



Flat and angular boulders which I have observed still imbedded in 

 their original position, are lying at different angles to the horizon. Toward 

 the lower part of the bed of sand, gravel, and boulders, I have noticed 

 frequently a la^ge amount of angular and broken bed-rock or mica schist. 

 A few boulders of Oneida and Medina just south of Pine street and west 

 of Forty-fifth street were also observed. The average line of deposit of 

 these large boulders is N. 42° E. or at right angles to the average course 

 of the Schuylkill River. 



Iq carrying this line northeastward it crosses another similar deposit 

 between the tracks forming the Y at the junction of the P. C. R. R. and 

 N. Y. branch, about the corner of Thirty-eighth and Button streets, 

 and another more extensive deposit near Thirty-eighth street and Girard 

 avenue. The excavation is now going on near Girard avenue, and I was 

 enabled to see many of the larger blocks still in position ; the average 

 of these are deposited at angles to the horizon. 



Among those at Thirty-eighth and' Hutton streets are blocks of Oneida 

 conglomerate and Medina sandstone. Large quantities of New Red sand- 

 stone, and a few blocks of trap rock were also observed. From all these 

 evidences I have concluded that this belt of drift deposit is no other than 

 a Glacial moraine, formed by the Schuylkill Glacier receding from the 

 site of the City. It is very possible that we have here a complicated system 

 of moraines formed as the scratches in the North by the ice at different 

 stages of its existence. J. H. Harden, M.E., procured some specimens of 

 conglomeratic sandrook, with casts of Spirifer which I have been unable to 

 determine. Mr. J. C. Smith afterward obtained a specimen of Oriskany 

 sandstone with Spirifer arenosus, from a deposit west of Forty-fifth street 

 and north of Walnut. 



I am indebted to Mr. J. H. and E. B. Harden for the accompanying map, 

 on which they have carefully located all the principal boulders observed 

 in the locality first mentioned. One fact I will add is, that the surface 

 of the gneiss where laid bare is comparatively smooth, and shows evidence 

 of having been polished, though so soft as not to retain the marks of 

 Glaciation. 



