94 PROCEEDINGS OF THE ACADEMY OP [1890. 



Hill, the norlhern and southern bilts ought to join at the eastern end of the syn- 

 clinal basin ; but they apparently do not." 



C^ p. 15. " The serpentine and associated rocks lie in synclinal basins. This is 

 the rule in regard to ail serpentine areas in Delaware county and probably with 

 most of the serpentine in this district." 



C^ p. 57 (C & I). " The serpentine crosses the northern portions of the township 

 (Upper Providence) in two belts which indicate shallow synclinal basins and the 

 erosion between these areas or basins exposes the underlying mica schists." 



C^ p. 13. " The Delav\ are county deposits demonstrate the fact that the serpen- 

 tine areas are shallow synclinal basins, many of them saucer-shaped." 



C* p. 13 (G). " There is a small area of steatite close to Gulf creek and near a 

 limestone deposit. I think that there is no question that the steatite belongs to the 

 same horizon as the serpentine. The belt of serpentine" (B) "which makes its ap- 

 pearance in Radnor township belongs geologically to the serpentine belt which ex- 

 tends across the Schuylkill river and through Lower Merion township, Montgom- 

 ery county" (C), "and is a direct continuation of the belt which passes through the 

 corner of Tredyffrin township, Chester county, and passes north of West Chester" 



" The serpentines throughout the central portion of Delaware county" (I. K. L.) 

 " belong to the same horizon as those in Lower Merion Township, Montgomery 

 county" (C. F. G.). 



From the above facts it will readily be seen that all the serpentines through this 

 region belong to the same geological horizon." 



C 5 p. 14. " It is safe to assume that the serpentines are one of the most recent 

 deposits." 



C ^ p. 65 (K). Middletown Township. "There are numerous small areas of 

 steatite, anthophyllite, and actinolite, indicative of the serpentine horizon, through 

 the southern and southwestern portion of the township but these rocks seem to be 

 confined to very small areas lying upon the schists and gneisses which are exposed 

 in the escarpments." 



C ^ p. 64 (I). " Light feldspathic granite is formed in this township (Middletown) 

 associated with the serpentines." 

 •" The geological position of this granite is below the serpentines." 



The term " talc mica " is applied above to the hydromica schists 

 of the South (Chester) Valley Hill, sometimes called chlorite schists. 

 In fact they contain neither talc nor chlorite unless in very minute 

 quantity. 



Upon studying the relation of these serpentines to the adjacent 

 rocks the fact is at once apparent that most of these outcrops, and 

 those most extensive, occur along the margin of the Laurentian rocks, 

 and very close to that margin, while some of them, generally small 

 in area, seem with equal certainty to be some distance from the Lau- 

 rentian, and to have jio connection with it. 



To the former belong : 



A. Easton. B. Radnor — West Chester, C. LaFayette. D. 

 Southwest of Newtown. E. Willistown. 



And to the latter : 



F. Steatite. G. Northerly Radnor. H. Cresheim Creek. H. 

 Southeast of Marple schoolhouse. K. SouthAvest of Media, 



And probably I. "West of Media. 



