246 



PROCEEDINGS OF THE ACADEMY OF 



[1883. 



map would be ^'^ of an inch ; its outcrops are almost continuous, 

 and between, its existence in the fields is constant. 



Dr. Frazer attempts a joke founded upon his impression of the 

 absence of an allusion to the serpentine in Radnor and Easttown, 

 in my criticism of C 4. It would have been well for hira to liave 

 read the paper again. He will find on page 33 an " allusion " to 

 the serpentine in Radnor; on page 34 a map of the outcrops in 

 Radnor and some of those in Easttown. 



I did not describe the echelon structure of the serpentine out- 

 crops as a theory, as Dr. Frazer says, but, as a fact, the under- 

 ground structure I do not attempt to demonstrate. That our 

 observations agree within limits that do not affect the question, is 

 shown in the table given below. 



The lines of strike are in part deduced from the dips given by 

 Dr. Frazer, but it may be well to quote from C 4, p. 218 : " The 

 ser[)entiue * * * where exposed, it is so fractured and bi'oken 

 as to make the determination of its dip ver3' difficult or altogether 

 impossible. But its strike cannot unfrequently be pursued in 

 almost straight lines for miles." 



For this reason, in recording my observations, I preferred to 

 give the dip and strike separately — for the dip varies greatl}', the 

 strike does not. 



Outcrops. 



Strike | Strike, 



on map, Frazer, J. F.I, 



C 4. Oct., '83. 



1. yi mileE. 

 of Radnor 

 station, 



3. Ya mile N, 

 W. of 

 Radnor 

 station. 



6, S, W, of N, 70 E, 

 Old Eaf'le 

 station 



7, N, W. of 

 and near 

 Devon 

 Inn, 



9, Ivister, S, N. 76 E. 

 of Berwyn. I 



Nearly 

 E, and W. 



± N. 30 E, 



90° from Dip. 

 Frazer. 



K 70 to 85 E. 



N, 70 E, ! 

 N. 60 W. 

 (?N, 60 E, ?)' 



Strike, Rand. I Difference. 



N. 40 E. 



N. 40 E. 



Nearly 

 E. and VV. 



N. 60 E. 



N. 40 E. 



N. 50 to 60 E, 



N. 40 E. 



to 20O 



10=> 

 ISOOor OO 



lOO 



OO 



A line joining the outcrops 6 and 9 on map C 4 is N. Si E, 

 One joining the Radnor outcrops on map by Hopkins, N, 80 E, 



