1883.] Geology and Paleontology. 965 
GEOLOGY AND PALASONTOLOGY. 
EOLOGY OF Lower MERION AND ViciniTy.—My attention ha 
just been called to the articles in the May number of the Nart- 
URALIST by Dr. Frazer, and in the June number by Mr. Hall, on 
the Geology of the Chester valley and vicinity. 
On page 523, Dr. Frazer has evidently written without exam- 
ining the paper referred to (Acad. Nat. Sci. Phila. Nov., 1878), or 
e map, when he credits me with calling the belt S. of the lime- 
stone of Gulf creek the second and that at Paoli the third of “ ap- 
proximatively parallel beds,” nor can I believe either he or Mr. 
Hall has ever examined the northerly belt which lies about one- 
quarter of a mile north of the outcrop of the belt east of Radnor 
station, and with a strike approximatively parallel. 
If the serpentine outcrops between Radnor station and Paoli 
were described, as Dr. Frazer intimates, it is to be regretted that 
he did not refer to such descriptions. If they were not described, 
but were we// known, is it improper to describe them, if they were 
erroneously set out in the only recent map published, to my knowl- 
edge, a map issued by one connected with the geological survey 
of the State, and of very recent date, when my paper was written, 
and this even if they were correctly delineated upon an unissued 
ap 
Dr. Frazer thinks the connecting of the serpentine areas in 
Radnor, Easttown, &c., by a straight line curved at its eastern 
extremity a mere matter of judgment, while I do not understand 
him to dispute the correctness of my map, which shows the act- 
ual outcrops to be at angles with Mr. Hall’s line almost through- 
out. 
Few geological problems are difficult of solution if we may but 
fill a gap of two miles exhibiting constant surface indications of 
certain rocks by the imaginary existence of other rocks of which 
there are no indications. 
Vill he mention an outcrop in Lower Merion, Radnor, or 
Upper Merion at which one would find any difficulty in distin- 
guishing the serpentine from the rocks bounding it? More 
than this, the rocks of some of the outcrops not shown in 
C 6 are precisely the same rocks which make the outcrops that 
are shown. 
It may be that the sandstone and sand beds on the north flank 
of the South Valley hill and the associated iron ores are not Pots- 
dam, but inasmuch as east of the Schuylkill the Potsdam occurs 
In precisely that position, this extensive deposit is at least worthy 
