1026 Review of Report Cı, 2d Geol. Surv. of Penna. [Octo 
On p. 104 Professor Lesley speaks of Dr. Hartman’s geological 
map of Chester county as defining the S. E. limit of the “Tale-mia — 
belt.” On p. 105 he says, “Z have defined such a border;” which — 
language would imply that the supposed border between the 
‘hydro-mica and chloritic areas, which is given in the colored map, — 
emanated from Dr. Hartman or Professor Lesley. The writer has — 
never seen Dr. Hartman’s map, but the chance of his boundary 
agreeing exactly with Dr. Frazer’s in such a country is not one — 
in millions. The boundary now printed on the colored map is — 
the identical boundary traced provisionally by Dr. Frazer on his 
first manuscript map, and afterwards so completely disproved by — 
its author that it was abandoned. Aust 
It will also strike the average reader as in questionable taste to 
refer (p. 106) to the supposed opinion of the late Professor John 
F. Frazer, which he entertained, if at all seriously, simply asa 
hypothesis which he never had the opportunity to decide; and 
force Dr. Frazer into an apparent opposition to his father, by 
the misleading words that the latter “assisted Professor Rogers 
in 1853 and was personally very familiar with Chester county, — 
Professor John F. Frazer did not study the geology of Chester 
county under Rogers nor subsequently, and he would have been 5 
the last to present the results of desultory observations du Fie 
his visits for recreation as a definite theory founded on s 
work. Ar 
The third division is the “ Downingtown valley,” and the fo 
the “Northern gneiss and Potsdam sandstone region.” 
latter Professor Lesley follows Rogers, alluding to the “ a 
trap” traversing the shale, the fact being that if there be any £ 
stone in this region it has been entirely overlooked by a 
observers, its quantity is very inconsiderable, and its pack 
entirely subordinate to that of the dolerites and syenites © 
make up almost, if not quite all, the igneous masses of the ` 
(new red) sandstone and shale. To this is appended nee 
summary of the iron works, past and present, of the co 
A word is due in explanation of the character of 
work (i. e., Township Geology) which appears in Cy 
months of 1879 and five months of 1880 were spent by 
the collection of facts for the proper report on the geology 
most difficult region. It is probable that two more ©" 
