1024 Review of Report C,, 2d Geol. Surv. of Penna. (October, 
328, and many other places of the report under review, 
&c.] | 
The first chapter of the book under review (by the chief geolo- 
gist, Professor J. P. Lesley) consists of thirty-two pages, of which — 
the first six pages contain a general statistical account of the his- 
tory, population, roads, &c., of Chester county. Here a divisionol 
the county into five regions is based upon Rogers’s old system, and 
besides its very artificial character, contains faults which Rogers 
himself would probably not repeat now were he to re-write it 
These divisions are, 1st. “The southern region of Philadel- 
phia gneiss,” which neither Messrs. Hall nor Frazer have been 
able to adopt. This region is not defined by Professor Lesley, : 
but judging from the water courses mentioned in connection 
with it, it includes much of the chlorite and hydromia 
schists. e 
Chapter 11 is the “ Geological Description,” and commences by 
alluding to the two maps of Chester county, one by Frazer, 
printed in 1880, and the other by Hall in 1882. The chief geolo 
gist here says, “ Professor Frazer is dissatisfied with several de 
tails of the map as published, and especially with the manner of : 
representing the hydromica schists south of the Chester valley” r 
After repeating these objections in the Assistant's own WO!” 
Professor Lesley states the reasons for printing the map, with 
division which Frazer had after two years’ work fi iled to justi, 
to be that “had the pink color * * been HSE er 
schist area * * it would have confused the genle? A 
`- 
should be allowed to agree with his own vi 
printed work, or altered in an important particular, 
it might agree with the views of others? Even Mr. 
take the responsibility of this change, for he says 
hydromica schists (of the South Valley Hill belt) spread 
quoted passage, ‘The dips in this area, in fact all the measures, aram usually low : 
very varying directions, and the angle with the horizontal pan a any oe 
e notes were made in 1879 or before Mr. Hall had exp Eo 
about the “ southern gneiss region.” 
i er says in t ” 
1 Speaking of feldspathic gneiss, which may be Potsdam, Fraz annii 
