1878. ] Recent Literature. 621 
CC, CCC, etc., relate to the counties lying in the south-east angle 
of the State, which have been assigned to Prof. Frazer. 
Report C, 1874, is devoted to a study ia York eis Adams 
counties, but more particularly the form ages 0 77 
describe 126 ore banks, both new and old (at that date), and 
their correct location on the general map renders apparent for the 
first time a law governing their position in definite horizons. 
Pages 78 to 87 describe Section 1. The description differs from 
the same section as given by Rogers in some important particu- 
lars. In it the first reliable measurement of the perpendicular 
thickness of the “ Auroral” limestone, made during the survey, 
finds place. Prof. Rogers took the clearly marked planes of fine 
lamination for cleavage and occasional joints of low angle for that 
of fine bedding; by which means he reduced the total thickness 
of the measures very muc n the synclinal, whose axis lies 
very near the Wrightsville—Columbia bridges, the thickness 
appears as 2800 feet + 
It may be rem arked, as a new feature in delineation, that the 
symbols characterizing the different strata are continued for about 
3000 feet above the line of ocean level as well as below it, the 
present surface being indicated by a profile. This permits a more 
comprehensive view of the differences between penanam, empha- 
sizes faults, and hints at the possible amount of e 
Section No. 2, across the mesozoic beds, is P atecaation as 
exhibiting an anticlinal on their southern margin. On pp. 104- 
114 some chemical and structural differences are shown a raisin 
among the limestones united under the name of Auroral. Later 
we have an interesting chemical and anes analysis of the 
dolerytes of Adams county, in which they are shown to differ 
from those of Connecticut, in having two Bok Labradorite and 
one of Pyroxene. 
Prof. fesser's view of the origin of the limonites is favorable 
to their derivation, in the main, es the pyrite and carbonate of 
_ iron among the hydro- mica schis 
eport CC continues the SRE of the survey of York and 
dams counties with part of that of Franklin. The important 
magnetic ore of Dillsburg is described, and some striking illus- 
trations of the manner in whic ch the ore and rp occur in these 
a geometrical method, as poai to their structure, he reaches the 
conclusion that the measures of the New Red have not been dis- | 
turbed by uplifts, as has generally been assumed. 
horough explorations of limited areas, such as are described 
in the present reports, furnish the most exact knowiedge irene = 
