222 Scientific Intelligence. 
The Cumadizn okies ail find in these he a dias statement of . 
~precisely the view which er saniaebiie have learned to entertain y : 
their week’s excursion last su 
Whatever errors Rogers oe have made-and:s we all make err 
‘one can charge him justly with so tremendous a blunder as that of re 
garding the Highland ra nge as a metamorphic repetition of the Silurian 
sediments, He mistook indeed the crystalline limestones engaged among 
‘the Highlands for metamorphosed synclinal outliers of No. is aL 
Franklin (see page 62, New seeer Report); but this is an excepti 
case, | 
represented as sunk among the gneiss hills on Rogers’s long sections ing 
New Jersey Report; or by referring to the many sections (made very 
nearly at the same time) of the ee Silurian valleys among the : 
ham hills of Pennsylvania. Professor Cook has seen horizontal Pots — 
dam or Calciferous beds overlying ‘as — Franklin limestones; 
(see this Journal, [2], xxxii, 208) ; and there are exposures of sim 
ilar crystalline limestones, west of New Jersey, where the evidence is i 
rather in favor of, than against, aa subsilurian age. Prof. Roger's a 
synthesis of Appalachian ; geology was on too grand a scale to permit 
to overlook as a whole and in the main the mutual sslatiooaitl of the 
Silurian and Azoic Systems. The words which me uoted meer ‘ 
trating :— 
“ As the same strata [the Silurian], moreover, hold asimilar rai 
our ae rocks throughout eae ntire range, from Vermont to Al | 
tates... .with the synonyme of the Appalachi 
tem - Strata.” (p. 44. Gneist 
On page 12, Rogers designates the Highland rocks as ee Staten 
system, and, e 13, carefully distinguishes them from ie 
Island, Trenton, Philadelphia rocks, on the hes bsequently 
tinguishes t fr he Potsdam, Trenton, one Hudson river I 
,on the North. = page 11, he gives his column of Forney o 
places mary Rocks” of the High lewda, ainiuveliell No. 6, 
“ Lower ace Rocks ;” “a white quartzose sandstone, 
coarse and friable: occurs only in a few localities” ; and page 
“are devoted to a Chapter on these rocks, under the heading “Prima 
Rocks of the State: Geology of the Highlands.” Jer 
a ces no geologist, even of small capacity, could study the ang 
Hei ec ae the Durham Hills of Eastern Pen nagteania in an 
the South Mountain and Blue Ridge, and ie 
ipso ; ae less = it as a conviction, that their strate 
representatives of the Silurians. We know vey 
