Review of Literature. 121 
Geologist (Vol. VII, p. 241), on the Post-Archean acje of the tvliife lime- 
stones of Susssex county. It is true that the views of Dr. E. Emmons 
since 1846, and of all his school, have made the Taconic strata pass 
through that part of New Jersey, for it is well known that the geology 
of northern New Jersey is but a continuation of that of southeastern 
New York, but the views of Prof. Dana as to the Archean age of these 
gneisses, and of the accompanying limestones, based as they were on 
the supposed infallibility of chondrodite as a sign of that age, have pre- 
vailed very largely, and these ores have therefore been classed as Ar- 
chean. The discovery of Olenellus in the quartzyte underlying the 
limestone effectually removes them from the Archean, and as fatally 
overthrows the dictum that chondroditic limestones are certainly Ar- 
chean, since large quantities of that marked mineral are found in them 
here. It even points to the reverse, and shows that if chondrodite has 
any value as an indicator of the age of a limestone, it marks the lime- 
stone containing it as Taconic. Another important point established is 
the primordial (Taconic) age of the iron ores, and their close association 
with that limestone, which, coming from the so-called Archean region 
in southeastern New York, was carefully traced by Prof. Dana through 
western Connecticut, northward to Stockbridge, Mass., and to Rutland, 
Vt., where recently it has been proved to be of the same age by a similar 
discovery of Taconic fossils by Wolff and Foerste. This bears strongly 
against the idea that any part of the iron-bearing beds of the region 
traversed by this limestone are of the age of the Hudson River. 
The fossils that have brought about this result, and the chondrodite 
which have been found in the limestones, have both been determined by 
associates of Prof. Dana, at New Haven, the former by Dr. C. E. Beecher, 
and the latter by Prof. S. L. Penfield. These results are no surprise to 
geologists who have watched the course of geological research with 
its tendency, relating to the Taconic, during the last six or eight years. 
There are, however, two important points in Mr. Nasoifs report, in- 
cluded apparently in his "conclusions," to which we can not yet sub- 
scribe fully. First, it does not seem sufficiently proved that the blue lime- 
stone is the same in age as the white. It shows some singular contrasts 
and divergences. If both can be found to be fossiliferous that would 
settle it. Second, It is not sufficiently shown that there is no gneiss (as 
distinguished from granite) and that all the acidic crystalline rock con- 
cerned is eruptive. There is avast amount of testimony that the lime- 
stone is interbedded and conformable with gneiss. It is hard to con- 
ceive how a limestone can be placed there, a fossiliferous limestone, and 
a quartzyte, without some other fragmental rocks to accompany them. 
If the limestone and the quartzyte are metamorphosed, what is the 
probable condition of those other fragmentals? Further north this 
limestone is said to be accompanied by conformable gneiss and mica 
schists. 
The Texas Pcriiiiun (ind its Mesozoic Types and Fossils. (Bulletin of 
the U. S. Geological Survey No. 77. as stated on p. 8.) 
In this bulletin is presented a summary of the various kinds of evi- 
dence indicating the Permian age of a certain series of the strata in 
