1883.) Review of Report C, 2d Geol. Surv. of Penna. 1021 
three hundred and ninety-four pages which follow this heading 
are not in any sense a report of Persifor Frazer. That person is dis- 
posed rather to regard them as constituting a scrap-book of some 
new, some truc, some old, and some other things originating from 
many persons, living and dead. One characteristic feature of the 
book is the way in which one of its parts stultifies another. After 
this perhaps comes the incongruous divisions of the subject 
(divisions as incommensurable as inches, pounds and years), 
which are woven together by the eminent editor so that 
bewildered reader knows not whether he is reading Hartman, 
Rogers, Lesley or Hall, and only becomes aware after half the 
book is perused, that whoever else he may be reading it is not 
razer 
It is well known to most American and many European geolo- 
gists that Rogers (and many other geologists of his time) was 
clearly mistaken as to the constitution of a large series of rocks 
which he called the “ talc-mica ” series, the error being that these 
rocks contained no talc whatever, the mineral that was taken for 
talc being a hydrous mica of the Damourite group. The term 
“tale-mica” had almost disappeared from the papers of those 
geologists who had kept up their lithology before the Second 
Geological Survey was commenced, and the directors of most of 
the State geological surveys (must we except that of Pennsylva- 
_ nia?) are aware how much the labors of various assistants of the 
latter survey have done to establish permanently, on a sound basis, 
the true relationships of those schists. 
Yet the old name, “talc-mica” region, is retained as if it actu- 
ally defined something, and not only in the quotations from 
Rogers, but in the numerous editorial comments. The magnesia 
Which these schists are supposed to contain (contrary to the 
results of repeated analyses by Dr. T. S. Hunt, Dr. Genth, Mr. 
McCreath, the writer and many others) is made the basis of 
an hypothetical speculation as to the superposition of the South 
Valley Hill series on the limestone? 
_*See p, 103, where also notice an argument in favor of the magnesian character 
OF the schists “ because they have always been known as the talc slate belt.” The 
term talc-mica occurs continually throughout the volume wherever Professor 
__ Lesley’s work appears, although it is universally conceded by geologists that the 
name was given under a misapprehension of the true nature of the hydromica schists 
: ay in reality contain no talc at all, Most reports and treatises on these rocks in the 
. last ten years have recognized these facts, and none more so than the Second Geo- 
