202 lievlew of Recent Geological Literature. 
Preliminary report of the Dakota School of Mines upon the Oeology, 
Mineral Resources and Mills of the Black Hills of Dakota. Rapid City, 
Dakota. Traasmitted to the Board of Trustees by Franklin R. Carpenter, 
Dean of the school, November 5, 1888. 8vo. 171 pp. This is a valuable 
document; indeed one whose scope and scientific as well as practical value 
do great credit to the enterprising Territory and reflects honor on the 
authors. It consists of three parts: 
(I) Notes on the geology of the Black Hills, by Prof. Carpenter; 
(3) Notes on gold mining in the Black Hills, by H. O. Hofman, and 
(3) Upon the mineral resources of the Black Hills, by Prof. Carpenter. 
Each part deserves more extended notice than we can give at this time. 
The report itself which claims only to be a preliminary one, lacks the 
maps which were planned to illustrate it. But it is to be hoped that 
means will be provided by the Legislature to carry on and to finish a 
work which has been so well begun. 
(1) The Arch;Tean rocks are said to embrace two groups, a western one 
of schists and an eastern one of slates, both containing quartzytes and 
"great beds of conglomerates." Although the author does not mention it, 
this agrees with observations made in Manitoba and Minnesota where the 
Kewatin, a formation essentially of schists, is unconformable below the 
Animike, a great group of slates and iron-bearing quartzytes. In the same 
manner the Black Hills' slates carry siliceous iron ore in the northeastern 
portion of the Hills. In discussing possible equivalents of these series 
with formations in other parts of the United States, w^hile not accepting 
unqualifiedly the opinions of Prof. W. O. Crosby, that they are the repre- 
sentatives of the Montalban and the Taconian, he quotes favorably from 
Mr. Crosby's paper, but with the cautionary remark that the Taconian may 
have to be removed from the Archtean owing to the recent discovery by 
Mr. Walcott, of primordial fossils in what has been supposed to be its 
lowest member. 
Prof. Carpenter includes under the term Potsdam both the remarkable 
quartzytes of the southern portion of the Hills and the nearly horizontal 
sandstones and conglomerates, and separates it, i. e., both these, from 
what he has grouped as Archaean, by a general and conspicuous uncon- 
formity. He does not however make it plain that there is a conformity 
of stratification between the quartzyte and the sandstone. There are "inter- 
bedded ([uartzytes" in the upper member, and s» there are, to a limited 
extent, in what may be supposed to be its equivalent along the bluffs of 
the Mississippi. But there is, besides, throughout Wisconsin and Minne- 
sota, a great unconformable lower quartzyte, and these have in like man- 
ner both been styled Potsdam. This great quartzyte exists in southeastern 
Dakota and it is very reasonable to suppose that its equivalent is also 
found in the red quartzyte of the southern part of the Hills. Again this 
lower quartzyte in its manner of occurrence in northern Minnesota lies 
with apparent concordance of stratification on the slates and gray quartzytes 
of the Animike in some places, and in others it lies unconformably on the 
older rocks. Its positions in Minnesota accord with the hypothesis that is 
advanced by Prof. Carpenter that it was deposited during a time of gradual 
