'Review of ^Recent Geological Literature. 1 19 
We regret to learn that the expense of this work has been so 
largely borne by at least one of the authors, and hope the day 
will come when original investigation will be regarded as part 
of the duty of every j^rofessor of science and that he will be 
enabled to do it by the possession of leisure and the necessary 
instruments. 
We must add in conclusion that the work is amply, we may 
say profusel}', illustrated and that the illustrations are good. It 
may be obtained from the authors at Granville, Ohio. 
REVIEW OF RECEiYF GEOLOGICAL LITERATURE. 
/.s t/ierc a Iluronian Group!' By R. D. Irving. (Am. Jour, of Sci., 
vol. xxxiv, Sept., Oct., Nov., 1887). In this well written paper we 
have evidently the fruits of careful and laborious study. All the 
statements and inferences are based on an extensive series of patient and 
painstaking observations made in the field. 
The author uses the term group in accordance with the system of 
nomenclature proposed by the director of the United States geological 
survey. According to this system the term group would include all the 
sedimentary deposits of such a division of geological time as has, by 
common consent of geologists, been called an age. Thus we have a 
Carboniferous age, a Devonian age, a Silurian age, etc., and the stratified 
sediments that accumulated during the three ages give us the correspond- 
ing Carboniferous, Devonian and Silurian groups. 
Using the term group as thus defined, and limiting the observations 
first of all to the original or typical Huronian as "mapped by Logan on 
plate three of the atlas to the Geology of Canada, 1863," the author pro- 
ceeds to answer the inquiry whether " there can be carved off of the 
upper portion of the great complex which has been called Archaean, 
a series of Huronian rocks; a series entitled — by structural and 
genetic separateness, by clastic origin, by largeness of volume, and by 
the being made up by subordinate divisions of the formation rank — to 
the rank of a group, i. e., to a rank equal in classificatory value to the 
Cambrian, Silurian, etc." The results of the author's observations lead 
him to return an affirmative answer to the inquiry, and he therefore pro- 
poses to establish a Huronian group that shall have the same rank as the 
Cambrian, Silurian, Devonin or Carboniferous. 
Some of the facts presented and conclusions arrived at in the paper 
are best expressed in the words of the author's synopsis of its contents. 
"Throughout the region stretching from the north shore of lake Huron 
