July 26, 1895.] 



SCIENCE. 



109 



region that have appeared since. The 

 Gogebic district, that has proved the key 

 to the structure of the other ranges, had 

 not yet developed a mine when seen by Dr. 

 Eominger, and in the older ranges the ' soft 

 ores,' now the chief source of supply, were 

 looked upon, when known, with more or 

 less contempt. The paper is a further am- 

 plification of the author's previous report 

 and is to be considered in this connection. 

 Its chief value to-day is in its historical 

 bearings and in the fact that it does its 

 author the justice of finally issuing his work. 

 Otherwise, lacking, as it is, in sections, geo- 

 logical maps and illustrations, it forms for 

 a general reader a rather disjointed series of 

 observations. 



The chapter on the Keweenaw group of 

 copper-bearing rocks stands much better b_Y 

 itself. The geology of the country is much 

 simpler than in the iron regions, and not 

 much important additional work has been 

 done in the last ten years. The report is 

 brought down to date, also, by recently ac- 

 quired data. Accurately plotted cross- 

 sections afforded by the deep Tamarack 

 shafts, and bj' long prospecting drifts in the 

 Calumet and Hecla mine, illustrate ad- 

 mirablj' the astonishing succession of ba- 

 saltic eruptions that go to make up the 

 Keweenawan formation. The report fur- 

 nishes thus an excellent short account of the 

 geology of Keweenaw Point, of the adjacent 

 mainland, and of the copper mines. As 

 such it is to be commended to the general 

 reader. When we read of the extensive 

 prospecting and exploration that have so 

 widely opened up the surface and that have 

 so often been without remuneration, we 

 cannot but regret that we do not better un- 

 derstand the laws of the precipitation and 

 distribution of the copper. Despite Pro- 

 fessor Pumpelly's brilliant and suggestive 

 thesis, most observers familiar with the 

 mines feel that the whole story has not 

 yet been told. 



Part II. is a very valuable contribution, 

 and more than Part I. brings out that which 

 is new. Dr. Hubbard's introduction is 

 timely. It sets forth the views of Ochsenius 

 on the origin of thick deposits of rock, salt, 

 gypsum and their associates, and places be- 

 fore American readers what is reallj' the 

 only good explanation of their formation. 

 The ' bar theory,' based, as it is, on true 

 chemical principles and necessary geological 

 relations, laj^s us under obligations to Och- 

 senius that are no less important in theii- 

 scientific than in their economic relations. 

 As applied to petroleum, however, there is 

 little in the geology of our serious oil re- 

 gions, so far as yet opened up, that indi- 

 cates any notable connection between the 

 ' mother liquors ' of an evaporating estuarj' 

 and these stored up reservoirs of hj^drocar- 

 bons. The main part of the paper consists 

 of Dr. Lane's revision and elaboration of 

 notes which were mostlj- accumulated by 

 the late State Geologist, Charles E. Wright, 

 whose untimely death removed a vigorous 

 worker in the midst of his career. The 

 records of the wells sunk for brines or in the 

 search for oil and gas have aflforded a vast 

 amount of valuable information about the 

 stratigraphy of the Lower Peninsula. These 

 have been elaborated by Dr. Lane in a very 

 admirable waj^ After a brief introduction 

 regarding the ga^JS in the record, and the 

 errors that creep into observations of this 

 character, a review is given of the stratig- 

 raphy of this portion of the State, which 

 is to be commended to any reader who de- 

 sires a brief account of the thickness and 

 arrangement of the formations. The records 

 are then plotted in numerous diagrams,' 

 from which sections are assembled that cross 

 the geosyncline in five or six different places. 

 A descriptive text accompanies the sections, 

 arranged bj^ towns in alphabetical order. 

 The report cannot fail to be of equal interest 

 to scientific men and to those who are en- 

 gaged in the rapidly growing industries 



