Apbil 23, 1887.] 



SCIENCE. 



401 



we think Professor Storer's book does. While, 

 in the words of the preface, •' it makes no special 

 appeal to chemists or students of chemistry,' it is 

 nevertheless a thoroughly scientific book in the 

 truest sense of the term. While it is strikingly 

 free from the technicalities of science, its state- 

 ments and discussions are based on so thorough a 

 knowledge of science in its relations to agricul- 

 ture, and so pervaded by the scientific spirit, as to 

 render the book most valuable to all students of 

 agricultural science. 



It is, however, in its felicitous union of science 

 with practice that the book is pre-eminent. Many 

 otherwise good agricultural books suffer from a 

 certain impracticability, arising from a deficient 

 acquaintance, on the part of their writers, with 

 the conditions of practice ; while of others exactly 

 the converse is true. Neither of these faults, 

 however, can be attributed to the present work. 

 While its scientific merits commend it to the 

 student of science, its practical common sense as 

 well as the lucidity and suggestiveness of its dis- 

 cussions will commend it no less to the thinking 

 farmer. Indeed, we anticipate that one of the 

 most valuable features of the book will prove to 

 be that it will, on the one hand, help to remove the 

 prejudice against science which is still too preva- 

 lent among farmers, and, on the other hand, tend 

 to inspire in the minds of students of science a 

 greater respect for, and a more earnest study of, 

 the practices and maxims of successful practical 

 agriculture. 



GEOLOGY OF MINNESOTA. 



The annual reports of state surveys are, for 

 the most part, dull reading, especially for non- 

 residents ; since they are necessarily of a detailed 

 and fragmentary character, showing the progress 

 of investigation in many different directions, with 

 very little completed work. Both the reports be- 

 fore us, however, embody material of more than 

 local interest, and it is desired to call attention 

 here to those portions, without attempting to 

 notice the entire contents of the volumes. 



The notes on the section from Duluth north to 

 the iron-mines about Vermilion Lake give Pro- 

 fessor Winchell's latest views concerning the 

 stratigraphy of the crystalline rocks of north- 

 eastern Minnesota, between Lake Superior and 

 the international boundary. The height of land 

 between Lakes Superior and Vermilion is marked 

 by two distinct ranges, — the high and broad 

 Mesabi Range, composed of eruptive gabbro and 

 red metamorphic granite ; and, north of this, the 



Thirteenth and fourteenth annual reports of the geologi- 

 cal and natural history survey of Minnesota, for the years 

 1884 and 1885. By N. H. Winchell. St. Paul, State. 8°. 



lower and narrower Giant's Range, consisting of 

 gray and red syenites, which have been referred 

 to the Lauren tian, and mark an important anti- 

 clinal axis. North of this axis, and dipping 

 north at high angles, is a broad belt of the 

 green and red jaspery and magnesian schists and 

 conglomerates referred to the Huronian. South 

 of the axis, the Huronian series appears to be 

 concealed by a fault ; but we have above it, 

 dipping to the south in conformable succession, 

 the Animikie slates and quartzites, the gabbro 

 and granite of the Mesabi Range, and the green- 

 ish trap of the cupriferous series, extending from 

 the Mesabi Range to Lake Superior. 



The gabbro, Animikie, and Huronian series 

 are each characterized by important deposits of 

 iron ore ; and this district is, with almost phe- 

 nomenal rapidity, assuming a position of the first 

 importance as regards the products of its mines. 

 The iron of the gabbro belt is, as usually with 

 rocks of that class, titanic. It furnishes the iron- 

 sand of the Lake Superior beach, and. so far as 

 known, has no parallel in Michigan and Wiscon- 

 sin. The iron ore of the Animikie slates is hard 

 hematite and magnetite, and probably parallel to 

 the Commonwealth mines of Wisconsin, but with- 

 out any known equivalent in Michigan ; while the 

 Huronian deposits, occurring chiefly about the 

 south end of Lake Vermilion, consist almost 

 wholly of hematite, and seem to agree closely 

 in character and position with the Marquette and 

 Menominee deposits of Michigan and Wisconsin. 

 The Vermilion Lake mines are being rapidly 

 exploited, and the discovery of these ore-bodies 

 is regarded as marking an epoch in the economic 

 history of Minnesota and the north-west. 



The salt-wells of north-western Minnesota and 

 the adjacent portions of Dakota and Manitoba are 

 believed to give promise of important develop- 

 ments ; and various facts are cited tending to 

 show, that, although the occurrence of carbonif- 

 erous strata in this region has not been hereto- 

 fore definitely known, these brines, like those of 

 Michigan, really have their source in that forma- 

 tion. 



Minnesota, it is well known, is, for the most 

 part, deeply drift-covered, and the solid rocks are 

 rarely exposed, except along the principal streams. 

 For this reason, great geological interest attaches 

 to the numerous deep wells which are being 

 drilled in different parts of the state. They not 

 only show what would be the surface rock if the 

 drift were removed, but also establish the order, 

 thickness, and continuity of the different horizons 

 down to the crystalline foundations of the state, 

 at points far removed from their outcrops. 



In the deep wells of central and south-eastern 



