|VoL. v., No. 114.
��Sitpciioi' gfology. To the class of foiiiuiliona later than the Keweenawnn. he refers the fos- silil'erous Cambrian saDflsione of the Missis- sippi vidlev, and llie horizontal sandstones of the Su|>erior basin, known in looal jjoology as Ihe ■ eastern " and 'western' sandstones. To the seiies ol' older fornialions lie refers llie Anintikie group, the original liurooian, and the Penokee. Marijuctte. and Menominee IIu- ronian groups. The Ibesiliferous sandstone of the Mississippi valley (Fotsdnm) he confldeullj considers later than the Keweenaw series, because it uneonformablv overlies it. with fvidence of great intervening ei'osion. The
- eastern ' and ' western ' sandstones ulso are
held to be newer, because they adjoin the Keweenaw series by nn (.■on form able contacts associated with fault-lines. These three sand- stones he refers to essentially the same horizon, — the Potsdam, or its immediate downward continuation. In support of these views, he cites a large array of specific evidence, and gives precision to bis diHcussion by maps and diagrams. The older formations named are se{ianited from the Kewcenawan on the grounds of unconformable relations, and dis- cordance of character.
The slratigraphical discussion is fittingly closed by a sketch of the Lake- Superior syn- clinal. The existence of a downward flexure embracing the western part of the basin was long since made known by Foster and Whitney. Professor Irving and his Wisconsin colleagues, n few years since, determined its south-westerly extension into the bordei-s of the Mississippi basin. The author now makes an important extension eastward so as to embrace nearly all of the lake's area, the trough assuming a cnn'ed. rudely reniform conlour-
The monograph is closed by « chapter on the copper deposits, which were, however, not special subjects of investigation.
The treatment throughout is candid and able. There is a close adherence to facts, and the conclusions that legitimately flow from them. The memoir is a valuable contribution to gen- eral geology. The horizon of which it treats has long lain under a cloud of obscurity, if not of actual chaos, in t'urope as well as in America. The distinct differentiation of tlic i'ormntions of one important field cannot fail to aid in the study of all others. When equalh' explicit descriptions of other regions involving this horizon shall be at command, we shall ilonbliess be on the thresliold of agreement as lo its tasonoraic place and value. Present dis- agreement is largely an expression of imjier- fccl knowledge and provincial study.
��WORLIKSTUFF.
■ WiiENCB came this world?' and 'Whither is it going?' arc questions of never-tiring interest lo mankind, — questions upon which they have ])ondered for long ages, and which are still unsolved. Where is the roan who, without a shudder, can tnm from the beantind life around him, and in fancy contemplate a cold, cheer- less, dark, lifeless condition of the world to- wards which we have every reason to believe it is tending?
In the book before us we have an effort made lo weave the various speculations of others, re- garding the evolution of the universe, into a continuous aud harmonious whole by an admix- ture of the author's own ideas. Professor Winchell is well known from his past efforts to popularize science, and for his speculative tendencies ; and i>erhaps he, of all American writers, is best fitted to |>opularize a subject like the one he has chosen, and commend it to the interest and attention of the musses. The work is to be judged rather by its success or failure as a popular presentation of the sub- ject, than as an original contribution to cosmical science. In either respect, the book is disa]>- (winting ; for onr author, instead of keeping in a fleld in which he has perhaps no 8U|>erior in America, has attempted u middle ground. He has written so that his treatise occupies a higher plane as a scientific treatise than his previous books, although, as is the tendency of all spec- ulative minds, the presentation of theories has been mistaken for the presentation of evidence and proof. Again: as a popular presentation of the subject, the work falls below the other books of the author, so far as we are acquainted with them, and doubtless many |)ortioDs will be considered by its readers os dry and pedan- tic. On the other hand, the work shows iu many ports a mode of presentation of certain difHcult questions that is well worthy the care- fhl study of the majorilv of our scientific writers who have any desire that their readers shonld understand what they are writing about.
The author holds that the dust and iron globules found in the depths of the sea and on the mountain-tops are of meteoric origin, — a veritable world-sluff, jwrvading all space, — and that bj' and I'rom this stuff world-systems are evolved. lie supposes that a tendency for immense amounts of these dust particles to associate about a common centre leads to the formation of nebulous clouds, which, from n
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