Manual of Geology: Treating of the Principles of the Science With Special Reference to American Geological History, Etc

By JAMES D. DANA. 8VO. Philadelphia : Theodore Bliss & Co. London : Trübner & Co.

No work on any science has yet been published in our language more exhaustive of facts, more clear in statement, or more philosophical in general character and arrangement, than Dana’s “ Mineralogy,” as presented in its last and revised edition.

Of course, the announcement of a “ Manual of Geology” by the same author could not fail to excite hopes that a long-felt want on the part of the American public was to be met, a void in our scientific literature to be filled. Nor are we disappointed in our expectations, now that the work has appeared and time has been given for its careful perusal. On the contrary, we feel a degree of satisfaction that might perhaps express itself too strongly in praise, if we were not withheld by the supposition that a proper notice of the contents of the volume would do more for its appreciation by the reader than any language of eulogy.

What, then, is the distinctive character of the work, and wherein do the contents so differ from previous publications as to claim our especial notice ?

In the first place, we would state, that, while it is a manual of general geological knowledge concerning the history of the earth and of life on its surface, and full of information concerning the strata and geological phenomena of all parts of our globe, it is yet peculiar, inasmuch as it treats of the principles of the science with special reference to American Geological History. In this will be found its great value to American students; for who of them has not had his patience tried, and his enthusiasm often chilled, in vain attempts to solve the questions which have sometimes arisen in his mind concerning American geology, and has not sought their solution in the only way open to him, — a consultation of innumerable State Reports, and other publications, not half of which were accessible when required ?

Another distinctive feature of the work is the prominence given to Historical Geology, or that portion which treats of the successive formation of the strata of the different periods, and of the development and characteristics of the life upon the surface. The whole treatment of this exhibits in a marked degree the extended research and philosophical ability of the author.

Physiographic Geology. — This embraces a general survey of the earth’s features : its continents, oceans, lakes, river - systems, oceanic and atmospheric currents, climates, distribution of forest - regions, deserts, etc.

Lithological Geology. — This treats of the rocks, and of their arrangement: the first embracing an account of all the important chemical elements that enter into their constitution, the minerals and organic materials that occur in their composition, and the kinds and distinguishing characteristics of those that make up the earth’s surface ; the second presenting the arrangement of rocks, stratified and unstratified, — the structure due to deposition and other agencies, — the dislocations of strata, and the consequent faults and distortions of fossils contained in them, — together with considerations upon the age and chronological division of all the strata of the earth’s surface. Historical Geology.— This third part of the volume, and that which peculiarly characterizes the work, opens with some general remarks upon the divisions in Geological History, and the announcement of certain important principles to be kept in view while considering the subject. The progress of life is then described as the basis of subdivision into Geological Ages ; and the subdivisions of geological time are presented as follows: —

I.Azoic Time or Age. II.Palæozoic Time. 1. The Age of Mollusks, or Silurian. 2. The Age of Fishes, or Devonian. 3. The Age of Coal Plants, or Carboniferous. III. Mesozoic Time. 4. The Age of Reptiles. IV. Cenozoic Time. 5. The Age of Mammals. V.Era of Mind. G. The Age of Man,

And in connection with this is given a table of the further subdivision of this history into Geological Periods, and a map showing the distribution of the rocks of each of these periods over the surface of the United States.

The great divisions above given are, as stated, essentially the same as proposed by Professor Agassiz, who, however, made the era of Fishes to embrace the first and second ages of Palæozoic Time, the Silurian and the Devonian, instead of restricting it, as now done, to the latter, and calling the former the Age of Mollusks.

Following these general considerations, each great division of geologic time is successively taken up, commencing with the Azoic. Each period of the several divisions is treated of in order; and the rocks of each epoch and their distribution described, first, us they exhibit themselves in America, — then, more briefly, as they appear in Europe. A full account of the life that manifested itself in each epoch, both vegetable and animal, is likewise given in the same order. The igneous and other disturbing agencies are then considered, and general remarks added upon the geography, the character of the surface, and various phenomena of the period.

The whole of this portion of the work is abundantly illustrated with well-executed figures of all the characteristic species that distinguish the several periods, mostly drawn from American examples.

Dynamical Geology. — This particular branch of the subject is made less prominent than usual in geological works, but it will not be found lacking in any point.

The subject is presented in the following order:—

1. Life as an agent in protecting, destroying, and making rocks.

2. Cohesive Attraction.

3. The Atmosphere as a mechanical agent.

4. Water as a mechanical agent.

5. Heat as an agent in volcanic phenomena, igneous eruptions, metamorphism, veins, etc.

6. Movements of the earth’s crust, plication of strata, origin of mountains, earthquakes, etc.

7. Chemistry of Rocks.

Under the first head, we have much interesting matter concerning peat and coral formations, coral reefs and their origin, illustrated with figures.

Under the head of Water as an Agent, some plates are given, new to the general reader, of the remarkable canons of the Colorado, which so well illustrate the powerful agency of this element in wearing away for itself deep channels in the strata. Under the same head is an interesting essay upon Glaciers, with figures, one of which is a reduced copy of a sketch in Agassiz’s great work, representing the Glacier of Zermatt, in the MonteRosa region.

Under the head of Heat as an Agent, we have, as might be expected, interesting and valuable matter upon volcanic phenomena, and those of metamorphism.

We have thus briefly passed in review the contents of the work, and without criticism, too, for we would scarcely have a sentence in the book altered or omitted. Yet we do not always concur in all the views expressed or implied by the author. For instance, we consider the evidence of the Jurassic age of the Ichnolitic strata of the sandstone of the Connecticut River too strong to allow of their being any longer classed among the Triassic. We certainly differ from him in much that is said upon the subject of Man, as of one species. Yet we do not care to dwell upon these points, especially the latter. Our author will not expect to find all readers agreeing with him upon such mooted questions.

We do not think that we overestimate the value of this work, when we express our belief that its publication will mark an era in our geological progress. By this we do not mean to imply that its character is such as to be of great service to those among us who are already learned in the geology and palæontology of our continent; but we do mean to affirm, that, by the efficient aid which this work will be to them, thousands and tens of thousands who have sought hitherto for information on its great subjects, when seeking was literally “groping in darkness,” will be helped forward to a degree of knowledge respecting the history and life of our globe which they could not otherwise have attained.