126 GEOGRAPHIC LITERATURE 



A Treatise on Rocks, Rock- Weathering, and Soils. By George P. Merrill, 

 Curator of Geology in the National Museum, etc. Pp. xx + 411, 

 with numerous illustrations. New York : The Macmillan Company. 

 1897. $4.00, net. 

 During the present generation a score of students in this and other 

 countries have turned attention to the soil ; and, while it may be ques- 

 tioned whether they have yet succeeded in organizing a science of the 

 soil, it may be affirmed that they have made substantial contributions 

 toward such a science. Hitherto most of the publications pertaining to 

 the subject have been technical or at least special, and confined to official 

 documents ; but now comes Professor Merrill, already favorably known 

 through professorial work and general w^riting, with a popular work on 

 soils adapted to both class work and genei'al reading. His apology for 

 the publication — " It is believed that no apology is necessary even in this 

 day of many books for bringing out the present work " — emphasizes the 

 importance of the subject : Human life and the ancillary animal and vege- 

 tal life of the land depends on the soil ; the fullness of the earth is its 

 wealth in soil ; and the worthiest science — albeit in very infiincy yet — is 

 that pertaining to this richest of all natural resources. Every student, 

 every teacher, every citizen, every statesman, ought to welcome such a 

 contribution to human progress as this useful treatise. 



The work is arranged in live parts, each divided into several chapter- 

 lets. In the first part rock's are discussed as to their constituents, their 

 physical and chemical properties, and their modes of occurrence, and in 

 the second they are classified as (1) igneous, (2) aqueous, (3) seolian, and 

 (4) metamorphic ; thus this part of the work deals with rock-making, 

 and sets forth the laws involved in the development of the fundamental 

 constituents of the external earth. The next two parts are devoted, re- 

 spectively, to the weathering of rocks and to the transportation and 

 redeposition of rock debris, and in them the unmaking and remaking of 

 rocks are admirably though briefly expounded. Part V, in which the 

 originality of the work is concentrated, is entitled "The Regolith;" 

 under this new term (derived from Greek words for blanket and stone) the 

 unconsolidated material mantling the hard rocks is discussed in detail. 

 The warrant for introducing a new word for the soils, subsoils, and other 

 superficial materials of the earth arises in daily need ; several terms have 

 already been employed — "soil," "earth," etc., in general, "drift," "dilu- 

 vium," " alluvium," etc., for transported material, and " residua," " terra 

 rossa," "gruss," "geest," "saprodite," etc., for the products of rock de- 

 caj'— among laymen and scholars, but none has thus far proved satisfac- 

 tory. Merrill's suggestion is better than any that has gone before, but it 

 remains to be seen whether his term will survive or fall into the ever- 

 yawning grave of desuetude. The author proceeds to classify the regolith 

 as (1) sedentary and (2) transported; the former is subclassed as (a) re- 

 sidual deposits and (6) cumulose deposits, while the latter is divided into 

 (a) colluvial deposits, (6) alluvial deposits, (c) feolian deposits, and {d) 

 glacial deposits. In addition, the soil proper is described, as a product 

 rather than a deposit, with respect to chemical composition, mineral con- 

 stitution, and physical condition, as well as with respect to weight, color, 



