40S Scientific Intelligence. 



13. Structural and Field Geology ; by James Geikie. P|>, 

 xx + 435, 56 page plates, 142 text illustrations. New York, 

 1905 (D. Van Nostrand Co.). — This volume opens by describing 

 the rock-making minerals, also the rocks and fossils in so far as 

 they are related to structural geology. Following this are 

 several chapters on the rock structures, such as stratification, 

 faults, mode of occurrence of eruptive rocks and of ore forma- 

 tions. A third part deals with the principles of geological sur- 

 veying and the economic aspects of geological structure. The 

 work is made very attractive by clear typography, appropriate 

 subdivisions, and by the number and excellence of the illustra- 

 tions, taken almost entirely from the British Isles, the plates 

 being photographic reproductions. In photographing the rock- 

 types, however, there is a tendency to unnaturally heighten the 

 color contrasts. 



Within the limits indicated by the title this is an excellent 

 treatise, the subject matter being well arranged and classified. 

 The chief value is for its outdoor application, the student finding 

 here a good discussion of field methods and a full description 

 of the structures which he is to look for and identify. The 

 subordination of the dynamical to the structural side results 

 necessarily in the causal relations of earth structures and their 

 interpretation from being made prominent. The ultimate sig- 

 nificances of the geological facts are thus not well brought out, 

 and as these are the highest significances they should not be lost 

 sight of in geological instruction. However, as the volume does 

 not profess to cover this side of the subject, it should not be 

 urged as a criticism but should merely be called to the attention 

 of educators as not supplying the whole of the inorganic side of 

 the science. As a text-book presenting an excellent account of 

 the facts and field methods upon which geological conclusions 

 are based, it is of value to all students of pure or applied 

 geology. J. b. 



14. The Clays and Clay Industries of Connecticut; by Gerald 

 Francis Lotjghlln. Bulletin No. 4 Connecticut Geol. and 

 Natural History Survey. Hartford, Conn. 121 pp., 13 maps 

 and plates. 1905. — This report gives first the geographical 

 distribution of the Connecticut clays, followed by a discussion 

 on the origin of clays in general and the geological history of 

 the Connecticut clays in particular. It is shown that they were 

 laid down in quiet waters fronting the continental glacier toward 

 the close of the glacial period. The gravels, sands and clays 

 give indications of water levels at 180, 120 and 80 feet above 

 the present level of the sea. The writer ascribes the highest of 

 these to damming by fragments of ice still lingering to the 

 south, as the highest indication of shore lines to the south is only 

 120 feet above sea level. But in view of Fuller's recent paper 

 on the Geology of Fisher's Island,* the reviewer suggests as not 

 improbable that these high-level gravels and clays may mark a 



* Bull. Geol. Soc. Anier., vol. xvi, pp. 367-390, 1905. 



