Geology and Mineralogy. 409 



deepest stage of the Champlain submergence. If so they are of 

 considerable scientific importance as serving to correlate the 

 stages of ice retreat with the several stages of the Champlain 

 subsidence within the New England states. Having given the 

 geographical distribution and origin of the Connecticut clays, 

 the subject is taken up of the chemistry of clays, the physical 

 properties of clays and their commercial classification. Follow- 

 ing this the composition, properties and adaptabilities of the 

 Connecticut clays are given in detail. The lacustrine and 

 estuarine clays, embracing the bulk of the clay deposits, while 

 suited for the best quality of common red brick at low expense, 

 are limited in their uses by high percentage of iron and ex- 

 tremely low fusing point. Part II treats of the clay industries 

 of Connecticut. 



The bulletin is well written throughout and is adapted to the 

 comprehension of the intelligent but untechnical reader. The 

 limited time and money appropriated for this work prevent it 

 from being a final study of the subject, as noted in the introduc- 

 tion. Yet the results are of very considerable value, and by 

 calling attention to one of the resources of the state which is, at 

 present, but poorly developed, may ultimately yield a return in 

 industry many times the comparatively small expenditure re- 

 quired for this report. j. b. 



15. Geology of Western Ore Deposits ; by Arthur Lakes, 

 late Professor of Geology at the Colorado School of Mines, 

 438 pp., 300 illustrations. Denver, Col. (The Kendrick Book 

 and Stationery Co.) — This volume is not written for the specialist 

 but for the intelligent miner or other person interested in the 

 subject of western ore deposits. Introductory chapters review 

 the rock-making, minerals, the ore minerals, and the features of 

 structural and dynamical geology connected with ore deposits. 

 A glossary and index serve a useful purpose. The principles of 

 ore deposition and various types of ore deposits are treated, the 

 examples being chiefly drawn from Colorado, with which state 

 the writer is most familiar, but the mining districts of the other 

 western states and of Alaska are also briefly reviewed, and the 

 distinctive features indicated. j. b. 



16. The Delavan Lobe of the Lake Michigan Glacier of the 

 Wisconsin Stage of Glaciation and Associated Phenomena; by 

 William C. Alden. 106 pp., 15 plates. Washington, 1904. 

 Professional Paper No. 34, IT. S. G. S. — The author presents in 

 this paper the detailed results of several seasons field work in 

 the southeastern part of Wisconsin on a small tributary lobe of 

 the Lake Michigan glacier. The points of chief interest lie in 

 the proof, based on interlobate phenomena, of the contempora- 

 neity of the Lake Michigan, Delavan, and Green Bay ice lobes 

 and the simultaneous withdrawal of the two latter from their 

 terminal moraines ; and in the application to the deposits in this 

 field of the criteria for the determination of the age relationships 

 of the Wisconsin and pre- Wisconsin drift. 



