498 /Scientific Intelligence. 



presented more in terms of tbe author's opinion than in terms of 

 critical facts of observation. "It does not necessarily follow that 

 the Wakatipu glacier . . . excavated the rock basin in which 

 the lake now lies. We know that the Wakatipu valley existed 

 prior to the glacial period, and there is good reason for the belief 

 that its origin has a close relationship to the powerful faults that 

 traverse each of the main arms of the lake. . . . It is possible, 

 or perhaps even probable, that a lake occupied a part of the floor 

 of the valley before the advent of the ice" (p. 40). On the 

 contrary, the ample breadth of the lake valley and the moderate 

 declivity of its side slopes show that the powerful faults have no 

 close relation to the valley ; and the abundant indications of 

 extensive normal erosion, following the period of mountain fold- 

 ing and preceding the period of glaciation, are strongly against 

 the occurrence of a preglacial lake. 



Furthermore, it is by no means demonstrated that "a valley- 

 glacier with a wide bearing-surface relatively to its depth is 

 incapable of exerting a scooping action"; or that "ice can only 

 excavate its bed when the pressure of its mass exceeds the ulti- 

 mate crushing-strength of the bed rock." Deductions from such 

 postulates as these are not to be trusted. There is unfortunately 

 no sufficient mention of the most critical elements of this problem, 

 namely the form of the lake-valley to-day, which is of much 

 greater value in determining the erosive work done by Pleistocene 

 glaciers than any deductive estimates of glacial erosion can be. 

 Whether glaciers erode their troughs slowly or rapidly, the 

 amount of erosion that they accomplished must be a function of 

 their duration; and as their duration is absolutely unknown, apart 

 from the work that they accomplished, it is better to look at the 

 consequences of their work recorded in their evacuated troughs, 

 than to infer their behavior on theoretical grounds, when the 

 attempt is made to determine what amount of sculpturing they 

 effected. w. m. d. 



2. West Virginia Geological Survey ; I. C. White, State 

 Geologist. Vol. IV. Iron Ores, Salt and Sandstones ; by G. P. 

 Grimsley. Pp. xv, 603 with 24 plates, 16 figures. Morgantown, 

 1909. — This volume illustrates the fact that the geological survey 

 of a state can accomplish important results when the reports show 

 what results may be looked for in the future in undeveloped fields. 

 It is divided into three parts, discussing respectively the iron ores, 

 the salt, and the sandstones, including with the latter the glass sand 

 industry. The production of iron ore, which began in 1800 and 

 continued down until 1880, has now ceased entirely in consequence 

 of the introduction of cheaper ores, particularly from the Lake 

 Superior region. The detailed facts given in this Report show, 

 however, that there are extensive ore deposits, particularly suited 

 for the manufacture of open hearth steel, which are available for 

 development in the future, when transportation conditions are 

 more favorable. What is regarded as a conservative estimate 

 gives 140 million tons as the amount probably available in five 



