The Field of Geology— McGee. 197 



countries; and most of the mines of the world have been exten- 

 sively exploited. Yet the progress in this field of rock formation 

 has thus far been chiefly in the direction of differentiation and 

 endless multiplication of details; and the need of the hour is for 

 concentration and for the development of a philosophic idea by 

 which the complex subject may be simplified as the even more 

 complex subject of biology was simplified by the idea of natural 

 selection. This field of geology is promising both to the daily 

 drudge who digs for base metal and to the inspired searcher who 

 delves more deeply for the golden grains of knowledge. 



It is remarkable that the class of geologic processes and agen- 

 cies most intimately related to the leading industry of the world, 

 and even with all the higher forms of life upon the globe, i. e., the 

 decomposition of rocks, the formation of subsoils and soils, etc., 

 should have received so little attention. The entire field of agri- 

 cultural geology remains practically untrodden, and no man dreams 

 whither its unexplored paths may lead. 



Although the glacial deposits of the world, and particularly 

 those of America, have been elaborately studied, and although this 

 study has contributed more than one important chapter to the 

 history of the earth's development, the field remains fertile and 

 yields rich returns for labor expended upon it. But little is yet 

 known of the destructive action of ice; for the glacial mill is veiled 

 from curious eyes, save perhaps its outer portals, and the areas of 

 greatest grinding are unexplored or inaccessible; the fact that, the 

 question as to the glacial excavation of the Great Lakes is still 

 mooted and so far from settlement that no conservative geologist 

 speaks upon it with confidence, well illustrates the paucity of 

 knowledge concerning the primary process of glaciation; and so 

 this field is one of the most promising within the domain of the 

 science to the intrepid explorer. Equally promising however, is 

 the general field of inquiry concerning the causes and conditions 

 of glacial climate, where the physicist and astronomer meet the 

 geologist on common ground, and where more than one sturdy 

 pioneer has already gone down beneath the gloom of uncertainty 

 into the treacherous morass of ill-founded speculation. 



The direct action of the winds has never been an important 

 process in geology, save, perhaps, in limited areas, and the subject 

 promises little to the investigator; the indirect action of the winds 

 through the waves and currents of inland seas has just been studied 



