390 H. FOSTER BAIN 



1896. In the spring of that year he undertook to put into shape 

 long-accumulated notes on Johnson, the county in which Iowa 

 City is situated. It chances that two lobes of Iowan drift reach 

 across the northern border of this county. South of these lobes 

 are the loess hills characteristic of much of the Iowan border and, 

 in turn, the broad loess-Kansan plains. At that time the southern 

 boundary of the Iowan had not been traced. From the known 

 presence of two drifts at Afton and elsewhere in southern Iowa, 

 it had been inferred that the Iowan boundary was much farther 

 south than now appears true. The battle for two ice-sheets has 

 been but too recently won to encourage belief in many. Calvin, 

 however, intimately familiar with the typical Iowan drift plane of' 

 Buchanan and Delaware counties, recognized at once that the phe- 

 nomena of southern Johnson County required a new interpretation, 

 and shortly thereafter hit upon the clue. The rest of the staff, 

 inspired by his enthusiasm, started out like crusaders to over- 

 turn and rebuild the Pleistocene column. The field was particu- 

 larly favorable since in Iowa the different drift sheets are mainly 

 deployed rather than superimposed, and since, also, nearly the 

 whole sequence is represented. With the kindly counsel of T. C. 

 Chamberlin, with friendly visits from R. D. Salisbury, J. E. Todd, 

 Albrecht Penck, Frank Leverett, and others, the work went 

 rapidly. There were many field conferences, and the winter meet- 

 ings of the Iowa Academy of Science became notable for the dis- 

 cussion of current Pleistocene problems. Naturally there were 

 differences of opinion and later work has shown the need of some 

 revision of first-stated conclusions. Out of it all, however, has 

 come the recognition of the independence of the pre-Kansan, the 

 thorough establishment of the Aftonian, and the concept of the 

 Iowan ice sheet. As to the latter, especially, there has been, and 

 still is, much difference of opinion. The Iowan drift is so peculiar, it 

 is so local, and the phenomena are so puzzling, that some find them- 

 selves unable to accept the evidence of its existence. It is not 

 my purpose to review the proofs. That has already been done 

 most excellently by Calvin himself. It is sufficient to repeat here 

 a remark made by him at the close of the first field season devoted 

 to this study: "The Iowan ice sheet did so many queer things that 



