EDITORIAL 875 



The completion of the nomenclature by the naming of the 

 intcro-lacial deposits is desirable, but it is doubtful whether it 

 can be satisfactorily done at present. The correlation of the 

 Toronto beds with the Mississippi series seems to me to remain 

 uncertain, but they are so preeminently fitted to give name to 

 their horizon that it seems best to reserve for them the place to 

 which they most probably belong. Some of the known vegetal 

 deposits found below the lowan till sheet could appropriately 

 o-ivc name to the interglacial deposits between the Iowa and Illi- 

 nois beds if their horizon could be positively fixed, but it cannot 

 now be stated certainly whether the interval marked by these is 

 that between the lowan and Illinois sheets, or that between the 

 Illinois and Kansan sheets. The Buchanan gravels are regarded 

 by Professor Calvin as marking the initial stages of the interval 

 following the formation of the Kansan drift, and the term 

 Buchanan has been employed by him in designating this interval. 

 The probable close connection between the formation of these 

 gravels and the underlying drift renders the name something 

 less than ideal as the designation of true interglacial deposition, 

 but the pronounced characteristics of the formation and its 

 great significance, joined to its excellent exposure and easy 

 accessibility, make it doubtless the best nominative deposit now 

 available. 



While returning from my last visit to the field in which the 

 Kansan, Illinoian, lowan, and Wisconsin formations were seen in 

 close succession, I made a memorandum of impressions respect- 

 ing their relative ages simply as a means of comparison with 

 judgments formed at other times, the impressions being derived 

 from the respective degrees of erosion and chemical change 

 which the formations have undergone. Although this was 

 intended to be nothing more than a record of passing impres- 

 sions, it may be the best means of giving some notion of my 

 rating of the historical importance of the formations. Taking the 

 interval from the late Wisconsin deposits (as found immediately 

 south of the Great Lakes) to the present date as unity, the fol- 

 lowino; is the memorandum: 



