THE STATUS OF PALEOBOTANY 175 



systematic paleobotanical-geological study of our northern peat 

 bogs and old forest grounds would be most timely. Such a study 

 would not only yield a large body of purely botanical informa- 

 tion but would serve to establish a rational chronology with 

 respect to the various advances and retreats of the ice sheets, 

 would throw much light on the attendant physical and climatic 

 conditions and would furnish a sound foundation for the study 

 of modern plant distribution. 



For example such a study ought to furnish data for determining 

 whether secular cooling was a factor in causing advancing ice 

 sheets and if not to what extent the influences of the continental 

 glaciers was felt many miles south of the terminal moraines. 

 There is some evidence that there was but slight if any lowering 

 of temperatures in low latitudes, but until the chronology of 

 events and the correlation of deposits is perfected we cannot 

 know whether our southern Pleistocene floras were contempor- 

 aneous with the advances of the continental ice sheet or corre- 

 spond to interglacial periods. 



Such a study would not only open the way for the consideration 

 of numerous subsidiary problems that would be sure to be raised, 

 but it would enable us to determine the antiquity of numerous 

 elements in the existing flora, the extent and" perhaps the rate 

 of their migrations, which in turn ought to furnish the key to 

 the solution of numberless problems of geographic distribution 

 and the influence of physiography upon ecology. It would also 

 contribute data for estimating the part which certain edaphic 

 factors, such as the increased physical and chemical complexities 

 of soils due to ice action, had in the evolution of new forms, as 

 well as the part taken by increased competition in lower latitudes 

 in the van of advancing ice sheets and the reversal of conditions 

 with their retreat. 



We owe it to the rest of the world to do our duty by our native 

 continent. Some sort of systematic attack should be made upon 

 this problem, in which cooperative work would possibly be 

 desirable. 



