Species 



Lower 

 Contact 

 6 inches 



4 inches 



2 inches 



Upper 

 Contact 



Pmus 



Strobus and 

 p. rcsmosa 





^ 



^ 





p 

 fianksiana 











Picea 

 glauCQ 









^ 



R 

 mariana 











Abies 

 canadensis 











Beta a sp. 











Quercus sp. 











Acer sp. 











"Hlia 

 americana 











Figure 1. Graphs showing percentages of tree-pollens in a Pre-Kansan peat 

 deposit near Belle Plaine, Iowa. The height of each rectangle represents 



eighty percent. 



