, 
tgor] PHYSIOGRAPHIC ECOLOGY OF CHICAGO 167 
rubra and Q. coccinea tinctoria). Fig. 32 shows a tree-clad cliff’ 
in which most of the above trees are to be found. 
Whether a mesophytic forest would develop on a lake bluff 
is something of a question. It seems likely that semi-xero- 
phytic trees will dominate there for a long time to come on 






Fic. 31.—Sea cliff at Glencoe, at a place where lake erosion has ceased. Shrubs 
(largely celiat and willows) prominent as well as herbs. Absence of lake erosion 
also indicated by the e gentle slope, as compared with fg. 70. The leaning oak at the 
top bears wie to former erosive forces 
account of the xerophytic atmospheric conditions. Particularly 
at the top of the bluff do the conditions remain severe, by 
reason of the great exposure and also the dryness of the soil. 
If the lake should recede for some distance, a mesophytic forest 
could certainly develop on the bluff before it is reduced to any- 
thing like the common level. This is shown onthe ancient lake 
bluff at Beverly hills. Here there is an old cliff about forty 
