ON CLAY 2II 
on the north side of the jetty. Materials thus deposited gradually 
pile up to such an extent as to protect the base of the cliff from 
wave-action. Thus the effect of the slumping of the springtime 
(which tends to reduce the angle of slope) is not fully removed from 
year to year. 
Fic. 158.—The bluff habitats near Glencoe, Ill., showing several stages in the 
development of the forest on the bluff. The area to the right of a line between a and } 
is stable enough to support some sweet clover. Here the tiger-beetle larvae, spider, 
etc., are most abundant. The area between lines joining a and ) and a and ¢ is in the 
early shrub stage. To the left of ac the shrubs are denser and larger, and some trees 
are present. Reprinted from the Journal of Morphology. 
2. SWEET-CLOVER ASSOCIATION 
(Fig. 158) (55) 
Under the condition described above, the water of rainfall, as well 
as the slumping, reduces the angle of slope, and the bluff becomes more 
and more stable. Some of the clods of turf from the top of the bank 
stop half way down the slope. The bluff begins to support a few xero- 
phytic plants, such as the sweet clover, asters, etc. 
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