166 BOTANICAL GAZETTE [MARCH 
character ; at the top there can be seen overhanging turf, giving 
evidence both of the destructive action of the lake and also of 
the tenacity with which a grass mat holds its place in the pres- 
ence of adverse conditions. Near the center of fig. 3z may be 
seen a white oak which was almost overthrown by the erosive 
activities, but which has been preserved through the cessation 
of erosion at this point. The gully shown near the center of 
jig. 30 is seen in closer view in fig. 7; the absence of vegetation, 
save that which has slid down from above, is very striking. 
If for any reason the lake activities at the base of the cliff 
are stopped, an opportunity is offered for the development of 
vegetation. At Glencoe the cliff erosion has been checked to 
some extent by artificial means, and one can see various phases 
of cliff life within a small area. When the erosion at the base 
of the bluff ceases, conditions become much more stable, though 
landslide action may still occur. In time the slope gradient 
becomes so low that the cliff soil is essentially stable ; when this 
time arises vegetation develops with great rapidity in spite of the 
xerophytic conditions which are still as pronounced as before. 
It is very obvious, therefore, that it is the instability of the 
eroding cliff and not its xerophytic character which accounts 
for the absence of plant life. 
The first vegetation is commonly made up of xerophytic 
herbs, both annual and perennial. Among these are the sweet 
clover (Melilotus alba), various annual weeds, various species of 
aster, especially A. laevis, Equisetum hyemale, various grasses, 
etc. oon there develops a xerophytic thicket vegetation, 
such as is shown in fig. 37. This may be called the shrub stage 
of the captured cliff, and among the dominant species are the 
juniper and cedar (Funiperus communis and ¥. Virginiana), Salix 
Slaucophylla, the osier dogwood (Cornus stolonifera), Shepherdia 
Canadensis, various sumachs (Rhus. typhina and R. glabra). The 
following tree stage is dominated by various poplars (Populus 
tremuloides, P. grandidentata, P. monilifera), the hop hornbeam 
(Ostrya Virginica), the white pine (Pinus Strobus), the red cedar 
(Funiperus Virginiana), and some of the oaks (probably Quercus 

