1922] THONE—STARVED ROCK 357 
of species able to get an early start or make sufficiently rapid 
growth to have well established root systems before the advent of 
the usual summer droughts. 
A more detailed examination of individual stations serves to 
emphasize the facts already noted in general, and also brings out 
several edaphic phenomena of considerable interest. It is here 
that topograph factors appear to function. Thus, station 1 is the 
least exposed, and also the least well drained, being on the flat 
floor of a canyon. It is also subject to flooding when there is 
heavy rain, and the run-off from the tributary gullies comes over 
the canyon falls. It is not surprising, therefore, to find that it is 
constantly well above both the wilting coefficient and the Livingston- 
Koketsu wilting point. It is not surprising, either, to find here the 
largest number of young seedlings, and a herbaceous vegetation 
dominated by annuals. On the other hand, the highest upland 
station, no. 7, is both well drained and quite exposed; in correlation 
therewith it rapidly loses what water it gains, and persistently 
holds a place near the bottom of the column during the droughty 
periods. Few seedlings develop, and the herbaceous vegetation 
consists largely of grasses and sedges and of perennating prairie 
plants. The stations on the more or less sloping terrain (no. 6 on 
the upland and nos. 5, 3, and 2 on talus slopes) present phenomena 
intermediate between these extremes. 
Station 4, on an alluvial flat beside the river, in a maple-elm-ash 
association, presents an anomalous situation. Starting in the 
spring with a moderate amount of soil water, it loses rapidly and 
fails to recover, during the summer rains, to anything like the 
degree displayed by the other stations. The soil point data con- 
firm its bankruptcy. After it has lost its water during June, it 
falls to the bottom of the heap during the droughty periods and 
stays there more persistently than any other station. During the 
rains, when the others rapidly increased in their water-supplying 
power, this station rose but little, and then quickly dropped to the 
bottom again. This behavior may be accounted for in several 
ways. The soil here is a heavy, silty alluvium, very tenacious of 
the water it gets. It does not receive the benefit of periodic 
flooding, as does station 1. The thicket of saplings is so dense that 
