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A. Skokie Marsh. 
(Plate VI.) 
A strip of low, marshy land, about one mile in width, through 
which a small stream flows in the spring and early summer. In 
late summer and fall this stream is reduced to a series of pools sepa- 
rated by dry land. The marsh, which is covered with water from 
a few inches to several feet in depth in spring, becomes dried out 
in the fall and the ground becomes hard and sun-cracked. The 
marshy area is open, for the most part, and is covered with a thick 
growth of cattails and other aquatic vegetation, while toward the 
margins a tall, thick growth of swamp grass (Calamagrostis) suc- 
ceeds the reeds. The marsh is dotted here and there with many 
small “islands”? composed of several species of marsh-loving trees 
(see Fig. 1). These “islands” are surrounded by a dense growth 
of cattails, which attain a height of over ten feet and are very 
difficult to penetrate. The Glencoe road crosses the marsh, and 
on either side a rather deep ditch has been made, which is filled 
with aquatic plants. In two places these ditches form a large, 
deep, circular basin, connecting the ditches and spanned by a low 
bridge. The stream also widens as it flows under the Glencoe road 
bridge, forming a wide, deep pool. In the fall these ditches become 
more or less dry, and the basins are reduced to small pools. 
B. Intermediate Ridge or Sand Spit. 
A triangular piece of territory about a mile wide, lying west of 
the Skokie Marsh. The ground is from ten to twenty feet above 
the surface of the stream and is well wooded for the most part. The 
slope on the eastern face of this ridge is very gradual, but on the 
west it 1s quite abrupt, forming a rather steep terrace bordering 
the East Branch of the Chicago River. Scattered throughout this 
area are numerous depressions of various sizes, from a few feet to 
two hundred feet or more in diameter. These are of varying depth, 
‘from a few inches to several feet. In the spring they are filled with 
water and support a varied fauna and flora, but in the summer 
they dry up wholly or partially. These may be termed summer-dry 
ponds or pools—a name which seems more comprehensive than the 
word swale, which is used in the eastern states. About a dozen 
