THE LAKES OF IOWA,—PAST AND PRESENT. 147 
cut; yet all except two, one in Wright county, and the 
other in Sac county, Iowa, seem never to have’ been favored 
with the visits of an imaginative writer to tell fanciful stories 
of their associated remains of human handiwork. 
It seemed necessary to make the foregoing statement of 
facts, and’ the geological principles which they involve, be- 
fore attempting a description of the lakelets themselves, that 
such a description might thus be rendered more intelligible, 
and which is here given’ as the result of long-continued 
observation of sixteen such lakelets in Northern Iowa, in- 
cluding the two which have become noted as walled lakes. 
They usually occupy an open prairie region. Sometimes 
small groves are near them, but trees are often entirely 
wanting, especially since’ the settlers mercilessly destroy 
them for fuel. They are from one to five miles across, but 
always very shallow, because the undulations within which 
they rest are very gentle. None of them are more than 
fifteen feet deep, and the majority are so shallow that they 
permit a luxuriant growth of wild rice and other aquatic 
Plants from their bottoms over the whole, or a large part of 
eir areas, among which water-fow! find shelter and abun- 
dant food, but which renders them rather uninteresting fea- 
tures of the landscape. 
A true description of the so-called walls, but which we 
shall term embankments, will be best understood if given in 
connection with a description of their origin. When a pile 
of sand, obtained from the river shore, has been left by the 
Workmen for a long time exposed to the washings of the 
rains, the gravel which it contains, and which at first is 
hardly visible, becomes in some cases even more conspicuous 
than the sand itself, because a part of the latter has been 
Wasted, while the gravel remains. Thus it has been upon 
an extended scale with the drift, which, as before stated, is 
Composed of bowlders, gravel, sand, clay, and soil, although 
little except the latter is usually seen upon the prairie sur- 
faces. Sometimes the drift is more than a hundred feet 

