24 KANSAS ACADEMY OF SCIENCE. 
disclosed the fact that it had been built 18 years before. The cementing ma- 
terial in which these stones were laid must have been of an exceedingly good 
quality, and the builders must have perfectly understood the art of laying them 
up in that unique fashion. Except upon the sills and lintels no mark of tool other 
than that of trowel upon the mortar was noticeable upon the walls. Indeed 
these pebbles are so hard as to almost defy any tool to work them info shape. 
My object in describing such buildings and fences is not merely to show the 
thrift of the people, but to show the abundance of the drift material, where se- 
lections of so many stones, uniform in size, color, and shape, may be made. 
Lakes anD MaRSHES. 
Nearly everywhere, in the hollows among these drift hills and on vhe low 
grounds where the hills do not exist, there are small lakes and numerous marshes. 
The marshes have the appearance of having at one time been lakes. Sometimes 
the marshes are mere circular belts of marsh surrounding small lakes that are 
continually growing smaller and smaller. In a few places the marshes have en- 
tirely overgrown the small lakes; and near the middle, where they have not be- 
come entirely solid, a pole 20 feet long may be pushed down through the marsh 
into the underlying lake, which has not yet filled up below; in other places where 
the lake is not yet closed, the edge of the marsh extends out over the lake quite 
thinly, and in such a way as to overhang the water, often to a considerable dis- 
tance. By standing on the ground in one spot, and dancing lightly, the surface 
all around for some little distance may be made to vibrate; and if one were to 
continue the dancing or vibratory movement he would sink into the soft black 
muck entirely out of sight. Cows and horses often sink so they are unable to 
extricate themselves. They are then said to be ‘ mired.” 
Not all lakes have marshes surrounding them. Sand-bottomed lakes are not 
surrounded by marshes, but the water washes the clean hard shore; mud lakes 
too are seldom surrounded by marshes; but the lakes, whose bottoms are com- 
posed of a hard impervious clay, and which have, as nearly all lakes have, small 
sluggish outlets, are almost invariably surrounded by marsh. Marshes (that 
have grown over shallow lakes have rapidly covered the entire lake and have 
caused the lake to disappear. The growth of marsh ovet the edge of deeper 
lakes, those reaching to a depth of 15 feet and upward, is very slow; and on a 
lake with a depth of 30 feet the marsh around its edge is scarcely seen to make 
any progress. 
A recent visit to the home of my childhood has shown me what appears to be 
a surprising reduction in the size of those lakes. Naturally, a 30 years’ absence 
would make the lakes appear very much smaller; but that it is not ali a personal 
difference may be readily seen when the structure of those marshes is taken into 
account. The tall grass growing on the edge of the marsh next to the water, 
when it decays, largely overhangs the edge into the water, where it is held in 
place by the growing rootlets of the grass, until, after the lapse of many years, a 
perceptible thickness must be added to the extending edge of the marsh. The 
growth and extension of marsh is more rapid than the wear of the edge by the 
wash of the waves, which is scarcely anything. Again, the growth of pond-lilies 
and other water plants in the shallows rapidly hastens the extension of marsh 
and ‘the closing of the lakes by allowing a slight deposit on their floating leaves, 
to be followed by an interwoven mass of vegetation which permits the accumula- 
tion’of vegetable mold and humus. Extension of marsh under such conditions 
is many'times more rapid than where the water is deep. Extension of marsh 
over a deep lake may be estimated at one thirty-second to one-twelfth of an inch 
annually. This would equal a growth of one foot horizontally toward the center 
