256
THE ESSEX NATURALIST
dead; and the natural condition of a normal valley is swampy,
especially in a wet season. For these reasons, the land was for-
merly charged to the full with water, springs ran strongly, and the
rivers must have been large, of lower average velocity and often
indeterminate as to their exact margins. The development of the
country for farming purposes caused many ditches to be dug
around the fields for the better drainage of the land without which
the crops could not be grown; and, in total, this has resulted in
surface water being conveyed from uplands to the valleys far more
rapidly than heretofore. In the valleys themselves men cut chan-
nels through swamps to drain the land, thereby altering the nature
of the soils, so that in place of a fen, with its marshy vegetation,
they obtained conditions suitable for meadows bearing rich grass.
Again, the net effect on the surface water was to dry out the soil
and sub-soil, and to accelerate flow to the river. Thus, we arrive at
the condition in which such a river as the Lee existed some 100 or
150 years ago. In place of large tracts of thick forest, penetrated by
wet, swampy valleys, there existed wide areas of arable farm land
(interspersed it is true with a certain area of woodland, whether
planted or surviving from an earlier forest), and drained by rivers
of quite moderate width, flowing through grassy meadow land. In
times of heavy rain or of melting snow, the rivers would tem-
porarily be overwhelmed, and a flood would make its way down
the valley. Such conditions frequently obtain in the upper reaches
of the Essex rivers where they flow over clay, but are becoming
rarer in the chalk streams of Hertfordshire.
Provided that such floods do not seriously interrupt communi-
cations, and provided they are free to travel down the valley and
are not caused to pond up unnecessarily, such seasonal floods do
no great harm to certain classes of agriculture; the reverse in fact.
A fine silt is usually brought down by such a flood, and provided
the water is run off the valley meadows after a day or two, the
grass is all the better for it. Such a phenomenon is the mild and
small English equivalent of the rich alluvial-bearing floods of the
Nile Valley. In the past, for want of the necessary finances and
concerted action, people suffered such floods a great deal more
than was desirable; but it should be emphasised that a flood of
short duration is not a curse, but may be a blessing. The chief
troubles here arise from ignorant action, taken by people, princi-
pally in the past century, which has radically upset the regime of
the rivers.
THE USES OF RIVERS
Man has used, and is still using, rivers for several different
purposes. Sometimes these uses harmonise—sometimes quite the
contrary; and a student of history will find endless examples of