humus because they find it very
rich, and we shall see later on why this is so. Vast areas of such
soils occurring in Manitoba, in Russia, and in Hungary are used for
{37} wheat growing, while there are also areas in the Fen districts of
England.

There is something known as peat that looks rather like mould, but is
really so different that you must be careful not to confuse the two.
Peat is not good for plants, and does not make the soil fertile, but
quite the reverse. You can see it being formed on a moor or bog, and
you should at the first opportunity go and examine it. There was a
peat bog near Wye that was examined with the following results. The
peat was very fibrous and had evidently been formed from plants. It
made a layer about 2 feet thick and underneath it was a bed of clay;
this was discovered by examining the ditches, some of which cut right
through the peat into the clay below. A sample of the clay put into a
funnel, as on p. 14, did not allow water to pass through; this was also
evident from the very wet nature of the ground. The peat bed was below
the level of the surrounding land and was in a sort of basin; the water
draining from the higher land could all collect there but could not run
away, indeed it might very well have been a shallow lake. It was quite
clear that the plants as they died would _decay in very wet soil_, and
so the conditions are very different from those we have just been
studying where the plants _decay in soil that is only moist_. This
difference at once shows itself in the fact that peat generally forms a
thick layer, while mould only rarely does so. In the north of England
the moors lie high, but here again the peat bed is like a saucer or
basin, and there is soil or rock below that does not let the rain water
pass through. For a great part of the year the beds are very wet.

{38}

Look at a piece of peat and notice how very fibrous it is, quite unlike
leaf mould. When it is dry peat easily burns and is much used as fuel
in parts of Scotland, Wales and Ireland. It is cut in blocks during
the spring, left to dry in heaps during summer, and then carried away
in autumn. Fig. 19 shows a peat bog with cutting going on. Peat does
not easily catch light and the fires are generally kept burning all
night; there is no great flame such as you get with a coal fire, but
still there is quite a nice heat.

Peat has a remarkable power of absorbing water. Fill an egg-cup wit