hich has accumulated in
this manner is thin, therefore everywhere penetrated by the fibrous
roots of the moss, it may continue to cling to its sloping bed; but
when it attains a considerable thickness, and the roots in the lower
part decay, the pulpy mass, water-laden in some time of heavy rain,
break away in a vast torrent of thick, black mud, which may inundate
the lower lands, causing widespread destruction.

In more southern countries, other water-loving plants lead to the
formation of climbing bogs. Of these, the commonest and most effective
are the species of reeds, of which our Indian cane is a familiar
example. Brakes of this vegetation, plentifully mingled with other
species of aquatic growth, form those remarkable climbing bogs known
as the Dismal and other swamps, which numerously occur along the coast
line of the United States from southern Maryland to eastern Texas.
Climbing bogs are particularly interesting, not only from the fact
that they are eminently peculiar effects of plant growth, but because
they give us a vivid picture of those ancient morasses in which grew
the plants that formed the beds of vegetable matter now appearing in
the state of coal. Each such bed of buried swamp material was, with
rare exceptions, where the accumulation took place in lakes, gathered
in climbing bogs such as we have described.

Lake bogs occur in all parts of the world, but in their best
development are limited to relatively high latitudes, and this for the
reason that the plants which form vegetable matter grow most
luxuriantly in cool climates and in regions where the level of the
basin is subject to less variation than occurs in the alternating wet
and dry seasons which exist in nearly all tropical regions. The
fittest conditions are found in glaciated regions, where, as before
noted, small lakes are usually very abundant. On the shores of one of
these pools, of size not so great that the waves may attain a
considerable height, or in the sheltered bay of a larger lake, various
aquatic plants, especially the species of pond lilies, take root upon
the bottom, and spread their expanded leaves on the surface of the
water. These flexible-leaved and elastic-stemmed plants can endure
waves which attain no more than a foot or two of height, and by the
friction which they afford make the swash on the shore very slight. In
the quiet water, rushes take root, and still further protect the
strand, so that the very delicate vege