A PIECE OF COAL. 187 
miles long and twenty-five broad. The whole place is 
one enormous quagmire, overgrown with water-plants 
and trees. The soil is as black as ink from the old, 
dead leaves, grasses, roots, and stems which lie in it; 
and so soft, that everything would sink into it, if it 
were not for the matted roots of the mosses, ferns, 
and other plants which bind it together. You may 
dig down for ten or fifteen feet, and find nothing 
but peat made of the remains of plants which have 
lived and died there in succession for ages and ages, 
while the black trunks of the fallen trees lie here 
and there, gradually being covered up by the dead 
plants. 
The whole place is so still, gloomy, and desolate, 
that it goes by the name of the " Great Dismal 
Swamp," and you see we have here what might well 
be the beginning of a bed of coal; for we know that 
peat when dried becomes firm and makes an excellent 
fire, and that if it were pressed till it was hard and 
solid it would not be unlike coal. If, then, we can 
explain how this peaty bed has been kept pure from 
earth, we shall be able to understand how a coal-bed 
may have been formed, even though the plants and 
trees which grow in this swamp are different from 
those which grew in the coal-forests. 
The explanation is not difficult; streams flow con- 
stantly, or rather ooze into the Great Dismal Swamp 
from the land that lies to the west, but instead of 
bringing mud in with them as rivers bring to the sea, 
they bring only clear, pure water, because, as they 
filter for miles through the dense jungle of reeds, 
ferns, and shrubs which grow round the marsh, all 
