74 
THE FERN FORESTS OF 
It may be asked, how any clew can be found 
to phenomena so evanescent as those of clouds 
and moisture. But do we not trace in the old 
deposits the rain-storms of past times ? The 
heavy drops of a passing shower, the thick, crowd- 
ed tread of a splashing rain, or the small pin- 
pricks of a close and fine one, — all the story, in 
short, of the rising vapors, the gathering clouds, 
the storms and showers of ancient days, we find 
recorded for us in the fossil rain-drops ; and when 
we add to this the possibility of analyzing the 
chemical elements which have been absorbed into 
the soil, but which once made part of the atmos- 
phere, it is not too much to hope that we shall 
learn something hereafter of the meteorology 
even of the earliest geological ages. 
The peculiar character of the vegetable tissue 
in the trees of the Carboniferous period, contain- 
ing, as it did, a large supply of resin drawn from 
the surrounding elements, confirms the view of 
the atmospheric conditions above stated ; and 
this fact, as well as the damp, soggy soil in which 
the first forests must have grown, accounts for 
the formation of coal in greater quantity and 
more combustible in quality than is found in the 
more recent deposits. But stately as were those 
fern forests, where plants which creep low at our 
feet to-day, or are known to us chiefly as under- 
brush, or as rushes and grasses in swampy 
