182 
THE TERTIARY AGE, AND 
Oranges, Bananas, etc., the shade- and cluster- 
trees, so important to the comfort and shelter of 
man, are added to the vegetable world during 
these epochs. The fossil vegetation of the Terti- 
aries is, indeed, most interesting from this point 
of view, showing the gradual maturing and com- 
pletion of those conditions most intimately associ- 
ated with human life. The earth had already its 
seasons, its spring and summer, its autumn and 
winter, its seed-time and harvest, though neither 
sower nor reaper was there ; the forests then, as 
now, dropped their thick carpet of leaves upon 
the ground in the autumn, and in many localities 
they remain where they originally fell, with a 
layer of soil between the successive layers of 
leaves, — a leafy chronology, as it were, by which 
we read the passage of the years which divided 
these deposits from each other. Where the leaves 
have fallen singly on a clayey soil favorable for 
receiving such impressions, they have daguerro- 
typcd themselves with the most wonderful accu- 
racy, and the Oaks, Poplars, Willows, Maples, 
valnuts, Gum- and Cinnamon-trees, etc., of the 
Tertiaries are as well known to us as are those of 
our own time. 
It was an eventful day, not only for science, 
but for the world, when a Siberian fisherman 
chanced to observe a singular mound lying near 
the mouth of the River Lena, where it empties 
