à 
1877.] The Age of this Earth. 293 
been added to and taken away. In these subtractions he sees 
the fossil remains of prehistoric organic structure torn from their 
resting-places in the calcareous rocks, he handles the flint nodule 
formed from the silicious dusts of diatoms and foraminifera, and 
finds the same dusts in course of deposit in the deepest parts of 
the ocean, telling him, not only that these organisms have contin- 
ued their races for millions of years, but that they have, for all 
those ages, left their dusts to subside upon the ocean bed, certain 
evidence that the site on which we find the stratified caleareous 
rocks, with their lines of flint nodules, was once the ocean bed.. 
He may look on the sand collections now on our surf-beaten 
shores, on the wind-drifts of the great deserts, and on the sand- 
dunes in many regions; he does not know when they began to 
grow, but he sees on mountain sides sandstone rocks several hun- 
dred feet in thickness, many miles in length and breadth. He 
knows that they were formed and gathered by the same forces 
that now occupy hundreds of years in adding a few inches to the 
shores, and he is lost in thinking of the vast amount of silicious 
matter broken up, triturated into sand, and deposited by the 
water on its bed, and that bed hundreds of feet above his head. 
He finds the hard silicious rock in stratified form on the tops of 
our highest mountains, in their interior, and in the deepest seas, 
where it still wears away and contributes atoms for deposit in 
other places. He is lost in the time oceupied by the deepening 
of the sea, by the vastness of the deposits formed by it, far above 
its present surface level, and by the extent of deposit now in 
progress in its depths. The geographer knows that every river 
is always bringing something to its estuary, yet its growth of 
dry land is very slow; he measures it, but he cannot tell by that 
measurement when the estuary of the Nile was four thousand 
miles from its present site. He may trace the Mississippi from 
its present watery delta back to its tributaries in the Rocky 
Mountains, but it does not tell him when these, now great, 
waters trickled as little rills from the first dry land of those 
regions. He looks upon the water-worn chasms of the Himalayas 
and the Alps, on the vast gorges of great rivers; he cannot say 
when those rivers began to run, or how long it took them to 
wear away the hard obstruction to their course, any easier than 
Sir Charles Lyell could tell the age of the Niagara Gorge. 
e may see the vast structure of the coral insect [sic] now 
growing over thousands of miles in the Red Sea, but he does not 
know when those structures were commenced. He sees the stu- 
