38 On the Delta and Alluvial Deposits of the Mississippi. 
geographical revolutions in the position of land and sea. The 
lapse of ages, implied by the distinctness of the fossils of the 
eocene, cretaceous, carboniferous, and: other strata, is such, that, 
were we to endeavor to give an idea of it, we must estimate its 
duration, not by years, as in the case of the delta, but by such 
units as would be constituted by the interval between the be- 
ginning of the delta and our own times. “ It is now fifty years,” 
said Mr. Lyell, “since Playfair, after studying the rocks in the 
neighborhood of Edinburgh, in company with Dr. Hutton and 
Sir James Hall, was so struck with the evidence they afforded of 
the immensity of past time, that he observed, ‘ How much farther 
n may go, than imagination can venture to follow!’ These 
views were common to the most illustrious of his contemporaries ; 
and since that time have been adopted by all geologists, whether 
their minds have been formed by the literature of France, or of 
Germany, or of Italy, or Scandinavia, or England ;—all have 
arrived at the same conclusion respecting the great antiquity 
of the globe, and that, too, in opposition to their earlier prepos- 
sessions and to the popular belief of their age. It must be con- 
fessed that, while this unanimity is satisfactory as a remarkable 
test of truth, it is somewhat melancholy to reflect, that, at the 
end of half a century, when so many millions have passed through 
our schools and colleges since Playfair wrote that eloquent pas- 
sage, there is still so great a discordance between the opinions of 
scientific men and the great mass of the community. Had there 
been annual gatherings, such as this, where those who are enti- 
tled to speak with authority, address themselves to a numerous 
assembly, drawn from the higher classes of society, who, by their 
cultivation and influence, must direct the education and form the 
opini 1e many of humbler station, it is impossible that so 
undesirable and unsound a state of things should have now pre- 
vailed as that where there is one creed for the philosopher and 
another for the multitude. Had there been meetings like this, 
even for a quarter of a century, we should already have gained 
for geology the same victory that has been so triumphantly won 
by the astronomer. The earth’s antiquity, together with the 
history of successive races of organic bemgs, would have been 
ere this as cheerfully and universally acknowleged. as the earth’s 
motion, or the number, magnitude, and relative distances of the 
heavenly bodies. I am sure it would be superfluous if I were to 
declare, in an assembly like this, my deep conviction, which you 
—all of you—share, that the further we extend our researches 
into the wonders of creation in time and space, the more do we 
exalt, refine, and elevate our conceptions of the Divine Artificer 
of the Universe.”—Mr. Lyell concluded this discourse by an- 
nouneing his corroboration of the discovery, recently made by 
Dr. King, at Greensburg, thirty miles from Pittsburg, in Pennsyl- 
