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to prove that they are utterly repugnant. If I only succeed 
in convincing you, that neither the one nor the other ought to 
be absolutely accepted as “ scientific truth,” at least without 
further inquiry, I shall have done enough. For it is only our 
duty, you may remember, “ simply to hear and believe,” — 
“ when all the professors in the world announce a certain 
order of Geological succession !” 
It is the fashion now, as we very well know, among a 
certain class of scientific men, to deny that some great con- 
vulsions of nature or cataclysms may have changed the face 
of the earth,— as by throwing down mud and other materials, 
perhaps like the masses of whole continents at a time, — or by 
rending the earth asunder and swallowing up tracts of country, 
not merely like that now forming the great sea- channel 
between the chalk cliffs of England and France, but even 
spaces of world-wide magnitude, as between Europe and 
America, — and thus leaving, like upheaved mountains, some- 
times tilted rock-ridges, as of the nummulitic strata that form 
the basin of the Nile, or the steep and perpendicular cliffs of 
the old red sandstone, now lashed by the angry waves of the 
Atlantic, and the roll of the North Sea waters, at Cape Wrath 
and on the coast of Caithness. 
But if, on the other hand, the mountains of the world be, 
as they are by some scientific men regarded, literally “ up- 
heavals” that have been erupted by the force of subter- 
x-anean or volcanic fires, then the convulsive force required for 
this must be regarded as still infinitely greater; and the 
fearful chasms and terrific cataclysms that would be conse- 
quent upon this tearing of the earth* s crust asunder, when 
heaved into larger space and stretched upwards and outwards, 
we may easily perceive, upon reflection, must be inconceivably 
greater than upon the more probable supposition of an 
occasional falling in of the earth/ s crust and filling up and 
consolidating its interior. The waters alone which spring 
among the hills of ten thousands of rivers that pour their floods 
into the seas, must operate with the mighty force of an in- 
finitely powerful hydraulic engine, which day by day, and ever, 
is pumping and working, and gradually undermining the earth, 
and changing the local intensity of the pressure of that most 
powerful of material agencies, the constant force of terrestrial 
gravitation. 
But if the idea that many of those apparently successive 
generations were possibly contemporaneous and embedded in 
different places about the same time, and that the strata con- 
tainingthem may have afterwards been transported somehow, 
during some ancient convulsion of nature, and laid upon one 
