MAUVAISES TERRES. 205 
tion by water, the series of events would seem endless, and their magnitude not 
easily to be exaggerated. But it is evident that these superficial mutations are 
trifling in amount, in comparison with revolutions which must have been going on 
simultaneously in the inferior parts of the earth’s crust. The reality of these 
changes is certain, although their nature may be obscure; for we can rarely catch 
a glimpse of the subterranean products of the eocene, miocene, and pliocene epochs, 
because it requires far more time than the tertiary periods have as yet furnished, 
to allow the disturbing causes to uplift, depress, and render open, or for the ocean 
to denude the incumbent rocks, so as to make it possible for an inhabitant of the 
surface to behold them and appreciate their magnitude. 
“The Alps indeed, where the convulsions have been greatest, reveal to us some 
movements of the vast chemical changes and re-arrangement of the component ele- 
ments of rocks which have taken place since the deposition of the eocene tertiary 
strata, and we thus gain some insight into the nature of the transformation of 
mineral masses, which must have been going on cotemporaneously at greater depths. 
“ But although it is only in a few narrow strips of country, like the Central Alps, 
that nature discloses to us some of the nether-formed rocks of such modern geological 
eras, we cannot doubt that still greater modifications of the interior have extended 
down for many miles or leagues in depth beneath the Alps, and beneath every 
region, whether of land or sea, which has risen, sunk, or oscillated in level, since 
the fossil shells and zoophytes of the lower eocene period were living in the sea. 
How much fracture and dislocation of solid rock must have taken place! How 
much heating and cooling, expansion and contraction, drying and baking, softening 
and resolidifying of sedimentary strata! Over how vast an area, and to how great 
a depth, often hundreds of yards or several miles beneath the surface, have mineral 
masses been injected by lava, or dissolved by thermal waters, or corroded by acids, 
or permeated by steam, or impregnated with magnesia, sulphuric acid, or other 
substances introduced in a gaseous form! What obliteration has there not been of 
organic remains, and of the signs of stratification, in the course of the tertiary ages 
which have elapsed since the nummulitic strata and incumbent fucoid grits lay 
submerged beneath the ocean !” 
I have spoken of the eocene tertiary as modern compared with the palzozoic 
division below the coal-measures ; this is only geologically and comparatively speak- 
ing; estimated in time—by a human epoch—the date of the eocene tertiary is 
immeasurably great—utterly beyond the grasp of our conceptions to appreciate, 
counted by single years, comprising, as it does, a cycle of geological events that has 
completely changed the whole physical geography of the world—turned continents 
into oceans, and oceans into dry land; and this, not by one grand bouleversement of 
the earth’s crust, but by a long series of gradual changes, which, except at certain 
periods, of paroxysmal throes, occasionally occurring at long and distant intervals, 
was probably as slow and gradual as the present rising of the coast of Sweden out 
of the ocean, and the simultaneous subsidence of land over the bottom of the Poly- 
nesian Archipelago. 
Turning to the figures engraved from daguerreotypes representing the anatomical 
