44.4, A POPULAR EXPOSITION OF THE 
maintains that certain inclined strata of mechanical formation were ori- 
ginally of inclined deposition. This may be true under local or excep- 
tional, but certainly not under general, conditions. (See proofs, further 
on.) Where, however, sands and gravels are thrown down by currents 
and running streams, an oblique arrangement commonly takes place ; 
but this is more or less confined to the subordinate layers of which the 
larger beds consist, as shewn in the annexed figure. The inclined 
layers have sometimes different degrees of inclina- 54, 
tion, and even dip (in different beds of the same 
strata) in opposite directions, indicating changes in 
the tidal or other currents by which they were 
thrown down. This inclined arrangement is termed ZFYyyyyy 
‘false bedding,” or “oblique stratification.” It Lddttdldtcldll 
may be seen in some of the more ancient, and also in some of the 
more modern deposits of this continent, as in the Potsdam Sandstone 
of the south shore of Lake Superior, and in the Drift gravels of many 
parts of Canada. 
Having thus rapidly traced out the formation of the mechanically- 
formed sedimentary rocks up to their deposition in the state of detrital 
matter on the beds of seas, lakes, or estuaries, we have now to inquire 
how these accumulations of mud, sand, &c., become hardened into 
rock, properly so-called. 
Consolidation of Sediments.—Most sediments hold within them- 
selves the elements of their own consolidation, in the form of particles 
of calcareous or ferruginous matter, which act upon the other sub- 
stances in the manner of a cement. Frequently, also, a large amount 
of calcareous matter is derived from the decomposition or solution of 
imbedded shells and other organic remains made up of carbonate of 
lime. In the majority of strata, and in sandstones more especially, 
merely cast: or shell-impressions are thus left, in place of the origin- 
ally imbedded shells. Masses of solid conglomerate are daily under 
process of formation, in places where springs containing calcareous 
or ferruginous matter infiltrate through the gravels and pebble-beds 
of our Drift deposits. Many thermal springs (and even ordinary 
river-water) also=contain considerable quantities of silica in solution ; 
and there is reason to believe that in former periods of the Earth’s 
history, springs of this kind must have prevailed to a very great ex- 
tent. These'flowing into seas and lakes where sediments were under 
process of deposition, must also have lent their agency towards the 
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