By degrees, as the waters lost their temperature, and were able to
absorb a copious supply of the carbonic acid gas with which
p 255
the atmosphere was overcharged, they became fitted to hold in solution a
larger quantity of lime.
'The sedimentary strata', setting aside all other exogenous, purely
mechanical deposits of sand or detritus, are as follows:
'Schist', of the lower and upper transition rock, compositing the silurian
and devonian formations; from the lower silurian strata, which were once
termed cambrian, to the upper strata of the old red sandstone or devonian
formation, immediately in contact with the mountain limestone.
'Carboniferous deposits':
'Limestones' imbedded in the transition and carboniferous formations;
zechstein, muschelkalk, Jura formation and chalk, also that portion of the
tertiary formation which is not included in sandstone and conflomerate.
'Travertine', fresh-water limestone, and silicious concretions of hot
springs, formations which have not been produced under the pressure of a
large body of sea water, but almost in immediate contact with the
atmosphere, as in shallow marshes and streams.
'Infusorial deposits': geognostical phenomena, whose great importance in
proving the influence of organic activity in the formation of the solid part
of the earth's crust was first discovered at a recent period by my
highly-gifted friend and fellow-traveler, Ehrenberg.
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