284 Dr. Mac Culloch on the 
the latter: we can only infer from observation and analogy, that 
the immense masses of our present calcareous strata have been 
thus produced. We transfer from the bottom of the sea those 
operations which we know to be daily going on; and, reasoning 
on them, recur to a time when our limestones. were in the same 
act of being formed, and were preparing for future dry land; 
Jand to be laid dry by its own elevation, or by the receding of 
the waters, as geologists shall hereafter agree or prove. But 
there is a perfect and complete chasm between the two, at least 
in the case of marine strata, In the terrestrial or fresh water 
ones’ it is otherwise; as we can follow the marly deposit of a 
lake till it rises to the level of the water, and, gradually ex- 
cluding it, prepares the dry land; an operation of which every 
country, and our own mountainous region as distinctly as any, 
‘affords daily proofs in the marl deposits, covered with soil and 
-peat, that are found throughout the Highlands of Scotland. 
In the coral formation, this chasm, even as to the marine 
strata, is filled up. Such is the nature of the animals in this case, 
that instead of spreading their manufactures, if I] may use such a 
word, along the bottom of the ocean, as the shell-fish do, and 
concealing. their stupendous works far beneath the regions 
accessible to man, their tendency is to seek the surface of 
the sea. There the huge strata which they produce are brought 
to light, even during their own and our existence, and we be- 
come acquainted with rocks that may be considered as fossil 
and living at the same time. When once the animals have 
deserted their habitations, when these have reached, as they.do, 
above the surface of the water, and even far up into dry land, 
into islands of great extent, they must be considered fossil 
productions, as much as any other calcareous strata. 
It appears that each coral, whatever its species be,is a solid 
calcareous structure, somewhat resembling a vegetable in the 
general progress and increase of its parts, inhabited by nume- 
rous similar animals, which are precisely the same for each 
individual coral, but different in the different species. Each of 
these corals may thus be considered as a colony, the inha- 
bitants being disposed in minute cells, where they reside 
