120 Scientific Intelugence. 
ses after cutting through the St. Louis limestone, this seam of one to two 
feet thickness; it then enters the sandstone, w ich here is not as thick as 
at Prairie du Rocher, and at last exposes the lower carboniferous lime- 
ably near a thousand feet thick, at least where the Mississippi cuts through 
it from twenty to sixty miles vis. This lower carboniferous 
limestone se color, often bituminous, and mostly erystal- 
oO! 
banks of the peti yer white oolite near St. Geneviéve, which is worked 
there and is frequently sent down the river, are in the lower part of this 
. Only the lower carboniferous ‘limestone contains the beauti- 
Owen is therefore the lower part of the carboniferous limestone of east- 
ern meee and southern Illinois, and our St. Louis limestone is its up- 
per par 
Dr. HK ing, who has seen this formation in the southwestern parts of 
Missouri, thinks that on the Osage river, this lower limestone formation 
] strat it] 
times not far above and — from the lead-bearing .magnesian strata, 
are in this same lowest coal bed. 
7. Cause of a <n of Ancient Marine Formations from certain 
by Cuartes Darwin, (Geological Observations on South 
America, p. 136. Can any light be thrown on this remarkable absence 
of recent P achiler rous deposits on these coasts, on which, at an ancient 
tertiary aie strata abounding with organic remains were extensively 
accumulated? I think there can, namely, by considering the conditions 
necessary ir the preservation of a formation to a distan t age. ing 
bd the enormous amount of denudation which on all sides of us has been 
cted, #8 evidenced by the lofty cliffs cutting off, on so many coasts, 
fi 
horicoritl once far extended strata of no great antiquity (as in the 
case of Patagonia),—as evinced by the level Paitthes of the ground on 
bid sides of ae faults and dislocations, by inland lines of escarp- 
s, by outliers, and numberless other facts, and by that argument of 
high ‘generality aaeanoad by Mr. Lyell, namely, that every sedimentary 
formation, whatever its thickness may be, and over however many hundred 
square miles it t may extend, is the result and the measure of an equal 
facts, we must conclude that, as an ordinary rule, a formation bi resist 
such vast destroying powers, and to last to a distant epoch, must be of 
wide extent, and either in itself, or together with esivcnbett pokes 
be of great thickness: Tn this discussion, we are considering only forma- | 
tions containing the remains of marine animals, which, as before men- 
tioned, live, with some exceptions, within (most of them much within) 
depths of a ae fathoms. How, then, can a thick and widely ex- 
tended formation be iecumoulated, which shall include such organic re+ 
mains? First, let us take the case of the bed of the sea long remaining 
at a stationary level: under these circumstances, it is evident that conchif- 
erous strata can accumulate only to the same thickness with the depth at 
* 
