94 CARBONIFEROUS LIMESTONES OF IOWA. 
Between the Yorkshire and American groups a further analogy is observable in 
the dolomitic beds. Phillips remarks :* ! 
“The limestone in the country about Kettlewell is often liable to a local change 
into a crystallized yellowish or brown dolomitic rock, full of ramifications, and 
nodules, and hollow cells of calcareous spar. The beds and joints in this ‘dun 
lime, for so it is called by the workmen, are very irregular, and the rock feels 
heavy. Altogether, it resembles not a little the brown dolomitic rock of Gerol- 
stein, in the Eifel. It is known to the miners that this ‘dun lime’ runs in lines 
north and south, destroying the productiveness of the veins through the whole 
mass of limestone.” 
The sections at the upper end of Wensley Dale indicate also a marked simi- 
larity in the succession of limestones and grits under the coal of Lunsthorn, 
to that which occurs under the lowest coal-bed on the Des Moines; though it 
does not appear that the Wensley Dale limestones have the peculiar nodular and 
concretionary character which characterize those of Kettlewell and of Iowa. The 
grits, too, attain a greater thickness than in Iowa, and there is more shaly matter 
interposed between the limestones and grits, so as to augment the transatlantic 
beds to nearly four times the thickness of those in Iowa. 
SECTION IT. 
THEIR PALAONTOLOGY. 
Tue study of organic remains in rocks is, indeed, a most beautiful, a most 
fascinating research. What can be more extraordinary: that we, the generation of 
the nineteenth century, should exhume from out the hard substance of the solid 
rocks the delicate forms of organic beings of bygone ages, and display to the won- 
dering eye of the naturalist, even their minute, anatomical details! And this, not 
alone of races which inhabited this earth in times immediately preceding the human 
epoch; we are even permitted to contemplate, and restore to our perceptions, the 
very fishes, mollusks, and corals, that swarmed in the carboniferous seas millions of 
ages ago. The animal matter composing their tissues and bones is indeed gone, 
but the simultaneous mineral infiltrations preserve a perfect counterpart. We can 
depict those remarkable and elegant forms of vegetation which constituted the 
forests that frmged the shores of that same treacherous and ever-overwhelming 
ocean. We seize them in the very act of uncoiling their fronds, and unfold to the 
admiring gaze of the botanist, that luxuriant canopy of foliage that once waved in 
the sea-breeze nurturing their stems. We accomplish even more than this: we can 
read the records of myriads of the lower orders of animals, that date their existence 
yet further back than the times that gave growth to trees, now stored up as mineral 
fuel in the bowels of the earth—to times at least as long prior to the coal formation 
as that geological era is antecedent to the present time; we can assign to each its 
* Geology of Yorkshire, p. 26. 
