94 



CARBONIFEROUS LIMESTONES OF I 0 W A. 



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 1 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 II. 



THEIR PALAEONTOLOGY. 



The 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 fringed 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. 



