PART II. CHAPTER XVII. 221 



Oolite Group Signs of Land. 



some of the tertiary formations, some species occur both in the 

 older and newer groups, yet these groups may be distinguishable 

 from one another by a comparison of the whole assemblage of 

 fossil shells proper to each. 



Signs of neighbouring land and shoals, The corals and 

 shells above alluded to, and the fish, Crustacea, and other accom- 

 panying fossils, sufficiently attest the marine origin of the oolitic 

 strata in general. Yet there are frequent signs of shallow water 

 and of neighbouring land ; and these are the more worthy of 

 attention, as they by no means diminish as we proceed down- 

 wards to the inferior parts of the oolitic series. Had the bottom 

 of the sea in Europe been unmoved during the entire oolitic 

 period, the first, or oldest beds of the oolite, must have been 

 accumulated in the deepest water, the middle oolite in water of 

 less depth, and the upper in the shallowest of all. The appear- 

 ances about to be described militate against this conclusion. The 

 Kimmeridge clay, in the Upper Oolite, consists, in great part, of 

 a bituminous shale, sometimes forming an impure coal several 

 hundred feet in thickness. In some places in Wiltshire it much 

 resembles peat ; and the bituminous matter may have been, in 

 part at least, derived from the decomposition of vegetables. But 

 as impressions of plants are rare in these shales, which contain 

 ammonites, oysters, and other marine shells, the bitumen may 

 perhaps be of animal origin. The occurrence, however, of fossil 

 wood in the Upper Oolite shows that there were then lands from 

 which plants were drifted into the sea. 



The celebrated lithographic stone of Solenhofen, in Bavaria, 

 belongs to one of the upper divisions of the oolite, and affords a 

 remarkable example of the variety of fossils which may be pre- 

 served under favourable circumstances, and what delicate impres- 

 sions of the tender parts of certain animals and plants may be 

 retained where the sediment is of extreme fineness. Although 

 the number of testacea in this slate is small, and the plants few, 

 and those all marine, Count Munster had determined no less than 

 237 species of fossils when I saw his collection in 1833; and 

 among them no less than seven species of flying lizards, or 

 pterodactyls, six saurians, three tortoises, sixty species of fish, 

 forty-six of Crustacea, and twenty-six of insects. These insects, 

 among which is a libellula, or dragon-fly, must have been blown 

 out to sea, probably from the same land to which the flying 

 lizards, and other contemporaneous reptiles, resorted. 



In one of the upper members of the Inferior Oolite of Eng- 

 land the ripple-mark is distinctly seen throughout a considerable 

 thickness of thin fissile beds of a coarsely oolitic limestone. The 

 rippled slabs are used for roofing, and have been traced over a 



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