FACTS AND INFERENCES. 293 



the series, the ironstone forms a crust over it, as if it had subsided to 

 the bottom. Any hard seam, either in the chalk, the shale, or other 

 principal beds, would suffice to cut off the communication with the 

 beds below ; and this accounts for our finding the secretions stopping 

 at different stages, instead of descending wholly to the bottom. Even 

 where the seams of nodules form nearly continuous beds, as is the 

 case with the flint, the ironstone, and the lias seams, they may still 

 have been secretions from the beds in which they run. The notion 

 which some authors have adopted, that these substances, particularly 

 flint, may have been forcibly injected from below into the principal 

 beds, like melted lead, is utterly irreconcilable with the phenomena 

 presented. Where are the openings through which the fused sub- 

 stance was forced ? Why has none of it stuck in the strata which it 

 pierced ? Or how could it assume, in the case supposed, the form which 

 it now wears ! We may, indeed, feel a difficulty in conceiving, how 

 such secretions could take place ; but it is as difficult to conceive, 

 how the consolidation of the strata was produced. If chemical 

 agents effected the one, might they not also accomplish the other ? — 

 This leads us to remark, 



12. The members of the strata are in very different states of indu- 

 jation, and as the difference is not according to the order of succes- 

 sion, it must be owing to a difference in their intrinsic qualities, and 

 in the circumstances of their deposition, rather than to any extraneous 

 cause.' — We have seen, that some of the strata are remarkably soft, 

 while others are extremely hard. Some of the calcareous beds consist 

 of loose marl, others are highly crystalline, approaching to marble ; 

 some of the sandstones are very friable, and nearly in the state of 

 sand, while the crow-stone beds are hard and compact, like quartz 

 rock ; and some of the shales are soft, like clay, others are hard and 

 splintery. We have observed a similar difference in our organic re- 

 mains, some being merely preserved, others in various states of 



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