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XXVIII. Observations on the Formation of the Chalk Strata and on the Structure of the Belemnite

Published online by Cambridge University Press:  17 January 2013

Extract

Of the various rocks of which the Earth's surface is composed, there are some which present very satisfactory indications of their origin; while others, when considered in that respect, seem to be placed almost beyond the reach of hypothesis. The Granite and Trap rocks, by extending their ramifications among their contiguous neighbours, distinctly avow, not only a subsequent formation, but, in many instances, they present the most unequivocal marks of an igneous origin. The Limestones and Sandstones, however, are equally constant in their indications of aquatic deposition, although, at the same time, the assistance of another agency may sometimes be inferred, when their consolidation and position are taken into the question. Of all the rocks with which I am acquainted, there is none whose formation seems to tax the ingenuity of theorists so severely, as the White Limestone or Chalk, in whatever respect we may think fit to consider it.

Type
Research Article
Copyright
Copyright © Royal Society of Edinburgh 1823

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References

page 413 note * In specimens of this kind, I have noticed that the connection between these globular masses, is maintained, more particularly by two fibres, larger than the others, and more uniform in their position.

page 415 note * Naturalists, having any connection with Ireland, will have no difficulty in supplying themselves with specimens; for although Mr Parkinson mentions the belemnite being found transfixed in flint as a circumstance of some rarity, the north of Ireland affords an unbounded resource; and it will be very interesting to me to learn, that this fossil, found under similar circumstances in other places, presents the same phenomena.

page 418 note * I learnt from Mr Hodgkin, that they had recently been found in situ in the vicinity of Lewis.