The Wonders of Geology, or a Familiar Exposition of Geological Phenomena

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1858 edition. Excerpt: ...with carbonic-acid gas as to be unfitted for the respiration of animals of a higher order than reptiles; and that the dense and luxuriant vegetation of that epoch was designed to pnrify the air, by elaborating coal, and thus abstracting the superabundance of irrespirable gas, and setting free a corresponding proportion of oxygen: thus rendering the surface of the earth suitable for the existence of terrestrial reptiles, and ultimately of birds and mammalia. But Sir C. Lyell has argued that, so far as we know, if any change were induced in the constitution of the atmosphere by such an agency, it would be the reverse of that assumed; for an excess of vegetation would tend to diminish the average amount of carbonic acid, and consequently the air must have been purer than in the succeeding epochs, t It is therefore probable that the absence of herbivorous animals cannot be explained by unfavourable atmospheric conditions: and again we may point to New Zealand as a country having a luxuriant vegetation, yet without herbivorous quadrupeds. 42. Formation' or Coal-measures.--From the facts which have passed under our examination, we may now advantageously consider what were the circumstances which gave rise to these prodigious layers of carbonized matter The Plagiaulax of Purbeck and the Stereognathtu of StonesfiVId were smaller herbivores. The other known mammals of the secondary period were probably insectivorous. t Lyell's Travels in North America, ' vol. i. p. 152; and Principles, p. 248. t The only indigenous mammals in New Zealand are one species of Rat and another of Bat; and there are no large reptiles whatever ', See especially p. 691, Ac. unmixed with other materials, --these immense beds of vegetables, from which animal remains...