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. 1884 Excerpt: ...different species. All the animals and plants inhabiting the earth at one time are called the fauna and flora of that geological time. Thus we have a fauna and flora of Tertiary times, of Jurassic times, of Devonian times, etc. Definition of Formation and Period.--When the strata are conformable, the change from one ...
Read More
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. 1884 Excerpt: ...different species. All the animals and plants inhabiting the earth at one time are called the fauna and flora of that geological time. Thus we have a fauna and flora of Tertiary times, of Jurassic times, of Devonian times, etc. Definition of Formation and Period.--When the strata are conformable, the change from one geological fauna to another is gradual, but a line of unconformity usually abruptly separates two faunas. A formation, therefore, is a series of conformable strata, in which the fossil species are either the same or change very gradually; and a geological period is the period during which such a formation has been laid down. There are two tests, therefore, of the limits of a geological formation and a geological period, viz., unconformity of the rock-system and great change in the species. Of these the latter is most valuable. Law of Gradual Approach to the Present.--It is a fundamental and very important fact that in the successive changes of geological species there is a steady approach to living forms, first in families, then in genera, and then in species. Species do not begin to be identical with the living species until the Tertiary period, and thence onward we have an increasing percentage, identical with the living. Now, we determine that rocks belong to the same time, all over the earth, by the general similarity of the fossil species. We find difficulty in applying this rule only in the Tertiary, because then the geographical diversity is beginning to be so great as to seriously interfere with the general similarity. But just here we begin to use another principle, viz., the percentage of the fossil species still living in the immediate vicinity. Similar percentage indicates the same age--greater percentage less age, and less percentag...
Read Less
Choose your shipping method in Checkout. Costs may vary based on destination.
Seller's Description:
PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
Choose your shipping method in Checkout. Costs may vary based on destination.
Seller's Description:
PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
Choose your shipping method in Checkout. Costs may vary based on destination.
Seller's Description:
PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
Choose your shipping method in Checkout. Costs may vary based on destination.
Seller's Description:
PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
Choose your shipping method in Checkout. Costs may vary based on destination.
Seller's Description:
PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
Choose your shipping method in Checkout. Costs may vary based on destination.
Seller's Description:
PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
