Page:A Treatise on Geology, volume 2.djvu/53

 CHAP. VI. completion of the present arrangement of organic life, and main features of physical geography in these regions; viz. the eocene or lower tertiary mammalia and the animals of the diluvial period. Between these two groups, are many assemblages of intermediate character, and intermediate geological position (as in Touraine), and later than all of them are other deposits which (imperfectly) unite the diluvial to the existing fauna. The mammalia whose remains lie in the lower tertiary rocks may be considered as having lived on the land previously to the origin of these strata; and those whose relics fill caverns and gravel-beds obviously belong to a surface of the earth which has been modified by subsequent revolutions. We have therefore the following general classification of the results arrived at in studying fossil mammalia:—

Mr. Lyell's classification of tertiary strata (vol. i. p. 267.) may be easily reduced to this scale, with sufficient accuracy for our present purpose, by reading for diluvial, newer pleiocene (according to the tendency of book iv.