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Show 52 SUBDIVISIONS OF [Ch. V. d th dd.tl'ons to the recent species in the cabinets access, an e a 1 of cone1 1 01 o gt·s t s m· London ' have been so great of. late years, that m· many ex t en sive genera the number of spectes has been 1 d bled But as the greater part of these newly~ more t 1an ou · . . discovered shells have been brought from the Pacific and other distant seas, it is probable that these accessions would not materially alter the results given in the tables, and it must, at all events, be remembered, that the only effect of such additional information would be, to increase the number of identifications of recent with fossil species, while the proportional number of analogues in the different periods might probably remain nearly the same, SUBDIVISIONS OF :THE TERTIARY EPOCli. Recent formations.-"\V e shall now proceed to consider the subdivisions of tertiary strata which may be founded on the results of a comparison of their respective fossils, and to give names to the periods to which they each b_elong. The tertiary epoch has been divided into three periods in the tables; we shall, however, endeavour to establish four, all distinct from the actual period, or that which has elapsed since the earth has been tenanted by man. To the events of this latter era, which we shall term the recent, we have exclusively confined ourselves in the two preceding volumes. All sedimentary deposits, all volcanic rocks, in a word, every geological monument, whether l;>elonging to the animate or inanimate world, which appertains to this epoch, may be termed recent. Some recent species, therefore, are found fossil in various tertiary periods, and, on the <;>ther hand, others, like the Dodo, may be e:vtinct, for it is sufficient that they should once have coexisted with man, to make them referrible to this era. Some authors apply the term contemporaneous to all the formations which have originated during the human epoch; but as the word is so frequently in use to express the synchronous origin of distinct formations, it would be a source of great inconvenience and ambiguity, if we were to attach to it a tech .. nical sense. Ch. V.] THE TERTIARY EPOCII. 53 We may sometimes prove, that certain strata belong to the recent period by aid of historical evidence, as parts of the delta of the Po, Rhone, and Nile, for example; at other times, by discovering i~bedded remains of man or his works; but when we have no evidence of this kind, and we hesitate whether to ascribe a particular deposit to the recent era, or that immediately preceding, we must generally incline to refer it to the latter, for it will appear in the sequel, that the changes of the historical era are quite insignificant when contrasted with those even of the newest tertiary period. Newer Pliocene period.-This most modern of the four subdivisions of the whole tertiary epoch, we propose to call the Newer Pliopene, which, together with the Older Pliocene, constitute one group in the annexed tables of M. Deshayes. We derive the term Pliocene from wi-..et~v, major, and xa1vor, recens, as the major part of the fossil testacea of this epoch are referrible to recent species*. Whether in all cases there may hereafter prove to be an absolute preponderance of recent species, in every group of strata assigned to this period in the tables, is very doubtful; but the proportion of living species, where least considerable, usually approaches to one-half of the total num her, and appears always to exceed a third; and as our acquaintance with the testacea of the Mediterranean, and some other seas, increases, it is probable that a greater proportion will be identified. * In the terms Pliocene, Miocene, and Eocene, the Greek diphthongs ei and ai are changed into the vowels i and e, in conformity 'with the idiom of our language. Thus we have Encenia, au inaugural ce1·emony, derived from n and JealvDs, recPns; and as examples of the conversion of ei into i, we have icosahedron. I have been much indebted to my friend, the Rev. W. Whewell, for assisting me in inventing and anglicizing these terms, and I sincerely wish that the numerous foreign diphthongs, barbarous terminations, and Latin plurals, which have been so plentifully inhoduced of late years into our scientific language, had been avoided as successfully as they are by French Naturalists, and as they were by the earlier English writers, when our language was more flexible than it is now. But while I commend the French for accommodating foreign terms to the structure of their own language, I must confess that no naturalists have been more unscholarlike in their mode of fabricating G1·eek derivatives and compounds, many of the latter being a bastard offspring of Greek and Latin. |