period, the dry land in the northern hemisphere has been continually on the increase, not only because it is now greatly in excess beyond the average proportion which land generally bears to water on the globe, but because the comparison of the secondary and tertiary strata implies a passage throughout the space now occupied by Europe, from the condition of an ocean interspersed with islands to that of a large continent. But if it were possible to represent all the vicissitudes in the distribution of land and sea that have occurred during the tertiary period, and to exhibit not only the actual existence of land where there was once sea, but also the extent of surface now submerged, which may once have been land, the map would still fail to express all the important revolutions in physical geography, which have taken place within the epoch under consideration. The oscillations of level have not merely been such as to lift up the land from below the waters to a small height above them, but in some cases a rise of several thousand feet has been effected. Thus the Alps have acquired an additional altitude of from 2000 to 4000 feet, and even in some places still more; and the Apennines owe a great part of their height (from 1000 to 2000 feet and upwards) to subterranean convulsions which have happened within the tertiary epoch. On the other hand, some mountain chains may have been lowered, during the same series of ages, in an equal degree, and shoals may have been converted into deep abysses. It would be superfluous to point out in detail the bearing of the facts exhibited in this map, on the theories proposed in a former part of this volume, respecting the migrations of animals and plants, and the extinction of species; and it would be equally unnecessary to enlarge on the variations in local climate, which must have accompanied such vicissitudes in physical geography. But the general temperature, also, of the habitable surface of the globe, as well as the local climates, may have been considerably modified by such extraordinary revolutions. The alteration in climate, implied by a comparison of the organic remains of the older tertiary strata, and the species of living animals and plants, does not appear to be so great as would be produced if the temperature of our tropics were now transferred to the temperate zone, and the temperature of the latter to the arctic. We do not, therefore, anticipate that the reader, who has duly studied the arguments explained by us in the 6th, 7th, and 8th chapters of the first volume, will object to the adequacy of the cause proposed, on the score of the small quantity of geographical change during the time in question. But if there be good reason to conclude that the change would be fully adequate, in point of the magnitude of its effects, this cause, we conceive, ought to supersede every other of a purely speculative nature, until some argument can be adduced to prove that the change has not acted in the right direction *. Some persons, but slightly acquainted with the present state of geology, have objected, that the lands in high northern latitudes have not been recently elevated. If they had reflected that every year we are making some new discoveries respecting the periods when tracts in the immediate neighbourhood of the great European capitals emerged from the deep, and had they sufficiently considered that the antiquity of a group of rocks has no necessary connexion with the date of its elevation, they would probably have seen the futility of such arguments. As far as we can conjecture, from the very scanty information which we possess of the geology of the arctic region, there is no want of proofs of comparatively recent alterations of level. In conclusion, we may remark that the portion of Europe distinguished in this map by colours and ruled lines, comprises the greater part of the globe now known to geologists— almost all at least that is known in such a manner as to entitle any one to speculate on the mutations in physical geography which have taken place during the tertiary period. * See Mr. Herschell's remarks on a change of climate.-Disc. on the Study of Nat. Phil., pp. 146 and 148. In regard to other parts of the world, we have no reason for inferring, from any data hitherto obtained, that during an equal lapse of the ages which immediately preceded our times, an equal amount of alteration of surface may not have taken place. LIST OF WOOD-CUTS. 1. Eggs of fresh-water Molluscs, p. 111. 3. Stem and branches of ditto, p. 274. 4. Chain of coral islets, called the Maldivas, p. 286. 5. View of Whitsunday Island, p. 289. 6. Section of a coral island, p. 290. 7. Ditto of part of a coral island, p. 290. INDEX. VOL. II. ACQUIRED habits of animals rarely, Ælian, on the breeding of elephants in Africa, devastations caused by locusts many species probably annihilated dried carcasses of camels imbedded strata now forming off the coast African desert, its area as compared to the Mediterranean, 166. may leave traces of their form in Alloa, whale cast ashore at, 278. fossil whale found near, 279. Alluvium, stalagmite found alternating imbedding of organic remains Alps, have been greatly raised during the tertiary epoch, 308. Alternations of marine and fresh-water America, specific distinctness of the ani- domesticated animals have run rapid multiplication of domestic number of plants common to the number of square miles of useful undergone great effects which it is said would re- Animal remains in caves and fissures 219. Animals, Lamarck's theory of the pro- imported into America have run aptitude of some kinds to domes- hereditary instincts of, 39. some of their qualities given with their acquired habits rarely trans- changes in the brain of the fœtus their agency in diffusing plants, 78. their powers of swimming, 92. their power of crossing the sea causes which determine the sta- influence of society in altering the migratory powers indispensable manner in which they become remains of those most common in most abundantly preserved where 247. imbedded by floods in Scotland, 230. found imbedded in Scotch marl Animate creation, changes now in pro- Antagonist powers, synchronism of their Antiseptic property of peat, whence de- Ants, their ravages in Grenada, 137. Apennines, have been a vegetable centre their rapid multiplication, 135. Apure, river, wild horses drowned in Aquatic and terrestrial species, their re- Aquatic species, imbedding of their re- Arabian Gulf, rapidly filling with coral, Arctic region, on alterations of level in Ass, the, has run wild in Quito, 153. wild, account of their migrations Athabasca Lake, large shoal formed by Atlantic, absence of circular coral groups Aubenas, fissures filled with breccia Barriers to the distribution of species, Barrow, Mr., his account of a bank Barton, Mr., on the agency of insects in on the geography of plants, 67. black, migrate in great numbers, 94. remains of the, found in shell- Bee, number of instincts of the, 58. 234. on the buried temple of Ipsambul, on the rate of the growth of coral on the situation of the channels on the superior height of the on recent changes of level in the Belcher, Captain, on the strata now Augustin, St., on a plague caused by Belzoni, on the buried temple of Ipsam- locusts in Africa, 137. Australia, the kangaroo and emu giv- vegetation of, 178. extent of coral reefs off the coast Baboon of Sumatra, trained to ascend Bacon, Lord, on the vicissitudes of Baffin's Bay, marine animals found at his account of the fall of Mount Bakie loch, charæ found in a fossil state Ballard, M., on changes which some bul, 234. - his account of a flood on the Nile, Berkely, on the recent origin of man, Bewick, on the great geographical range on the distribution of the bustard Bhooi, volcanic eruption at, during Bigsby, Dr., on the North American Birds, diffusion of plants by, 80. geographical distribution of, 100. their agency in the distribution of many species of, unremittingly |