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Show 144 NEWER PLIOCENE PERIOD. [Ch. XI. Kaola, and Phalangista, have been recognized. :he gre~ter part of them belong to existing, but several to extmct, spectes. One of the bones is of much greater size than the rest, and is d by Mr Clift to belong to an hippopotamus *. suppose , . ' . In a collection of these bones sent to Paris, Mr. Pentland thought he could recognize a species of Halmaturus of larger size than the largest living kangaroo T · These facts are full of interest, for they prove that the peculiar type of organiz~tion which now char~cter~zes the marsupial tribes has prevailed from a remote penod m Aus· tralia and that in that continent, as in Europe, North and South Ame:ica, and India, many species of mammalia have become extinct. It also appears, although the evidence is less complete than we could have wished_, that land quadrupeds, far exceeding in magnitude the wild species now inhabiting New Holland, have, at some former period, existed in that country. Breccias now forming in the Morea.-Respecting the various ways in which fissures and caverns may become gradually filled up with osseous breccias, we may refer the reader to what we have said in a former volume+· It appears, however, from a recent communication of M. Boblaye, that the Morea is, of all the countries hitherto investigated, that which throws the great· est light on the mode in which the Mediterranean breccias may have originated. In that peninsula a great many of the rivers and torrents terminate in land-locked hollows, where they are engulphed in chasms which traverse limestone. They sometimes reappear at great di~tances .. but generally they discharge their waters below the level of the sea. ' Numerous bone caverns,' says M. Boblaye, ' may thus be filling up in our own times, and the gulphs (katavothrons) of the plain of Tripo1itza have swallowed up of late years thousands of human bones, mingled * Mr. Clift, Ed. New Phil. Jouru,, No. xx. p. 394,-Major Mitchell, Proceed· ings ofGt.>ol. Soc., 1831, p. 321. . t Journ. de Geologie, tome iii. p. 291. The bone of an elephant menhoned by Mr. Pentland was the same large bone alluded to by Mr. Clift, t Vol. ii. chap. xiii. Ch. XI.] NEWER PLIOCENE ALlUVIUMS, 145 with the same ochreous clay which envelops the osseous remains of higher antiquity *.' NEWER PLIOCENE ALLUVIUMS. Some writers have attempted to introduce into their classification of geological periods an alluvial epoch, as if the transportation of loose matter from one part of the surface of the land to another had been the work of one particular period. In our opinion, they might have endeavoured, with equal propriety, to institute a volcanic period, or a period of marine or fresh·water deposits. We believe_, on the contrary, that alluvial formations have originated in every age, but more particularly during those periods when land has been raised above its former level, or depressed below it. We defined alluvium to be such transported matter as has been thrown down, either by rivers, floods, or other causes_, upon land liable to inundations, or which is not permanently submerged beneath the waters of lakes or seas t. As examples of the other causes adverted to in the above definition_, we might instance a wave of the sea raised by an earthquake, or a water-spout, or a glacier. We have said permanently submerged in order to distinguish between alluviums and regular subaqueous deposits. The latter are accumulated in lakes or great submarine receptacles, the former in the channels of rivers and currents, where the materials may be regarded as being still in t-ransit'U_, or on their way to a place of rest. There may be cases where it is impossible to draw a line of demarcation between these two classes of formations, but these exceptions are rare, and the division is, upon the whole, convenient and natural the ci:c~mstunces being very different under which each ~roup ongmates. Marine alluvium.-The term 'marine alluvium' is perhaps admissible if confined to banks of shingle thrown u~ like th~ * Journ. de Geologie, tome iii. No. x. p. 1G5. t Vol. ii. chap. xiv. Voi .. III. L |