But other theories have also been entertained on this head, particularly by the elder De Luc; and as we are by no means desirous that our readers should be guided by any set of opinions, merely because they may seem to us the best, we shall here give a view of the joint opinions of himself and his nephew on this subject.
The theory Cr the first of these philosophers is, that the ancient ocean must have been covered with islands, and intersected by numerous peninsulas in a state of con stant revolution; in consequence of which they were sometimes separated, and at others reunited, either with each other, or with the neighbouring continents. In the same way he imagines, they must have been alternately laid dry and inundated. When in the former state, they were inhabited by animals; while, in consequence of the latter revolutions, the inhabitants were destroyed and buried in the last deposits that were left by the sea. In this way is explained that condition of the fossil remains of Italy, of which we have attempted to give a different solution. Thus also he accounts for the occasional inter mixture of terrestrial and marine remains. 'Where such alluvia continue flat or regular, no other revolutions have interfered with them; but wherever the reverse is the case, he considers that they have been subject to the same changes that have determined the forms of the continents ; and that, whatever revolutions of nature the solid rocks have undergone, whether in the form of fractures, or dislocations, or subsidence, the same have been shared by the alluvial deposits. Thus a number of successive revolutions took place in ancient times, until one grand catastrophe of the same nature finally determined the sea to abandon these lands, and to leave them in the state in which we now find them. The last, or most superficial strata of all, are those which the sea last abandoned. It is not here our object to criticise this theory, which, it is easily seen, leads to consequences at variance with every theory of the earth and with a great number of its appear ances; and which could not be reconciled even to Cuvier's views of this subject, although he follows De Luc in most of his opinions.
To support this view, Mr. A. J. De Luc gives a state ment of the alluvia and bones of northern Asia, which we here abridge. The banks of the Irtish, between the 55th and 56th degrees of latitude, are high, and out of them the river occasionally washes the bones and teeth of elephants. To the north of Berezoff, in 65°, the Oby is skirted by hills, which form for it high banks, consisting of clay and sand. The lower parts of these banks are
also full of organic remains of the same nature, which are occasionally disclosed by the undermining operations of the river. An unnamed island in the Icy Sea is also de scribed as consisting of banks of sand and ice intermixed, in which numerous remains of fossil elephants arc found whenever a thaw causes them to break down. In the sand of the Irtish these bones are often mixed with shells; and not far from the Iset river, which runs into the Tobol, the same intermixture has been discovered, namely, the hones of elephants and of sharks; the whole being covered by eight beds of alternating sand and clay. These upper beds, Dl. De Luc, apparently without justifiable cause, considers as a marine deposit.
Besides these places, elephants' bones intermixed with shells, (marine?) or at least occupying the same beds, have been found in many other parts of this country, such as near the Jaik, the Kama, and the Toura ; those of Italy, which he also names along with them, we omit, as utterly distinct cases. This confusion of two • distinct deposits, originating in different causes, is important ; because from the adhesion of oysters to the bones of whales in Italy, our author here argues generally with respect to the whole of these fossil remains, in whatever situation.
Hence the same conclusions are derived respecting the existence of islands and successive revolutions, as by the older philosopher of this name ; at least in all those cases where the bones are dispersed, or injured, or intermixed, and imbedded in sand and maple But he explains another state of these, not uncommon, which does require explanation, by a suggestion similar to that which we have adopted respecting the elks of the Isle of Man. Here, like ourselves in similar cases, he differs from Cuvier, who imagines that all these hones had been deposited in the places where they are found, before they were covered by the sea. He supposes that circumstan ces had forced these animals into one spot in such cases; a marine inundation, we must presume, from his peculiar views; and that, having there died of hunger, they were afterwards buried in the alluvia which the sea continued to bring upon them. In other cases, the inundations or irruptions of the sea increasing or continuing, the bones became dispersed, or carried to lower situations. After this, the sea is supposed to have remained in a state of tranquillity for a considerable time, so as to accumulate marine animals, and then, fresh revolutions taking place, more confusion was the consequence.