of the earth's surface),--it would seem that the whole subject of these newer calcareous formations requires elucidation: and, if the inferences connected with them do not throw con- sider?ble doubt upon some opinions at present generally received, they show, at least, that a great deal more is to be learned respecting the operations and products of the most recent geological epochs, than is commonly supposed. Since it appears that the accretion of calcareous matter is continually going on at the present time, and has proba- bly taken place at all times, the stone thus formed, inde- pendent of the organized bodies which it envelopes, will afford no criterion of its date,--nor give any very certain clue to the revolutions which have subsequently acted upon it But as mar/he shells are found in the cemented masses, st heights above the sea, to which no ordinary natural ope- rations could have conveyed them, the elevation of these shells to their actual place, (if not that of the rock is which they are agglutinated,) must be referred to some other agency :--while the perfect preservatio? of the shells, their great quantity, and the abundance of the same ape- cies in the same places, make it more probable that they lay originally in the situations where we now find them,' than that they have been transported from any cortaidcable distances, or elevated by any very turbulent operation. Cap- tain de Freycinet, indeed, mentions that pate!Ira, worn by at- trition, and other recent Shells, have been found on the west coast of New Holland, on the top of a wall of-rocks an hundred feet above the sea,---evidontly brought up by the surge during violent storms *; but such shells are found in �Freyeinet, p. 187.--The presence of shells in tach situations may often be ascribed to the birds, whleh feed on their inhabitants. At Madeira, where recent shelb are found near the coast at a con-
�
