In this case, as in the other, let us grant, for the argument's sake, all the facts. Let us admit that the trench through which the St. Lawrence now flows has been cut by the river in somewhat less than six thousand years. But through what, let us ask, has it been cut? There can exist no doubt on the subject: it has been cut through an ancient graveyard of the Upper Silurian system, charged with the peculiar fossils characteristic of what are known as the Clinton and Niagara groups, and common, many of them, to the Upper Silurian of our own country and of the European continent. _Leptæna depressa_ and _Pentamerus oblongus_, two of the most frequent shells of the deposit, occur also in equal abundance in the Dudley and Caradoc formations of England; its prevailing encrinite, _Ichthyocrinus lævis_, is scarce distinguishable from an encrinite which I have often picked up in the quarries of the "Wren's Nest" (_Ichthyocrinus pyriformis_); while its prevailing trilobite, _Phacops limulurus_, seems to be but a transatlantic variety of our well known _Asaphus (Phacops) caudatus_. Further, the sequence of the various formations both above and below the Niagara group, is shown with remarkable distinctness in that part of the world along the shores of the great lakes. They may be traced downward, on the one hand, along the Lower Silurian deposits, to the non-fossiliferous base on which the system rests, and upwards, on the other, through the Old Red Sandstone and the Carboniferous Limestone, to the workable Coal Measures. Both stratigraphically and palæontologically the place in the scale of the Niagara graveyard can be definitely determined; and a superficial deposit on the heights in its immediate neighborhood shows that the river did not begin its work of excavation among its long extinct shells, trilobites, and corals, until after not only the great Palæozoic, but also the Secondary and Tertiary divisions had been laid down, and the recent period ushered in. The superficial shells of the adjacent heights belong to the Pleistocene age, and show that in even that comparatively modern time the lower lands of Upper Canada were submerged beneath the level of the ocean, and that a series of deep seas, connected by broad sounds, occupied the place of the great lakes. Not until the last upheaval of the land was the river now known as the St. Lawrence called into existence, to begin its work of excavation; and ere that event took place, fully ten miles of fossiliferous rock had been deposited on the earth's surface, charged with the remains of many succeeding creations. The deposit through which the St. Lawrence is slowly mining its way is older than the river itself by the vast breadth of the four Tertiary periods, by that of all the Secondary ages,--Cretaceous, Oolitic, and Triassic,--by the periods, too, of the Permian system, of the Carboniferous system, of the Old Red system, and of the uppermost beds of the Upper Silurian system. But a