But the marine deposits of the present creation have been, perhaps, accumulating more rapidly than those of our lakes, forests, or rivers? Yes, unquestionably, in friths and estuaries, in the neighborhood of streams that drain vast tracts of country, and roll down the soil and clay swept by the winter rains from thousands of hill-sides; but what is there to lead to the formation of sudden deposits in those profounder depths of the sea, in which the water retains its blue transparency all the year round, let the waves rise as they may? And do we not know that, along many of our shores, the process of accumulation is well nigh as slow as on the land itself? The existing creation is represented in the little land-locked bay, where the crustacea harbor so thickly, by a deposit hardly three feet in thickness. In a more exposed locality, on the opposite side of the promontory, it finds its representative in a deposit of barely nine inches. It is surely the present scene of things that is in its infancy! Into how slender a bulk have the organisms of six thousand years been compressed! History tells us of populous nations, now extinct, that flourished for ages: do we not find their remains crowded into a few streets of sepulchres? 'Tis but a thin layer of soil that covers the ancient plain of Marathon. I have stood on Bannockburn, and seen no trace of the battle. In what lower stratum shall we set ourselves to discover the skeletons of the wolves and bears that once infested our forests? Where shall we find accumulations of the remains of the wild bisons and gigantic elks, their contemporaries? They must have existed for but comparatively a short period, or they would surely have left more marked traces behind them.