The unstratified Plutonic rocks are considered to form, as we have intimated, the common base of the stratified beds all over the globe. With them, however, we have little to do in this place. Our labours commence with the stratified, and we should even have excluded the so-called “Azoic,” had not that term been recently subjected to considerable restriction by the discovery of organic remains in some of its members; and, as it is still likely, by further researches, to be totally absorbed into the Palæozoic system, we append an ideal section representing the sequence of formation of the most ancient groups of fossiliferous rocks, with the relative position of those primordial conglomerates, flags, and schists in which as yet no organic remains have been found. Whether, at the vastly remote period at which those isolated masses, still ranked as Azoic, were formed, the advent of life had really not taken place on our planet, or whether those masses are the few remnants of a still older stage of our world than any presented to us by the recognised series of fossiliferous rocks, has yet to be determined by the investigations of geologists—but in their massiveness and their vast age they must ever be regarded with veneration and wonder.