One of the first difficulties that suggests itself in the consideration of this particular dogma, this narrow zone to which organic life had to withdraw in post-pliocene times—is that during this epoch, which it appears was subsequent to, if not coincident with, the time when men first commenced to talk sense in Lemuria—i.e., 100,000 years ago—although the circulation of the equatorial currents must have ceased, the chilled waters from both polar regions continued their course with increased force, until they had invaded all submarine depths, and all forms of organic life unable to adapt themselves to the change, or unable to reach the place of refuge, perished.
It would be difficult, however, to prove that polar marine currents have ever operated over greater areas or with more force than they do to-day, and frost now stretches its rigid winding sheet over tracts of land not long since, geologically speaking, teeming with animal life and covered with luxuriant vegetation, whilst in the same latitudes it has relaxed its grasp over others which for ages had been locked in its stern embrace.
Ever varying in their direction during the lapse of years, mighty ocean streams have borne along then islands of ice loaded with the debris of rocks from glaciated regions, strewing the ocean floor as liberally now as in any previous era, dropping boulders to-day upon beds being laid down at the bottom of the sea, to be the chalk hills of future continents, and at still greater abysmal depths of red clay (both composed of exuviæ of minute organisms, falling to the bottom incessantly through countless centuries; a discovery the more astonishing when it is considered that this lifeless red clay, identically the same as that of the dry land so familiar to us, and so long a profound mystery, is seemingly chiefly derived from the insoluble residue of these Foraminifera, which is estimated at about only two per cent.) changing the climates of adjacent lands, and causing ever varying migrations of their fauna and flora, as well as of the life beneath the waters, in all time past.
The glaciers in present elevated regions, the Cordilleras of South America and New Zealand, the Himalayas, the Alps, the Caucasus, may not be greater than those which descended from the lofty mountains, higher perhaps than any of these that rose above the plams covered with the forests of the carboniferous era.
Under the pluvial conditions which then probably obtained, judging from the climates in which analogous vegetation flourishes at the present time, we may conclude they are not. At all events the marks of ice-action are to be seen, proving that in those days, as well as in our own, certain portions of the earth's surface had their share of giaciation, however much the general aspect of the fauna and flora may suggest that the temperature
