Page:Transactions NZ Institute Volume 10.djvu/33

Rh of the globe was at that epoch more equable, if not imiversally higher, which may reasonably be presumed to have been the case; more especially if, as it has been suggested, climatic zones did not exist until the commencement of the tertiary era.

The further careful observations are extended and ice-marks sought for, where they ought to be found in the same latitudes, if the ice-cap covered one hemisphere in all meridians at the same time, the less strong appears the evidence of the struggle for life, it is alleged that animals and plants underwent in the limited unglaciated regions proposed to have remained during one portion of the quaternary period; a struggle which proved too great for many pre-existing forms, and led to their extinction, as some of the advocates of recurring eras of universal giaciation assert most probably effected the destruction of the giant Saurians, once the domineering tenants of land and sea in all parts of the world; whether that tenancy was altogether synchronous in both hemispheres is an interesting question if its expiry was due to an age of ice; it may well be doubted whether it was.

So far as observations have been made in the southern hemisphere, there are no records of a greater amount of frost than inscribes its marks to-day. South Georgia, in latitude 54° S., is frequently referred to as an evidence of what local influences may bring about in the way of glaciation; exposed to the full force of the berg-laden antarctic current it is wrapped in snow and ice nearly to the water's edge all the year, whilst fifteen degrees to the west forests of beech and fuchsia clothe the sides of the mountains, and humming-birds flit over the glaciers in the Straits of Magellan.

The condition of this island and of Sandwich Island is "a warning," Sir Charles Lyell says, against concluding that giaciation must have been universal over one hemisphere at the same time. The opinion expressed by Professor Agassiz and others respecting the apparent work of ice in the Amazon Valley may nevertheless be correct. A berg-bearing current may have swept over the submerged eastern plains of South America, and the temperature lowered over a broad belt in that meridian; whilst Australia, New Zealand, and South Africa were subjected to no such influence.

The work that is being done by southern currents now must equal in magnitude that performed by the ocean streams which deposited the northern drift, now in one now in another meridian, over the submerged lands of Europe and America. Flowing up to the north, they carry their chilled waters under tropical seas whose surface temperature is 80° to 85°, not only up to the equator, but on, it has been most unexpectedly discovered, into the temperate zone as far as the Bay of Biscay—working, of course, great changes in the submarine inhabitants of vast areas—as similar currents have been doing in all time past, as the great underset flowed