254 



SCIENCE. 



[Vol. XVI. No. 405 



this polar region the SDOwfall must be taken into account as 

 well as the ash deposit and the lava-flow. It may be thought 

 that any volcanic ejecta would speedily melt the snow upon 

 which they fell, but this does not by any means necessarily 

 follow. Volcanic ash, the most widespread and most abun- 

 dant material ejected, falls comparatively cold, cakes, and 

 then forms one of the most effective non-conductors known. 

 When such a layer, a few inches thick, is spread over snow, 

 even molten lava may flow over it without melting the snow 

 beneath. This may seem to be incredible, but it has been 

 observed to occur. In 1828, Lyell saw on the flanks of Etna 

 a glacier sealed up under a crust of lava. Now, the Antarc- 

 tic is the region of thick-ribbed ice. All exposed surfaces 

 are quickly covered with snow. Snow-falls, ash-falls, and 

 lava-flows must have been heaping themselves up around 

 the craters during unknown ages. What has been the re- 

 sult? Has the viscosity of the ice been modified by the in- 

 tercalation of beds of-rigid lava and of hard-set ash? Does 

 the growing mass tend to pile up, or to settle down and 

 spread out? Is the ice wasted by evaporation, or does the 

 ash layer preserve it against this mode of dissipation? These 

 interesting questions can be studied round the south pole, 

 and perhaps nowhere else so well. 



Another question of interest, as bearing upon the location 

 of the great Antarctic continent, which it is now certain ex- 

 isted in the secondary period of geologists, is the nature of 

 the rocks upon which the lowest of these lava-beds rest. If 

 they can be discovered, and if they then be found to be sedi- 

 mentary rocks such as slates and sandstones, or Plutonic 

 rocks such as granite, they will at once afford us some data 

 to go upon, for the surface exposure of granite signifies that 

 the locality has been part of a continental land sufficiently 

 long for the weathering and removal of the many thousands 

 of feet of sedimentary rocks which of necessity overlie crys- 

 talline rocks during their genesis; while the presence of 

 sedimentary rocks implies the sometime proximity of a con- 

 tinent, from the surfaces of which alone these sediments, as 

 rainwash, could have been derived. 



As ancient slate rocks have already been discovered in the 

 ice-clad South Georgias, and as the drag-nets of the "Erebus" 

 and the "Challenger'' have brought up from the beds of 

 these icy seas fragments of sandstones, slates, and granite, 

 as well as the typical blue mud which invariably fringes con- 

 tinental land, there is every reason to expect that such strata 

 will be found. 



Wherever the state of the snow will permit, the polar 

 mountains should be searched for basaltic dikes, in the hope 

 that masses of specular iron and nickel might be found 

 similar to those discovered by Nordenskiold at Ovifak, in 

 North Greenland. The interest taken in these metallic 

 masses arises from the fact that they alone, of all the rocks 

 of the earth, resemble those masses of extra-terrestrial origin 

 which we know as meteorites. Such bodies of unoxidized 

 metal are unknown elsewhere in the mass, and why they are 

 peculiar to the Arctic it is hard to say. Should similar 

 masses be found within the Antarctic, a fresh stimulus would 

 be given to speculation. Geologists would have to consider 

 whether the oxidized strata of the earth's crust thin out at 

 the poles; whether in such a case the thinning is due to 

 severe local erosion, or to the protection against oxygen 

 afforded to the surface of the polar regions by their ice-caps; 



or to what other cause. Such discoveries would add some- 

 thing to our knowledge of the materials of the interior of our 

 globe and their relation to those of meteorites. 



Still looking for fresh knowledge in the sarne direction, a 

 series of pendulum observations should be taken at points as 

 near as possible to the pole. Within the Arctic Circle the 

 pendulum makes about 240 more vibrations per day than it 

 does at the equator. The vibrations increase in number 

 there, because the force of gravity at the earth's surface is 

 more intense in that area; and this, again, is believed to be 

 due to the oblateness of that part of the earth's figure, but it 

 might be caused by the bodily approach to the surface at the 

 poles of the masses of dense ultra-basic rocks just referred 

 to. Thus, pendulum experiments may reveal to us the 

 earth's figure; a,nd a series of such observations recorded, 

 from such a vast and untried area, must yield important 

 data for the physicist to work up. We should probably learn 

 from such investigations whether the earth's figure is as 

 much flattened at the Antarctic as it is known to be at the 

 Arctic. 



We now know that in the past the north-polar regions 

 have enjoyed a temperate climate more than once. Abun- 

 dant seams of paleozoic coal, large deposits of fossiliferous 

 Jurassic rocks, and extensive eocene beds, containing the 

 remains of evergreen and deciduous trees and flowering 

 plants, occur far within the Arctic Circle. This circum- 

 stance leads us to wonder whether the corresponding southern 

 latitudes have ever experienced similar climatic vicissitudes. 

 Conclusive evidence on this point it is diflScult to get; but 

 competent biologists who have examined the floras and 

 faunas of South Africa and Australia, of New Zealand, 

 South America, and the isolated islets of the Southern Ocean, 

 find features which absolutely involve the existence of an 

 extensive Antarctic land, — a land which must have been 

 clothed with a varied vegetation, and have been alive with 

 beasts, birds, and insects. As it also had had its fresh-water 

 fishes, it must have had its rivers flowing and not frost- 

 bound, and in those circumstances we again see indications 

 of a modified Antarctic climate. Let us briefly consider 

 some of the evidence for the existence of this continent. 

 We are told by Professor Hutton of Christchurch that 44 per 

 cent of the New Zealand flora is of Antarctic origin. The 

 Auckland, Campbell, and Macquarie Islands all support Ant- 

 arctic plants, some of which appear never to have reached 

 New Zealand. New Zealand and South America have three 

 flowering plants in common, also two fresh-water fishes, five 

 seaweeds, three marine crustaceans, one marine mollusk, and 

 one marine fish. Similarly New Zealand and Africa have 

 certain common forms; and the floras and faunas of the 

 Kerguelen, the Crozets, and the Marion Islands are almost 

 •identical, although in each case the islands are very small 

 and very isolated from each other and from th§ rest of the 

 world. Tristan d'Acunha has 58 species of marine MoHusca, 

 of which number 13 are also found in South America, six or 

 seven in New Zealand, and four in South Africa (Button's 

 Origin of New Zealand Flora and Fauna). Temperate 

 South America has 74 genera of plants in common with New 

 Zealand, and 11 of its species are identical (Wallace's Island 

 Life). Penguins of the genus Eudyptes are common to 

 South America and Australia (Wallace's Dist. of Animals, 

 1399). Three groups of fresh-water fishes are entirely con- 



