PRESIDENTIAL ADDRESS — SECTION E. 241 



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 ques- 

 tions 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 existed 

 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 sedimentary 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 sedi- 

 mentary rocks which of necessity overlie crystalline rocks 

 during their genesis ; whilst the presence of sedimentary rocks 

 implies the sometime proximity of a continent, from the sur- 

 faces 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 granite in other islets, 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 in- 

 variably fringes continental land, there is every reason to 

 expect that such strata will be found. 



Wherever the state of the snow will permit the polar moun- 

 tains should be searched for basaltic dykes, in the hope that 

 masses of specular iron and nickel might be found, similar to 

 those discovered by Nordenskiold at Ovifak, in North Green- 

 land. 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 pro- 

 tection against oxygen afforded to the surface of the polar 

 regions by their ice-caps, or to what other cause. Such dis- 

 coveries would add something 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 same direction, a 

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