Voyages of Discovery and Survey. 317 



comparison of the fossils from the Chair of Kildare with those ob- 

 tained from the limestone of Courtown, county Wexford, leads Pro- 

 fessor E. Forbes to regard it as highly probable that the limestones 

 are equivalents, and that both are representatives in Ireland of the 

 Bala limestones, a point of much importance as regards the accumu- 

 lations during the same time in the British area. 



Contributions to Geology, by the late Voyages of Discovery 

 and Survey. — The publication during the past year of three voyages 

 of our countrymen has added to our knowledge of the geological 

 structure of the earth's surface in distant places. The voyage of 

 Sir James Boss to the Antarctic regions has proved, not only the 

 great extent of a mass of land in the South Polar regions, but also 

 that volcanic forces are still in full activity there. A mountain esti- 

 mated to rise 12,000 feet above the sea, and named Mount Erebus, is 

 described as throwing out jets of dense smoke to the height of 1500 

 and 2000 feet, the diameter of the jets being estimated at 200 to 

 300 feet. Even streams of lava were thought by some persons to be 

 ejected. Not far from Mount Erebus another mountain, named Mount 

 Terror, exhibited a form leading to the inference that it was an ex- 

 tinct volcano, and crater-like hillocks were observable on its sides. 



An icy barrier for the most part prevented access to the land, but 

 wherever a landing was effected igneous rocks alone were found, and 

 all the fragments or pebbles obtained from icebergs, and by sound- 

 ings, were of the same character, granitic rocks being discovered 

 among them. 



It is not a little interesting to consider the different conditions 

 under which rocks would be placed in a region like that of Victoria 

 Land, and in those parts of the world where snow never falls and 

 frost is not felt, as also in those exposed alternately to the cold of 

 winter and the heats of summer. On the Antarctic land no great 

 river appears to bear detritus into the sea, and decomposition from 

 the action of many atmospheric influences, such as aid the disinte- 

 gration of rocks in temperate and tropical regions, can be little felt. 

 As far as was seen by our navigators a great mantle of snow covers 

 all, with the exception of some bare spots, probably either too pre- 

 cipitous to be thus enveloped, except by sufficient accumulation 

 around them, or still too warm, after flowing as lava currents, to 

 permit a covering of snow. 



Though wo can look to little else, for the wearing away of the 

 land, than the action of the breakers upon the portions of the coast, 

 which may for a time be free from ice, with such aid as any marked 

 difference of temperature, during a very short period in the summer 

 of these re^ons can give, by detaching pieces of rock from the cliffs, 

 yet the volcanoes may throw mineral matter into the sea, to be dis- 

 tributed by tidal streams or oceanic currents. There is no reason 

 to suppose that lofty volcanoes, like Mount Erebus, do not occa- 



VOIi. XLV. NO. XC. — OCTORKK 1848. Y 



