Similarity In Rocks Of Antarctica, South Africa

Press, Volume CII, Issue 30043, 30 January 1963, Page 3

Similarity In Rocks Of Antarctica, South Africa

The thickness and finer details of lava flows in the plateau area between the Rennick and Aviator glaciers in the north-west Ros Dependency are very similar to those of Rhodesia and South Africa, the Christchurch district geologist, Geological Survey, Department of Scientific and Industrial Research (Mr H. S. Gair) said yesterday. Mr Gair, who has just returned from making a geological survey of the plateau, was for some years a member of the Northern Rhodesia Geologicai Survey. The sOoOft-thick lavas of the plateau contained zeolites, agates, chalcedomy, and a little calcite, just as did those of southern Africa, said Mr Gair. In one of the sandstone layers interbedded among the lava, the surveyors discovered fossil tree-trunks and roots. The area was not, however, as interesting geologically as had been expected, Mr Gair added, partly because the huge thicknesses of beacon

sandstone which in southern Africa and in many parts of Antarctica underlay the lavas were almost absent in the Rennick plateau region, their maximum thickness being only about 30ft. In other areas, sediments of several thousand feet thickness had yielded many interesting fossils, both plant and animat In the sandstones of the plateau, carbonaceous material had been discovered but no recognisable fossils. The basement rocks of the area were almost all granites, making for a sameness in the geology which contributed to his disappointment, Mr Gair said. The granites were relieved in one place, however, by schists associated with an extensive area of marble. The marble seam waa several hundred yards across, but so contorted that there was difficulty in relating it to the schists. These basement rocks were all probably pre-Cambrian, with the granites younger than the schists and marbles. The beacon sandstone and the

lavas were probably Triassic or Jurassic. Along the coast was a line of volcanoes, mostly probably extinct or dormant, of a much younger geological age than the plateau lava beds. The line was the same as that on which mounts Erebus and Terror stand. Of the volcanoes in the northwest area, only the southernmost, Mount Melbourne, has yet been named.