Discussion

Abstract

Dr. R. G. S. HUDSON called the author’s attention to recent discoveries of the field geologists of the Iraq Petroleum Company in south-western Oman (lat. 21° 02.3’: long. 57° 36.2’) which had considerable bearing on the Permian palaeogeography of Gondwanaland. There a group of sandstones, about 64 metres thick, contained boulder-beds of igneous and sedimentary rocks. Immediately above and below these sandstones were sandy limestones with Permian faunas, the upper one containing Metalegoceras aff. clarkei Miller of Sakmarian–Artinskian age. The boulder-beds were considered to be of glacial or aqueo-glacial origin, the boulders being derived mainly from the Pre-Cambrian of the Arabian massif. The succession could be compared with that of the Permo-Carboniferous of the Salt Range but was most similar to the Sakmarian and basal Artinskian of Western Australia, where the Metalegoceras limestones had the same relationship to the tillites as in Oman. Dr. A. N airn said that palaeomagnetic measurements, treated statistically (1953, R. A. Fisher, Proc. Roy. Soc. A, 217, 295–305), gave results in terms of the magnetic inclination and declination of the sampling site which could be related to the geographic co-ordinates. There was, therefore, an independent check on the position of any area relative to an ancient pole and one which should correlate with palaeoclimatic belts. In the northern hemisphere this had invariably been the case in the area from which the samples were collected, and Opdyke (1956) had further shown that the wind directions of dune-bedded Permian and Triassic sands of Britain and North