. British Antarctic expedition, 1907-9, under the command of Shackleton : reports on the scientific investigations ; geology. ime. In British Guiana the quartz dolerites,occurring there as dykes and sills, are considered to be intruded in Mesozoic time. Mr. Benson compares also with the Antarctic dolerites the quartz dolerites nearNew York forming the famous palisades on the Hudson. These intrude the Newarksystem, perhaps of Trias-Jura age. Dr. G. T. Prior has shown in his account of the quartz dolerites of Natal andZululand that they are strikingly similar to those of the palisades and o
. British Antarctic expedition, 1907-9, under the command of Shackleton : reports on the scientific investigations ; geology. ime. In British Guiana the quartz dolerites,occurring there as dykes and sills, are considered to be intruded in Mesozoic time. Mr. Benson compares also with the Antarctic dolerites the quartz dolerites nearNew York forming the famous palisades on the Hudson. These intrude the Newarksystem, perhaps of Trias-Jura age. Dr. G. T. Prior has shown in his account of the quartz dolerites of Natal andZululand that they are strikingly similar to those of the palisades and of theAntarctic. There is here a strong probability of the Antarctic quartz dolerites and thoseof Tasmania forming part of one great tectonic hinge. If, as seems probable, theTasmanian dolerites were intruded in Cretaceous time, the age of the Antarcticdolerites would be also Cretaceous. They serve, therefore, to fix the upward limit forthe date of the Beacon Sandstone. Thus the coniferous wood practically limits itdownwards to Carboniferous, while the quartz dolerite places its upward limit belowthe Cretaceous. PLATE LXXXIII. 0 1 2 3 4- I 1 M ! [ INCHES O 1 2 3 4 S 6 7 8 9 lO 1 _J^ i 1 , CENTIMETERS Fig. 1. TYPICAL WEATHERED SURFACE OF KENYTE LAVASHOWING ANORTHOCLASE CRYSTALS IN RELIEF
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