The Late Pahæozoic Glaciation

Abstract

PROF. SCHUCHERT, in his recent paper on the late Palæozoic ice age (Bulletin of the Geological Society of America, vol. 39, pp. 769-886), has strenuously fought for the view that the ice age is not older than Middle Permian. I have read with interest Dr. H. Dighton Thomas's article in NATURE (June 22, 1929, p. 946), and both I and, I think, all my colleagues of the Geological Survey of India, are in agreement with Dr. Thomas's views. It appears quite impossible to regard the whole of the Productus Limestone of the Salt Range as belonging to the Upper Permian only. I prefer to regard the Upper Productus Limestone of the Salt Range (Chidru beds) as Upper Permian, the Middle Productus Limestone with Xenaspis carbonaria as of Middle Permian age, and the Lower Productus Limestone with Spirifer Marcoui as Lower Permian. With the Middle Productus Limestone may be correlated, according to C. Diener, the bulk of the Zewan beds of Kashmir, and the fauna of exotic block No. 1 of Chitichun (Pal. Ind., New Ser., vol. 5, Mem. 2, p. 110). Diener places the Gangamopteris horizon of Kashmir in the Lower Permian or Artinskian (ibid. p. 111).