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l^OTES EEGAEDINa THE EXISTENCE OF LOWER 

 COAL MEASURES AT PORT CYGNET AK'D 

 HAREPIELD. 



By E, M. Johnston, F.L.S. 



PORT CYGNET. 



Recently the author has had an opportunity for 

 examining the geological features of the country lying 

 between Port Cygnet, Garden Island Creek, Mount 

 Cygnet, and Long Bay, The evidences gathered have 

 enabled him to determine that the Mount Cygnet coal 

 measures are the equivalents of the Adventure Bay group, 

 and consequently they must be classed with the upper 

 division of the lower coal measures. The plant remains 

 associated with the coal seam are very abundant, although 

 almost restricted to one form, viz., Vertebraria australis. 

 The only other associate discovered rarely is a dwarf form of 

 Gangamopteris, probably identical with G. spathulata, M'Coy. 

 The absence of Nceggerathiopsis, Glossopteris, and ScMzoneura, 

 of the lower division — so common in the Mersey on the one 

 hand — and the absence of PhyllotJieca and Sphenopteris, so 

 common in the upper division of the lower coal measures, as 

 in the Newcastle coal beds of New South Wales — on the other 

 hand — suggest that the Mount Cygnet beds form an inter- 

 mediate group ; the typical plant, Vertebraria australis, of the 

 group indicating the closer affinity with the Newcastle group. 

 The coal beds of Mount Cygnet immediately overly the upper 

 palaeozoic marine beds, and conform with them in the dip to 

 the south. This position is the esact parallel of the Adven- 

 ture Bay coal measures. There is evidently a very great 

 strati graphical break, therefore, between the Mount Cygnet 

 coal measures and those of the Sandfly under Mount Grey, 

 lying against the same greenstone axis at a greater height a 

 few miles to the north. 



The crest of Mount Cygnet is composed of greenstone, as 

 in the main spur forming the divide running southward from 

 the slopes of Mount Wellington to its termination near 

 Three Hut Point. From Mr. Ford's mill at Garden Island 

 Creek it presents a low, rounded, conical appearance, rising 

 to a height of about 900 feet from a horizontal sandstone 



