64 COALFIELDS AND COLLIERIES OF AUSTRALIA. 



basin is probably in the neighbourhood of Parramatta. The 

 Permo-carbonifero^g system of rocks is separated from the 

 Devonian by a strongly marked unconformity. After the 

 folding' of the Carboniferous and Upper Devonian formations, 

 a great land building- epoch in the history of the Australian 

 continent caused ranges to become established west of the 

 present site of the Blue Mountains ; sediments derived from 

 the wearing down of the former then began to be deposited 

 in the shallow seas, extending from near Penritn to the con- 

 tinental shelf. These constituted the strata of the Lower 

 Marine Series (Permo-carboniferous), Prof. David continues, 

 ''Swampy or lacustrian conditions succeeded, and the Greta 

 coal-measures were laid down over an area about two hundred 

 miles long, from north to south, and from thirty to forty 

 miles from east to west. A considerable subsidence ensued, 

 during which the waters of the Pacific penetrated to at least 

 as far inland as Mount Lambie, about seventy-two miles 

 inland from the present coast. The subsidence amounted to 

 a maximum of about five thousand feet in the Maitland 

 district, and two thousand five hundred feet in the Illawarra 

 district. The strata of this epoch belongs to the Upper Marine 

 Series. The cessation of the subsidence was accompanied by 

 volcanic eruptions, most extensively developed in the Kiama 

 neighbourhood, but represented also on a smaller scale by the 

 volcanic rocks near Rylston. Swampy conditions returned on 

 a larger scale than ever, and the Bulli-Newcastle coal measures 

 were formed in the Blue Mountains area, while in the New- 

 castle area, a middle group of coal measures (The Tomago 

 Series) was developed as well, being interstratified between 

 the top of the Upper Marine Series and the best of the 

 Dempsey beds, which underlie the Newcastle coal-measures. 

 Tlie abundance of fossil trees referable to Arati carioxylon,^ 

 many preserved in the form of stumps in situ in the formation 

 in which they grew, is clear proof that the conditions under 

 which the Newcastle-Bulli coal measures grew were terrestrial 

 rather than marine. The formation of the last of the coal 

 senms of the Newcastle-Bulli series closes the history of the 

 Palaeozoic era in New South "Wales." 



For full details of the geology of the Northern coal-field, 

 the reader is referred to the excellent monograph by Prof. 

 T. W. E. David on "The Geology of the Hunter Eiver Coal 

 Measures, New South Wales," recently published by the 

 Department of Mines and Agriculture. 



transferred by Mr. E. A. N. Arber, of Cambridge 

 University, to the genus Dadoxylon. 





