COAL MEASURES OF N.S.W. AND ASSOCIATED ERUPTIVE ROCKS. 265 



rests on volcanic tuff, and is capped first by 300 feet of fine tuff, 

 then by 1000 feet of diabasic andesite. This section is exposed 

 at the Seven Mile, on the Raymond Terrace to Stroud road. 

 Formerly it appeared to me that this seam, as well as the over- 

 lying diabasic andesites, belonged to the top of the Rhacopteris 

 beds. Having lately however found undoubted specimens of 

 Glossojrteris, identified by Mr. R. Etheridge, junr., as such, in the 

 Seven Mile Coal-seam, I think the seam should be referred to 

 some part of the Glossopteris Series, and the overlying volcanic 

 rocks may in that case be correlated with the Kiama Series in the 

 Illawarra Coal-field. 



The lavas in the Hunter River Coal-field near Raymond Terrace, 

 like those of Illawarra and of the Bowen River, contain a good 

 deal of red laumonite in their joints. Copper however has not 

 yet been detected in the Raymond Terrace lavas. One point of 

 eruption of the latter lavas is observable in a hill called Paddy's 

 Sugarloaf, thirteen miles from Raymond Terrace towards Stroud. 

 Part of the old crater is there capped by a thin sheet (about eight 

 feet thick) of a beautiful banded rhyolite, which has now been 

 rendered felsitic through devitrification. The exact age of the 

 contemporaneous volcanic series of the Bowen River in Queens- 

 land is not known, but apparently it underlies the Lower Marine 

 Series, and may be of Permo-Carboniferous age. Like the Kiama 

 Series it contains copper, in the form of carbonate, as well as 

 laumonite. 



(ii.) Subsequent. The Hunter River, Sydney, Illawarra, 

 Mittagong, and Blue Mountain Coal-fields have been intruded 

 subsequent to their deposition by a variety of eruptive rocks, 

 chiefly dolerites, which in places, as near Mittagong, pass into 

 syenite. In the Hunter River Coal-field, the Greta, Tomago, and 

 Newcastle measures have been cut by dolerite dykes of a later date 

 than the intrusive red granitic quartz-porphyries of Port Stephens, 

 as at Morna Point. At the latter locality, the quartz-porphyres 

 are seen to be intersected by the dolerites. In the Stockton mine 

 the coal in the Borehole Seam has been much damaged by the 

 dolerite ; and the lower Tomago Seams have also suffered con- 

 siderably from the same cause at Hexham and Ash Islands, being 

 converted into natural coke or being completely cindered in places. 

 In the Illawarra and Mittagong districts large areas of coal have 

 been injected with flat sheets of eruptive rock. These have 

 however not altogether destroyed the coal, but have converted it 

 chiefly into a natural coke, which may yet have an economic value. 



Near Bulli, and at Cambewarra near Nowra, are remarkable 

 dykes of what may provisionally be termed gabbro-dolerites. 

 These contain large crystals of hornblende over an inch in diameter, 

 and nests of olivine two to three inches in diameter, enclosed in a 



