BY T. W. EDGEWORTH DAVID. 265 



As shown in the upper section on Plate xvi. a sheet of trachyte at 

 least 20 feet thick caps the ridge overlooking Wantialable Creek. 

 Below this is a thickness of about 30 feet of trachyte tuff varying 

 in texture from fine to coarse. A remarkable rock succeeds 

 which I have termed a silicified trachyte tuff, 1| ft. to 2 ft. thick. 

 This rock has already been ably described by Mr. G. W. Card,* 

 the Mineralogist to the Geological . Survey of the Department of 

 Mines. 



Underlying this is another also very remarkable bed of 

 trachyte tuff, almost exclusivel}'' composed of translucent crystals 

 of sanidine, from a fraction of an inch up to ij an inch in diameter. 

 The crystals exhibit their usual tabular habit, the clinopinacoid faces 

 being extensively developed. The bed being only loosely coherent, 

 the rain washes quantities of the larger sanidines out of it, and 

 forms with them miniature snow-white talus slopes. 



Next follows the bed of diatomaceous earth, 3 feet 9 inches thick; 

 then come 19 feet 3 inches of strata, chiefly trachyte tuffs, 

 resting on the sui'face of a sheet of vesicular trachyte. Half-a- 

 mile higher up the creek, the lower section shown on Plate xvi. 

 may be studied. It resembles the section above quoted, but in 

 addition fossil leaves occur on a horizon immediately above and 

 intimately associated with the diatomaceous earth, as was shown 

 me by Mr. "VV. L. R. Gipps. We had here the good fortune to dis- 

 cover a fossil leaf fairly well preserved in the tine tuft', which Mr. R. 

 Etheridge, jun., and Mr. W. S. Dun, Assistant Palaeontologist to 

 the Geological Survey, identify as Cinnamomum Leichhardtii, 

 Ettingshausen. (See Plate accompanying this" paper). This leaf 

 is elsewhere in Australia associated with Eocene deposits. 



The age therefox'e of the Diatoms and of the freshwater sponge 

 spicules associated with them at this spot may, I think, be pro- 

 visionally set down as early Eocene or late Cretaceous. 



I have purposely abstained from attempting a detailed descrip- 

 tion of the different species of Diatoms and sponges represented 



Records Geol. Surv. N.S. Wales. Vol. iv. Pt. iii. pp. 115-117. Plate 

 By authority. Sydney. 1895. 



