76 



instances to 90°. Accordingly every 30,000 feet of strata in thickness 

 now represents a ground surface of about one statute mile." The author 

 failed to observe any unconformity in the superposition of the strata for 

 a distance of from two to three miles in the channel of the South Para 

 in tbe locality named, but describes the phenomenon of inversion as ex- 

 hibited by a band of highly metamorphosed sandstone about one mile to 

 the east from the junction of the Para and the Tenefete Creek. " To the 

 east of the axis of inversion as you ascend the bed of the river, you will 

 pass over bands of comparatively unaltered clay slate, micaceous and 

 gneissic schists, intercalated with quartz reefs and bands of quartzites for 

 several miles in succession, over the existing surface, and still the 

 easterly dip of about 60° and conformity of bedding prevail. The reason 

 for this general precision of easterly dip throughout the western slope of 

 the Barossa Hills is stated to be, because tbat range is merely the eastern 

 buttress and spring of a once stupendous arch of strata, which in times 

 long since past extended far to the west in a grand anticlinal curve." 



The author next discusses the effect of pressure and nuclear heat in 

 the production of fissures ; and combats the opinion that they are caused 

 by earthquakes ; and proceeds to describe the various methods by which 

 it is conceived that fissures once existing in the rocks, as empty chasms, 

 have been subsequently filled in with quartz and other vein stuffs ; and 

 endeavours to show that the vein deposits are due to hydrothermal action. 

 In connection with the latter branch of the subject, he seeks to con6rm 

 Mr. Selwyn's opinion that alluvial nuggets of gold were products of com- 

 paratively recent infiltrations through the detrital accumulations in 

 which they are found. He writes : — " I have in my possession a nugget 

 taken from the alluvial workings in Hamlin's Grully, Barossa, which 

 shows strong indications of its formation having taken place in the mould 

 from which it was taken. It weight is about 69 grains, it measures 

 about one inch in length, by about five-sixteenths at the broader end, in 

 shape it is not unlike the spearhead of a warrior of the Middle Ages 

 denuded of its point. The thoroughly defined impressions which it 

 retains of the die, and the sharpness of its edges preclude the idea of its 

 having been transported." 



