92 THE BINaERA DIAMOND FIELD. 



But we have a full account of the geology of the diamond- 

 bearing district detailed in the above-mentioned paper by Messrs. 

 Norman Taj-lor and Thomson, and from it we shall see that the 

 Mudgee and Bingera districts have many points of resemblance. 



The Mudgee diamond Avorkings are distant some 170 miles 

 south of Bingera, on the Cudgegong River, which runs into the 

 Macquarie Eiver, and that again into the Darling River. 



Diamonds -were first discovered here in 1867 by the gold dig- 

 gers, w-ho neglected them for some time, but in 1869 they were 

 worked pretty extensively. The localities lie along the river 

 in the form of outliers of an old river drift, at varying distances 

 from the river, and at heights of 40 feet or so above it. These 

 outliers are capped by deposits of basalt, hard and compact, and 

 in some cases columnar. This basalt is regarded by Mr. Taylor 

 as of Post-Pleiocene age, but this has not been determined directly 

 by any fossil evidence. 



The great denudation wdiich the district has sustained is at once 

 apparent from the drift, together wdth its protective covering of 

 basalt, having been cut up into these isolated patches or outliers. 



The remains of the drift can still be traced for some 17 miles 

 up the river, and in parts it still retains a thickness of 70 feet. 



The patches which were worked, as enumerated in the above- 

 mentioned paper, are as follows : — Jordan's Hill, 40 acres ; Two- 

 mile Flat, 70 acres ; Rocky Ridge, 40 acres ; Horseshoe Bend, 20 

 acres ; Hassall's Hill, 340 acres. Total, 510 acres. 



A peculiar deposit of crystalline cinnabar was found in one 

 patch. 



lu the above localities the drift has invariably been met within 

 tunnelling under or sinking through the basalt, and in places 

 w'hei-e the basalt had been denuded away the drift has either 

 disappeared or has been scattered over the neighbourhood. 



Ko diamonds have been been found in the riAcr bed, except in 

 places where the diggers have dischai'ged the drift into the river 

 when washing for gold. 



The basalt when not resting on the drift frequently lies upon 

 metamorphic shales, slates, sandstones, or greenstone. 



The general formation of the neighbourhood is regarded as 

 Upper Silurian, with overlying outliers of undoubtedly carbon- 

 iferous age. 



The rocks in the vicinity are nearly vertical, with a general 

 strike of N.X.AY., and consist of red and yellow coarse and fine 

 grained indurated sandstones; thin white platy argillaceous shales; 

 pink and brown fiue-gi'ained sandstone, banded with purple stripes; 

 slates and hard metamorphic schists ; hard brecciated conglome- 

 rate, containing limestone nodules, flint, and red felspar in a 

 greenish silicious base. And with these occur dykes and ejections 

 of intrusive ereeustone. 



