158 GEOLOGY OF THE GLENDONBROOK DISTRICT, 



of about 1,000 feet ; the Upper Marine Series have practically their 

 full development (4,800 feet) not far away, so it seems not unrea- 

 sonable to put the throw of the fault somewhere in the neighbour- 

 hood of 5,800 feet. The Webber's Creek fault trends roughly E.-W. 

 in its western extension, and swings round to a S.W.-N.E. trend 

 towards its eastern end. It extends, on the map, from near West- 

 brook to near "The Gap," on the road from Singleton to Gresford. 

 It is an extensive fault, and its existence is indicated mainly by 

 the following points: — 



(a) The southern boundary of the Webber's Creek Series is a 

 fairly regular line, and that Series is in contact with beds of dif- 

 ferent ages at different points, namely, Upper Carboniferous at 

 Tamby Creek, Permo-Carboniferous from Tamby Creek to One- 

 Tree Hill, Carboniferous again from there to the Elderslee fault, 

 and then Upper Coal-Measures at Westbrook Creek. The fact 

 that all these different series are cut off on their northern side, in a 

 fairly regular line, favours the existence of a fault. 



(b) Where the Permo-Carboniferous rocks approach close to the 

 Webber's Creek Series (at One-Tree Hill), they have very high dips 

 to the south, while a short distance to the west, where they are not 

 so close, the dip is much less. 



(c)Also where the Permo-Carboniferous shales are nearest the 

 Webber's Creek Series, there is a slight amount of metamorphism 

 of the shales, which might easily have been the result of faulting. 



(d)No tuffaceous sandstones, similar to the Webber's Creek 

 Series, are found associated with the Carboniferous rocks, south 

 of the line of junction of that series with the other series. 



The Webber's Creek Series seems to be of the same age as 

 similar rocks near Clarencetown, which Jaquet* has determined as 

 Upper Carboniferous. The throw of the Webber's Creek fault is 

 about equal to the amount of strata between these rocks and the 

 top of the Carboniferous strata, but, as the exact position of these 

 rocks in the Upper Carboniferous has not been determined, it is not 

 possible, at present, to say what is the amount of the throw of this 

 fault. 



* Op. cit., p. 62, 



