BY LEO A. COTTOX. 497 



reached fi'om t!ie latter town either by the Inverell-Copeton 

 Road, or by a turn-ofF from the Inverell-Bundara Road. The 

 country in the immediate vicinity of Howell pi-esents some very 

 interesting physiographic features. The New England Plateau 

 is here worn to the level of the Stannifer* peneplain, above 

 which residuals of an older peneplain about 400 feet higher are 

 visible. This plateau is intersected by the Gwydir River, of 

 which Borah Creek is a tributary. 



The country-rock is one of the " acid granites, "f and is of a 

 reddish colour on account of the abundant pink orthoclase 

 crystals present. Comparatively large areas, several acres in 

 extent, of smooth bare granite relieve the forest-greens by their 

 brick-red colour. Tiiis is specially noticeable on the northern 

 sloj^es of the hill facing the town. The Borah Creek Lode has 

 proved of less hardness than the " acid granite," and its con- 

 sequent more rapid rate of erosion has determined the position 

 of the creek, wliich follows the outcrop in a most marked manner 

 (see text-fig. 1). The lode has been intersected by one con- 

 spicuous fault which has thrown it, and has also left its mark 

 upon the topography. Where the fault crosses the lode in 

 Borah Creek, a small tributary is developed on each side along 

 the line of the fault-plane (see text-tigs. 1-2). 



Geology. 



The geological formations of the district consist of three units, 

 slates, granites, and basalts. 



The slates are the oldest series, and are probably of Silurian 

 age. They are everywhere much altered by the intrusions of the 

 later granites. The nearest occurrence of these rocks to the mine 

 is a comparatively small patch, situated about 2 miles to the 

 north by east from Howell. 



* Andrews, E. C, "The Geology of the New England Plateau. Part i.» 

 Physiography." Records Geol. Survey N.S.Wales, Vol.vii., pp.2Sl, 1904. 



f Ibid., Parts ii. and iii., with special reference to the granites of Northern 

 New England. .,''fCT7»~S'"*?s^ 



Li t i B R A R Y 

 V^ -^^"^ 



