:X1V PRESIDENTL\1, ADDRESS. 



covered by basalt. Often very rich in stream tin. Sometimes 

 gold-bearing. 



Age. — Probably but little older than the basalt. Pliocene. 



(4.) (Tranitc awl Dioritc Masses, Poriihi/r;/ Masses and Di/kes, 

 FArans and other Dijhci, Intrufiiee Eclor/ijte and allied lioclt. — Of 

 "these igneous rocks the granite masses are the oldest, and are 

 generally intimately associated with the porphyry masses, and 

 porphyry dykes. The other rocks are for the most part newer 

 than the granite and porphyry, but almost invariably associated 

 with them. These are yv/ /• e.rellence the mineral-bearing rocks. 

 All are newer than the Chillagoe Limestone. 



Age. — Upper and Fjurer Pennia)i, 



(5.) (.'/lillai/oe Limestone. — Beds of more or less crystalline 

 limestone, lying in a synclinal trough, \xnconformable to the 

 Herberton Beds. Much denuded, full of caves, and probably 

 originally about 400 feet in thickness. Contains obscure crinoids, 

 corals, polyzoa, brachiopods, &c. Much altered in places by contact 

 with and intrusions of granite-masses and dykes of eclogyte, 

 when it becomes ore-bearing, the ores hAng copper, lead and 

 silver, but not gold or tin. The ore is seldom in the limestone 

 itself, but confined to the intrusive eclogyte. (Rarely, old cave- 

 deposits carry rich copper ore.) 



Age. — Lower Permian or Upper ('arJioniferous. 



(6.) Montalhion Beds. — A series of comparatively unaltered 

 shales and sandstones, with calcareous seams and bands of 

 nodular clay-ironstone. Often lying at low angles. Separated 

 provisionally from the Herberton rocks, on which they lie, in 

 consequence of their marked lithological peculiarities, and un- 

 altered character. Only seen around Moutalbion Hill. Contains 

 silver-lead, copper and fahl-ore in lodes and mineralised beds. 



Age. — Loirer ( 'arhoniferous. 



(7.) Herberton Beds. — A great series of arenaceous and 

 argillaceous rocks, ranging from coarse conglomerates (the 

 Ringrose Conglomerate) to fine sandstone and quartzite : 

 greywacke, slate and mica-schist ; with occasional beds of 

 limestone, which have been mistaken for Chillagoe Limestone. 

 Continuous right across the area, narrowing towards Chillagoe, 



