140 E, 0. Teale: 



(3) Denudation of the existing cycle has developed to such an^ 



extent that a complex inlier is exposed, consisting of 

 a core of Cambrian rocks enveloped successively by 

 Upper Ordovician, Silurian and Upper Palaeozoic sedi- 

 ments. 



(4) The Upper Palaeozoic strata are of lacustrine origin, and 



those of the other periods are marine. The Cambrian 

 limestones have yfelded a definite series of trilobites, and 

 are interbedded in basic tuffs. The Upper Ordovician 

 rocks are black slates, chertified in part, and they con- 

 tain abundant typical graptolites. The Silurian rocks 

 have so far only yielded crinoid remains. 



(5) Igneous activity is represented in two and probably three, 



distinct periods if Ave consider the district as a whole, in- 

 cluding the Upper Palaeozoic rocks as far as Mansfield. 

 The Cambrian series contains a pre-Upper Cambrian ser- 

 pentine, with chromite and corundum derived from peri-' 

 dotite and pyroxenite rocks, and the Upper Cambrian 

 contains basic tuffs. Volcanic rocks of the nature of por- 

 phyrites allied to dacites occur in the King River Valley, 

 and others, mainly of an andesitic nature, on Fullarton's- 

 Spur, in the Macallister Valley. These are probably 

 Lower Devonian. The basal portions of the Upper 

 Palaeozoic (Lower Carboniferous), contain thick beds of 

 rhyolite, and acid pyroclastic deposits. Higher up in 

 the series there is a succession of basaltic flows (mela- 

 phyres) interbedded with the sediments. 



(6) Special structural features are noted along the Macallister 



valley, where the Upper Palaeozoic rocks, normally dip- 

 ping at a low angle, are here frequently highly inclined, 

 and an important fault line is recognised, approximating 

 in position to that of the Macallister Valley, -and bear- 

 ing, therefore, in a N.N.W. direction. 

 2. 2'he District of Nova Nona. 



(1) The cherts and jaspers of the region have been examined' 

 with regard to age and the origin. All the cherts ob- 

 served are altered slates, and are regarded as Upper 

 Ordovician. Definite graptolites have been found in 

 some of them. The red jaspers are often associated 

 with micaceous hematite, and are found chiefly in the 

 porphyroid belt of the " Snowy River Series," and are- 



