142 E. 0. Teale: 



an acid alkali province, in contrast to the acid sub-alkali 

 province to which the dacites and grano-diorites belong, 

 but conforming to a normal variation curve. 

 ■3. Under the heading of Palaeozoic Earth History, the following 

 '.featuresi are discussed : — 



(1) Successive distribution of Land and Water. 



(2) Types of Earth Movements. 



,(3) Granite Batholiths and their Relation to Palaeozoic Struc- 

 ture. 



(4) Pitch along Anticlinal Lines. 



(5) Relation' of Dyke Rocks and Quartz Reefs to general struc- 



ture and Eartli Movements. 



(6) The Fractui-e line of tlie " Snowy River Porphyries." 



A succession of Palaeozoic basins of sedimentation, with a gene- 

 ral northerly trend appears to be recognisable.' These have varied 

 in position and extent from period to period. 



They have overlapped in certain instances, while in others they 

 appeal' to have been laterally shifted, a land area taking the place 

 ■of the basin of an earlier period, and vices versa. 



The resultant formations have nevertlieless a general parallel 

 arrangement. 



This succession of basins, jiaralU'l, but laterally shifted or re- 

 stricted, is thought to be best explained by the conception of a slow 

 wave-like undulation of the earth's crust, the basins being the 

 reciprocal feature of the adjacent land mass. The basin would, 

 therefore, be regarded as of the type of a geo-syncline. Block 

 movement, though not excluded entirely, is regarded of minor im- 

 portance during this era. The most intense folding was pre- 

 Devonian. The great granite batholiths, though belonging to the 

 active Devonian period of tectonic and igneous disturbances, show 

 much irregularity of shape and distribution, and also a discordance 

 with strike and fold lines. It is considered tliat their features 

 generally are best explained by the conception of " magmatic 

 'Stopmg." 



The consequent disturbance; of surrounding and over-lying blocks 

 of sediments may have been one of the most important agencies in- 

 ducing the features of " pitch,"' so coiimion throughout the Lower 

 Palaeozoic formations. Certain zones appear to have been subjected 

 more frequently during Palaeozoic times to tectonic and volcanic 

 disturbance than other regions. 



The Wellington-Mansfield Belt is one of these areas, the zone of 

 the Snowy River Porphyries represent-s another. 



