1872.] DAINTEEE GEOLOGY OE aUEENSLAND. 273 



I collected the following- data whilst prosecuting the search for 

 new gold-fields, on behalf of the Queensland Government, in the 

 northern portion of their territory, as also from the official reports of 

 the Geologist of Southern Queensland, and other trustworthy sources. 



The consideration and history of the difi^erent formations will be 

 taken in their sequence of time, as far as the stratified or sedimen- 

 tary rocks are concerned. The igneous rocks will be described under 

 the various groups of Granitic, Trappean, and Volcanic. 



Aqueous. 



Alluvial, recent. 



Alluvial, containing extinct faunas. 



Desert Sandstone. Cainozoic. 



Cretaceous. 1 



Oolitic. \ Mesozoic. 



Carbonaceous. J 



Carboniferous. 1 



Devonian. \ PalcBozoic. 



Silurian ? J 



Metamokphic. 



Allitvial. 



Fluviatile or freshwater deposits skirt all the present water- 

 courses ; but the accumulations are insignificant on the eastern water- 

 shed, except near the embouchures of large rivers, such as the 

 Burdekin, Fitzroy, &c. 



On the shores of Carpentaria, however, and in the south-ivestern 

 portions of the Colony, where the water-courses have scarcely any 

 fall, and where in seasons of excessive rain the country is nearly all 

 inundated, fluviatile deposits are very extensive. 



Although the sediments redeposited as alluvia between the main 

 dividing range and the east coast are, as stated, comparatively 

 insignificant, they represent the denudation of no insignificant amount 

 of varied rock material, since the present physical contour of the 

 eastern portion of the Colony is probably due to the influence of 

 meteoric action, such as rain &c. 



Though the dense lavas of the Upper Burdekin (volcanic outbursts 

 of a late Tertiary epoch) are traversed by valleys of erosion, in some 

 cases 200 feet deep and 5 miles broad, yet very narrow and shallow 

 alluvial deposits skirt the immediate margin of the water-courses 

 draining such valleys. 



The same conditions are met with in all the more elevated table- 

 lands or ridges which give character to the present physical outline 

 of the eastern main range. 



It is only near the mouths of the larger rivers that any extent of 

 alluvium has been deposited ; and even these areas are at the present 

 time in seasons of excessive rain liable to inundation, showing that 

 little upheaval of this portion of Australia has taken place since the 

 last volcanic disturbances terminated. 



The meteoric or climatal conditions during this period were nearly 

 identical with those of the present time, heavy rains during the 

 summer months causing violent floods, removing seaward the aerial 

 decompositions and denuded materials from year to j'ear. 



