BY H. I. JENSEN, D.SC. 168 



Another point of interest in this connectio;n is the 

 fact that artesian water, which occurs in Queensland only 

 in rocks of late Mesozoic age, has been obtained in 

 Western Australia in rocks of Permian, Carboniferous, 

 and even older ages. This shows still more forcibly 

 that since the early Palaeozoic, Western Australia has 

 been a unit or block of the earth's crust in which no 

 compression of strata has occurred, and in which the 

 only earth movements (faults and fractures) have been 

 the result of tangential strain. 



In 'Bull. 33, Geol. Surv. of W.A., Mr. A. Gibb- 

 Maitland [2] shows that at Pelican Hill artesian water 

 was obtained at a depth of about 3,000 feet in the lowest 

 bed of the Carbo^niferous series, a sandstone stratum 

 about 448 feet thick. In the Collie Coalfield mining 

 is greatly handicapped by the constant soakage of 

 artesian water into the workings. 



In the Irwin Coalfield (Bull. 38, Geol. Surv. of W.A.), 

 the coal is hydrous, and the carboniferous rocks are 

 water bearing. [3] 



Clearly, from this the post- Cambrian rocks of the 

 Western Australian block are porous by virtue of being 

 uncompressed, and in many cases they are in a state 

 of strain or tension. We may therefore conclude 

 that West Australia has been a relatively rising mass 

 from the beginning of the Cambrian. 



In Eastern Australia, all rocks of pre-Triassic age 

 have undergone such compression that their original 

 water content has been expelled, and they have become 

 too impervious to take up water again. 



Cambrian Sedimentation. 



Examination of the Cambrian areas of sedimenta- 

 tion shows {Fig. 2) us that they are all situated to the 

 east of the main Pre- Cambrian massive, already referred 

 to. They lie on a definite band about 300 miles wide, 

 running in a crude north-westerly direction from 

 Tasmania to Kimberley, in W.A. This band then 

 corresponds to the Cambrian area of intense sedimenta- 

 tion, including the continental shelf of the period. 



The chief localities for Cambrian rocks are the 

 Caroline Creek district in Tasmania ; the Heathcote 



