BY H. I. JENSEN. 581 



This accelerates decomposition, hence increases gas-pressure, and 

 produces a strong flow from deep-seated sources. This flow is 

 the more powerful from the fact that the widening of joint- 

 cracks and fissures has lessened resistance. 



In 1902, springs were particularly active in this region. 

 Personally I am inclined to believe that even the cause suggested 

 above is inadequate to explain this, and that there was, as well, 

 a great cosmic cause at Avork, the same which produced the 

 violent volcanic activity in other parts of the world. Perhaps 

 some such cause was, during the drought, causing slight folding; 

 and hence increased rock-pressure in these parts. 



It is interesting to note that in 1902, when the Namoi had 

 become a series of waterholes, powerful springs broke out in the 

 bed of the river in several places, causing it to flow for miles. 

 In the same year remarkable cracks, big enough to swallow a 

 cart, opened near Trangie, not far from Dubbo, quite suddenly, 

 without any shocks of earthquake being felt, and gradually closed 

 up again. These were in the Black Soil Plains, and may there- 

 fore have been due to desiccation; but I am informed that the 

 occurrence was sudden. May it not have been caused by an 

 earth-movement not of suflicient violence to produce appreciable 

 shocks at a distance, and not felt locally on account of the thick 

 blanket of loose soils on the plains (cp. the cracks formed in the 

 Cachar Earthquake; see Suess, ' La Face de la Terre,' Ch. i.)? 



(b) Artesian Water. — The following facts have been elicited by 

 conversation with local inhabitants and by personal observation: 



(1) Most of the Warrumbungle streams flow perennially in the 

 mountains, but cease to flow on reaching the plains. 



(2) They are supplied by springs at an altitude of from 2,500 

 to 3,000 feet or more. 



(3) They cease to flow at an altitude of about 1,000 to 1,500 

 west and north of the Warrum bungles. 



(4) Many continue to flow at a depth in the sand in their beds, 

 or in billabongs filled with sand, for some distance, but more 



