]}Y H. I. JENSEN. 579 



beds, the cone is being destroyed, all but the central plug. In 

 -the same way have most of the steep-sided monoliths been formed. 



5. Springs and Artesian Water. 



(a) Springs. — The fact that powerful springs with a perennial 

 flow often occur on the summits of the highest mountains and 

 very seldom in the valleys, has been the cause of much astonish- 

 ment and speculation. I have heard the problem discussed by 

 men of every occupation, from tramp to squatter, and from 

 stockman to doctor. 



Near the summit of Mount Terra Terra, at an altitude of 

 3,500 feet, I saw a powerful spring, which, during the drought, 

 gave a permanent flow of water, and was the saving of much 

 stock. Near the summit of Tenandra Gap two great springs 

 originate at an altitude of more than 2,500 feet, and feed the 

 heads of Wombalong and Belar Creeks. Below Siding Spring 

 Mountain, on the south side at an altitude of about 3,000 feet, 

 is the large and permanent Siding Spring; and on the northern 

 side of the same mountain, at the same altitude, is another great 

 spring, the Boonoo Spring I believe they call it. Then we have 

 Wheoh Springs, Yarragrin Springs, Bulleamble Springs, and 

 many others in the Warrumbungles. 



Springs at the bases of mountains may be due to meteoric 

 waters which have accumulated in wet seasons, and which escape 

 gradually. Such springs would, however, not be permanent. 

 They would weaken appreciably in a prolonged drought, and 

 would show an inoeased flow in wet seasons. The Warrum- 

 bungle Springs, according to information received from numerous 

 local station-owners and stockmen, show an increased flow in 

 drought times, and a diminished one in wet seasons; but they 

 never disappear entirely except to reappear close by. The waters 

 are, therefore, of deep-seated origin. 



The causes advanced in text-books to account for springs are 

 (1) steam-pressure, (2) gas-pressure, (3) hydrostatic pressure, 

 (4) pressure of overlying rocks. 



