The Underground Drainage 



Under these circumstances we decided to postpone our 

 departure for Lyell, although camp life had become 

 decidedly unpleasant. 



It was noticed that Blind Burn was now occupied 

 by a stream, and as we hoped to prove a connection 

 between this and the cave where we had sheltered 

 from the thunderstorm on our first visit to the pla- 

 teau, we once more climbed the escarpment armed 

 with fluorescein. 



We found the stream overflowing the Lake Sink and 

 once more falling over the cliff near Thunder Cave. At 

 the foot of the fall we introduced the fluorescein, and 

 were able to trace it a few minutes later in the abyss of 

 Thunder Cave, and within twelve hours it was seen in 

 Blind Beck. 



While on the plateau observations were made as to 

 the direction of the joints in the limestone, and of these 

 there were found to be two sets. One of these by far 

 the most persistent and well-marked lay N. 10 E. to 

 S. 10 W., the direction of the flow of the underground 

 drainage, while the other and weaker set was approxi- 

 mately at right angles to this. 



From these observations it was clear that the direction 

 of flow of the underground waters was controlled by the 

 direction of the master joints in the limestone, a con- 

 clusion which had previously been arrived at in other 

 parts of the world. 



At the end of the week, the storm having somewhat 

 abated, we were able to set out for Lyell, and after some 

 little trouble on account of the swollen state of the rivers, 

 were able to return to our warm cabins on the steamer, 

 and to the luxury of dry clothes. 



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