50 



Z. F. Harjper — Evidence of Uplift. 



ranean roar is accompanied by a tremor in the roof of the 

 cavern and is followed by a jet of spray shot from 50 to 100 

 feet into the air. (Fig. 3.) 



Caves and channels now 16 feet above high-water mark and 

 similar in appearance to the blowholes described indicate a 

 similar origin. As blowholes are necessarily formed at sea- 

 level, the conclusion to be drawn is that the coast has been 



Fig. 2. 



Fig. 2. Entrance to tunnel leading to blowliole. Kainia, New Sonth 

 Wales. 



raised. Caves developed along dike channels extend under 

 cliffs for distances ranoino^ from a few feet to 200 feet. The 

 dike material at the end and in the roof of these caves is from 

 2 to 4 feet wide, but caving of the walls has enlarged the 

 openings and produced caverns from 6 to 30 feet wide. The 

 largest of these caves — Hole-in-Wall — (formed in sediments of 

 the ]S"arrabeen stage, Triassic) is about 10 miles north of Syd- 

 ne}^ The floor of this cave is strewn Avith sand and sandstone 

 blocks accumulated long after it was elevated above the sea ; 

 and the present floor level does not, therefore, indicate the 

 amount of uplift. Caves in Permo-Carboniferous strata about 



1 



