250 



J. C. Branner — jEolian Sandstones of 



rocks in many places about the island, all of which is cemented 

 by carbonate of lime. For the most part it is very porous, 

 and the cavities are seen to be gradually filling up by the building 

 into them of crystals of carbonate of lime. No quartz has 

 been found in any of the specimens examined microscopically. 

 On Ilha Kaza the bedding of this rock is beautifully exposed 

 in a perpendicular bluff 40 feet or more in height, at whose 

 base lie the enormous fragments that have fallen by their own 

 weight after having been undermined by the ocean (see fig. 4). 



4. 



Cliff and fallen blocks of sandstone, Ilha Raza. 



The wind-made bedding of the material is well shown in many 

 parts of this exposure. 



On the southeastern corner of Ilha Rapta sandstone caps the 

 igneous rock, and rises to a height of 50 feet or more above 

 the water (see fig. 5). Here is situated the great "blow- 

 hole," shown in fig. 8 and described at the end of this paper, 

 where the waves of the ocean operating through hidden 

 passages in the rocks near the mean tide line forces a powerful 

 jet of spray through a narrow opening to a height of more than 

 a hundred feet, and the prevailing winds carry it east and 

 north over the island. The water from this spray has attacked 

 the sandstone, leaving it with a deeply etched surface, the more 

 resisting points, from one to three feet high, being so jagged 



