Geology 



as there was no sign of a landing on either side, and the 

 water was extremely cold, he was compelled to return. 



The water in the cave was still and deep, being held 

 up by a natural weir made up of an accumulation of 

 boulders just outside the entrance. It was clear that 

 for any further exploration we should require a light 

 canoe, and as there was every sign of the cave penetrat- 

 ing far into the mountain, we decided to send two of our 

 men down to Lyell to procure one, and also a supply of 

 ropes and, if possible, rope-ladders, as these might be 

 required if much underground exploration was to be 

 carried out. A large supply of tallow candles, some 

 magnesium powder for underground photography, and 

 two iron drums containing a powerful colouring matter 

 called fluorescein, which we had brought out with us from 

 home, might also be required. 



Having returned to the light of day and partaken 

 of our midday meal, we next turned our attention to 

 determining the relationship between the massive lime- 

 stone of the cliff and the " Millstone Grit " lower down- 

 stream. 



Following the course of the river, we found several 

 exposures of the limestone with a dip of from 2 to 5 to 

 the north-east. From this it would at first sight appear 

 that the limestone was newer than and resting upon the 

 grit, but when we remembered that only some few miles 

 down-stream the grit was dipping in the opposite direc- 

 tion, and passed conformably below the Coal Measures, 

 there was clearly no room for the massive limestone, 

 which must be at least 500 feet in thickness, in the series. 

 On following the stream still farther in a downward 

 direction, we found several reefs of grit dipping at a high 



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