Geology 



it was level for some 20 yards, and then rose 

 rapidly, at the same time narrowing rather abruptly. 

 There was found to be a gentle current of air from below 

 which passed on into this upper and narrower part of 

 the cave. 



On obtaining an armful of dry grass from outside 

 and setting fire to it, we found that the smoke was 

 carried away up the passage, and that in consequence 

 we could light a fire without fear of suffocation. 



Here, then, was an ideal shelter for the night, and 

 we at once set to work to collect our belongings from 

 the valley and to transport them to our new home, in 

 the meantime setting the men to collect and bring up 

 all the fuel they could find. 



Scarcely were our preparations complete, when the 

 storm burst upon us, and we were glad to retreat to 

 our cavern. Lighting a fire, we were able to cook 

 supper and arrange our sleeping bags for the night, 

 and as we owed its discovery to him, the Troglodyte 

 was put in charge. Before turning in for the night 

 one of the party climbed down to the entrance and 

 reported that the storm was over, only distant rumblings 

 of thunder and occasional flashes of sheet-lightning 

 now remaining. 



Even at the very height of the storm the thunder 

 could only be heard in the cave with difficulty, owing, 

 we supposed, to the narrowness of the entrance. We 

 were therefore much surprised to be awakened just 

 after midnight by a loud rumbling which rapidly in- 

 creased to a continuous roar, while the air in the cavern 

 appeared to vibrate so that we could not tell whence 

 the noises came. 



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