Geology 



surface had become cooler and there was no appearance 

 of molten matter. That there was still liquid within 

 was indicated by the steady onward movement of the 

 great mass of slag and the grinding, tearing noises which 

 constantly came from within. 



Climbing a slight eminence, a remnant of an ancient 

 lava-flow, we were able to get a clear view of the front of 

 the stream, where it was advancing towards the lake. 

 The ground in front was covered with grass and reeds, 

 and lumps of slag were continually rolling down from 

 the top of the heap on to the vegetation. 



The upper part of the stream seemed to be slowly 

 pushed forward so that the end face became more steep, 

 then masses would detach themselves from the top and 

 roll down, thus restoring the original angle, and this was 

 repeated again and again. 



Steam was continually escaping from the crevices 

 between the blocks of slag, and here and there a dull red 

 glow could be seen in some of the deeper cavities. The 

 edge of the swamp surrounding the lake had now been 

 reached, and the fact that the slag, though solid, was still 

 hot, was demonstrated as each fresh mass rolled down 

 into the swamp, when clouds of steam were produced. 



As the advancing front sank into the soft ground, 

 the progress of the stream seemed to be temporarily 

 arrested, and the face became steeper and higher than 

 hitherto. So entranced had we been watching the slow, 

 steady, irresistible advance of the stream that it was 

 only now that we realized that this arrest of the move- 

 ment foreshadowed a catastrophe, and it was well for us 

 that we left the summit of the mound and made our way 

 some distance up the slope of the large cone to a point 



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