Photograph by R. F. Griggs 

 AN ASH-COVERED SNOW BRTDGE SPANNING A STREAM WHICH CUT ITS WAY THROUGH 



BENEATH 



The caving in of such bridges, which are often concealed, constitutes one of the most serious 

 dangers to which the explorer is subject 



place which looked safer. Then we ap- 

 proached the edge. Nothing could be 

 seen through the rising steam. 



But, as we looked, there came a little 

 rift and we could see something blue far 

 below us. Then the steam cut us off 

 again and we waited. Again it blew 

 away and we were struck speechless by 

 the scene, for the whole crater lay below 

 us. It was of immense size and seemed 

 of an infinite depth. 



A VITREOUC LAKE 



About half of the bottom was occu- 

 pied by a wonderful blue and green vit- 

 reolic lake, with the crescent-shaped re- 

 mains of an ash cone near the middle. 

 In the larger end was a circle of lighter- 

 colored water which was in continual 

 ebullition. 



Around the margin were a thousand 

 jets of steam of all sizes, issuing from 

 every crevice with a roar like a great 

 locomotive when the safety valve lets go. 

 On the far side, close to the water, were 

 two large, bright yellow spots of sulphur, 

 while in two angles of less activity there 

 were snow-fields. 



The perpendicular >ides near us were 

 composed entirely of frozen mud and 

 fragments of various sorts of ejecta, and 



nowhere in the whole ascent did we en- 

 counter bedrock. On the opposite side 

 of the crater we could see that the greater 

 part of the wall was composed of lava 

 and tufa, the successive flows giving it a 

 roughly stratified appearance. 



"We were powerless to form any real 

 estimate of the size of this stupendous 

 hole. It was clear, however, that it oc- 

 cupied all of the area within the rim, 

 which from below appears three miles 

 long. As to the depth, the best I could 

 do was to look in and then try to carry 

 the same level to the slope up which we 

 had come. Thus estimated, the depth 

 was apparently about 1,500 feet. This 

 estimate we subsequently had to enlarge. 



All this we took in almost at a glance. 

 Before we could get our tripod set up 

 the cloud closed in again and w T e waited 

 amid a thunderous roar of escaping 

 steam. V\'ere we to be cheated of the 

 coveted pictures after all? Finally the 

 cloud lifted a little and frantically we 

 made our exposures. 



I had planned to take bearings and 

 measurements which would permit more 

 accurate determination of the depth and 

 size, but we were vouchsafed so few 

 clear moments that we could not make 



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