MOUNT RAINIER 



walls of Gibraltar. This massive pile is largely made 

 up of boulders, great and small, rather loosely held to- 

 gether by a lava cement. The work of frost and ice, 

 expansion and contraction, loosens the boulders readily, 

 and their constant falling from the cliffs gives to this 

 part of the mountain's ascent its dangerous character. 

 While this volcano belongs to a very late period in the 

 history of the earth, it is very clear that there has been 

 no marked activity for many thousands of years. The 

 presence of steam, which is emitted from the hundreds 

 of small openings about the crater, undoubtedly shows 

 the presence of heated rock at no great distance below 

 the surface. Rock is a poor conductor, however, and 

 cooling takes place with very great slowness after a 

 depth of comparatively few feet is reached. 



Like most volcanoes, the composite character of the 

 cone is shown on Mount Rainier. After a certain 

 height is reached in the building up of a cone, the rising 

 lava in the throat, or the explosive activities within, 

 sometimes produce an opening through the walls of 

 the cone, and a new outlet to the surface is formed. 

 This often gives the volcano a sort of hummocky or 

 warty appearance, and produces a departure from the 

 symmetrical character. In the case of Rainier it seems 

 to the writer that upon the summit four distinct craters, 

 or outlets, are distinguishable. The first crater reached 

 by the usual route of ascent is the largest one, and may 

 be styled the East crater. It is nearly circular in 

 outline, with a diameter of about one-half mile. Its 

 walls are bare of snow for nearly the whole of its cir- 

 cumference, but the pit is filled with snow and ice. 

 Going across the crater to the westward, one passes 

 over what is really the highest point on the mountain, 

 and then goes down into a smaller crater, or the West 

 crater. This is similar in character and outline to its 

 neighbor, but here the many jets of issuing steam are 

 much more prominent. At a point a few hundred 

 feet lower on the mountain-side there is a peak known 



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