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WALLACE W. ATWOOD 



horizons. In general, the contributions of angular blocks were greater 

 during the later than during the earlier eruptions. At times true 

 volcanic bombs were thrown out, which indicate that molten lava 

 must have risen well 'up into the crater. 



The lava which issued near the close of the period of growth over- 

 flowed to the southwest and descended but part way down the slope. 



Fig. 5. — Looking west in Red Mountain. The layers of tuff come out clearly 

 near the base, but are obscured on the upper portions of the slope by the general 

 pitted condition of the surface. The pits are where great masses of lava have 

 been weathered out. 



The southwest portion of the crater rim was presumably lower most 

 of the time, for the prevailing winds from that direction must have 

 carried a large proportion of the ejected material to the northeast 

 side. 



The erosion. — Rain and running water have removed all traces of 

 the crater, and the present summit is but a narrow crescentic ridge 

 dividing the waters which operate on the southwest and northeast 

 slopes. The erosion on the southwest side has been referred to 

 with sufficient detail. On the northeast the mountain may be 



