Our Noblest Volcano 



517 



twelve years, and having come under its 

 spell, it was with pleasure that I received 

 my orders from the U. S. Geological 

 Survey, in the spring of 1907, to begin 

 the mapping of the Mount Hood Special 

 Quadrangle. 



The latitude of the mountain is 45 ° 

 22' 26". 74; its longitude, 121 ° 41' 42". 8r 

 west of Greenwich. It lies on the crest 

 of the Cascade Range, about 20 miles 

 south of the Columbia River and 50 

 miles east of the city of Portland. It is 

 the highest point in the State of Oregon, 

 rising to a height of 11,225 feet - This 

 elevation was determined by Col. R. S. 

 Williamson, U. S. Army engineers, at an 

 early date, and was checked by me last 

 summer. 



Timber grows on and about the moun- 

 tain up to an elevation of 6,500 feet. 

 The highest trees are stunted hemlock 

 and dwarf pines, which venture out from 

 the denser forest along the straggling 

 lines of the old moraines. 



The waters of Mount Hood reach the 

 Columbia mainly through the Hood and 

 Sandy rivers and their tributaries. Hood 

 River drains the northern and eastern 

 sides; the Sandy, the southern and west- 

 ern. White River, which receives the 

 drainage from one glacier on the south 

 side, is a tributary of the Deschutes, 

 which reaches the Columbia above the 

 Dalles. At low water the flow of these 

 streams, according to the measurements 

 of the Hydrographic Branch of the Sur- 

 vey, amounts to about 750 second- feet — 

 enough water to cover in a year the Dis- 

 trict of Columbia about 160 feet deep ! 



AN ALMOST PERFECT VOLCANIC CONE 



Mount Hood is one of the great vol- 

 canic cones built upon the Cascade pene- 

 plain in Miocene times. It is the fourth 

 in height of the snow peaks of the Pacific 

 Northwest, being surpassed only by 

 Rainier, Shasta, and Adams. The pene- 

 plain-like plateau upon which it stands 

 is now well dissected, but the numerous 

 remnants show a fairly uniform eleva- 

 tion of from 4,000 to 4,500 feet. The 

 mountain rises, therefore, about 7,000 

 feet above the surrounding countrv. It 



was probably never much higher than at 

 present. 



Though showing many of the features 

 of the volcanic cones of the region, it has 

 enough peculiar to itself to give it a 

 marked individuality. With the excep- 

 tions of Saint Helens, in Washington, 

 and Pitt, in southern Oregon, its cone is 

 more nearly perfect than the others. It 

 appears to have been built up entirely of 

 andesitic lavas which were ejected from 

 a single summit crater. Unlike Adams, 

 it has no subsiding craters or smaller 

 blow holes on it or about its base — at 

 least none of recent age. Barrett Spur, 

 Langille Crags, or Coopers Spur may 

 have been such craters ; but, if so, they 

 are very old and have weathered to such 

 a degree that they no longer have a 

 crater-like appearance. 



The volcano apparently became ex- 

 tinct before reaching the stage of the 

 ejectment of the more basic basalts which 

 Shasta and Adams poured out in com- 

 paratively recent times. In this connec- 

 tion, however, it might be well to state 

 that there is, some ten miles to the north- 

 east, a large lava flow, probably from 

 fissure, that from a distance appears re- 

 cent. It was not visited, but could be 

 seen fairly well with field glasses, and at 

 the distance resembled lava flows that 

 lie on the north and south sides of Mount 

 Adams and could probably be correlated 

 in time with them. Neither timber nor 

 grass has as yet begun to grow upon it. 

 The rock of which the mountain is 

 built is greatly seamed and fissured. 

 Water penetrates it easily, therefore, and, 

 freezing, shatters great masses. On the 

 lower slopes one sees all stages of such 

 disintegration. There are boulders as 

 large as a house shivered into a thousand 

 pieces by frost. Some of them retain 

 their original shapes, others are falling 

 down, and yet others are but a pile of 

 earth. 



GOUGING BY GLACIERS 



In the work of tearing down the moun- 

 tain, ice has indeed played the star part. 

 While the freezing of water into the 

 joints has fractured the rock, the glaciers 



