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The National Geographic Magazine 



once filled the old canyon completely. 

 The Little and Big Zigzag canyons are 

 cut in it. The Little Zigzag has not 

 reached bottom ; the Big Zigzag at its 

 upper forks is in about 30 feet of basalt, 

 but a little farther down stream it is still 

 trenching in the drift. The south fork 

 of the Sandy and Slide Creek are begin- 

 ning the herculean task of cutting away 

 the drift that nearly fills the old canyon 

 that lay between Slide Mountain and 

 Paradise Park on the south and Yocum 

 Ridge on the north. 



To account for this enormous mass of 

 debris, there is this possible explanation: 

 The forces that built the mountain left it 

 with a well-developed summit crater 

 about one-half mile in diameter and 500 

 to 700 feet deep, with the lip at the south- 

 west side somewhat lower and probably 

 of less resistant rock than that on the 

 north side. When the age of ice came 

 on, this crater became filled with snow 

 and the mountain was covered with an 

 ice-cap such as we now see on Rainier 

 and Adams. Glaciers formed on the 

 sides and gradually worked back until 

 the whole southern rim of the crater was 

 cut away and the materials that made it 

 were spread out on the lower slopes and 

 filled the canyons that had previously 

 been trenched. The glaciers then ex- 

 tended back to the inside of the north 

 rim as they still do. They cut away the 

 floor of the crater, but the harder rock of 

 the old neck resisted and divided them 

 and survives as Crater Rock. 



The other sides of the mountain have 

 also been trenched more or less deeply 

 and much debris is spread out below, but 

 nowhere in such quantities as on the 

 southwest. 



ABUNDANT FOSSIL ICE STILL FOUND 



Let us now examine the White River 

 Canyon more in detail. Unfortunately 

 the map has not been extended enough 

 to the south to shed light on the nature 

 of this canyon below its immediate rela- 

 tion to the mountain. There seems, 

 however, but little question that when the 

 ice filled the Zigzag and Sandy valleys a 



similar glacier extended many miles 

 down the White River. This glacier was 

 deeply covered with debris from the 

 ruined crater. So thick was this debris 

 and so well protected by it was the ice 

 that to this day some of the ice of the 

 ancient glacier remains. In the section 

 exposed by the cutting of the new 

 streams, fossil ice to the depth of 10 to 

 15 feet may be seen at the bottom of the 

 small ridge which Reid has called Mo- 

 raine Mesa. The section of Moraine 

 Mesa exposed is shown in the accom- 

 panying sketch. 



The bottom layer is the fossil ice. This 

 is covered with from 75 to 150 feet of 

 morainal material. Above this is about 

 three feet of black soil, or forest humus y 

 on which rests or is rooted a confused 

 mass of tangled logs, with an occasional 

 stump standing erect. Some of these logs 

 are above two feet in diameter. They 

 are still wood in a good state of preserva- 

 tion, being neither carbonized nor silici- 

 fied. The top layer is drift again of the 

 same character as the lower layer and is 

 from 10 to 75 feet thick. It indicates, of 

 course, a return of frigid weather condi- 

 tions and a readvance of the ice after a 

 temperate climate period long enough, at 

 least, to allow for the growth of the over- 

 thrown artd buried forest. 



This "second drift sheet extends only 

 from the' forks of the smaller canyons at 

 the head of the present valley back to the 

 end of the existing glacier or possibly 

 beneath it. It is too recent for vegeta- 

 tion to have made headway upon it. One 

 or two small pines and a few grasses 

 and bipines are all that it has. A few 

 buried logs were observed on the west 

 side of the mountain, near the end of one 

 of the prongs of the Zigzag Glacier, 

 which indicates a probably similar re- 

 advance of the ice on that side. 



It is scarcely necessary to speak here 

 of the glaciers as there are today. The 

 map speaks for itself in regard to them. 

 The Survey last year, for the first time 

 in its history, adopted the method of con- 

 touring the glaciers, the contour lines on 

 them to be shown in light blue. There 



