GO.AIPOSITION AND STRUCTURE OF GLACIAL DEPOSITS. 39 



n glacial river at one time flowed southwest to Lovell and at another time 

 followed the valley of Crooked River for a few miles east and south. So 

 also at the south end of Hogback Mountain Pass, in Montville, a glacial 

 river took two diverging courses, either simultaneously or at different times. 

 In both of these cases the lai-ger flow was along the southwestern course 

 and over hills of moderate height, while the lesser flow took place down 

 valleys of natural drainage and more nearlj- parallel with the glaciatiou. 



Composition. — ^Thcse doposlts are normally composed of water-assorted 

 sediments. The fragments vary in size all the way from the finest clay up 

 to sand, gravel, pebbles, cobbles, bowlderets, and bowlders 3 to 4 and even 

 6 feet in diameter. Gravel is by far the most abundant material. Clay 

 seldom appears except as thin beds in the midst of the coarser sediments. 

 Occasionally there are masses in these deposits closely resembling till, yet 

 in general the finer matter has so plainly been washed out that there is no 

 difficulty in distinguishing them from the unmodified till. They are in fact 

 the till more or less water washed, i. e., the residue left after the fine parts 

 of the till have been removed by glacial water. 



Internal structure. — Most kames and osars are stratified in a very complex 

 manner. Both transverse and longitudinal sections of the kame ridge will 

 frequently show cross bedding. In the longer ridges the oblique laminae 

 generally dip toward the south and obliquely outward toward the sides of 

 the ridge, so that in cross section the strata appear to be arched. In the 

 broad level-topped plains the stratification is often nearlj- horizontal. The 

 strata are sometimes inclined at very high angles, almost vertical, but only 

 locally over small areas, so far as I haA'e observed. In some cases the 

 lines of stratification are curved and twisted, probably the result of dis- 

 tortion since the oiigiual deposition. In a dome or cone the stratification 

 is often quaquaversal, and sometimes monoclinal, either parallel or trans- 

 •verse to the gravel system, as if the deposition took place from the top of 

 the cone downward in all directions, or sometimes only at one side of the 

 channel of the glacial river. 



In some osars a portion of their length shows no lines of stratification. 

 The finer debris has been washed out of them, and the stones even in the 

 pellmell portions are plainly rounded by water. It is more probable that 

 the present pellmell condition of the sediments is due to the obliteration of 

 An original stratification by unequal and irregular settling and sliding 



