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CLARENCE N. FENNER 



followed by the eye for miles along the mountain sides. A typical 

 mountain block of horizontal sediments is shown in Figure 2. On 

 the southeast side of the range the sediments are still the shales 

 and sandstones of the Upper Jurassic, little different lithologically 

 or paleontologically from those on the other side. Structurally, 

 however, this fact is observable — that they dip fairly uniformly 

 away from the range at angles of 10 to 15°. Some typical views 



Fig. 4. — Looking up canyon of Katmai River from Prospect Point. On the 

 left, Mount Katmai in the background, and its lava slopes and cliffs in the middle 

 distance; on the right, the sediments of the Barrier Range. Just above the river 

 level and at the foot of the lava cliffs, surfaces of glaciated sandstone (shown in 

 Fig. 5) were found. Photograph by D. B. Church, 1916. 



are shown in Figures 3 and 4. This difference of attitude of the 

 beds on the two sides of the range may indicate block-faulting 

 and tilting, but this seems remarkably slight evidence to be the 

 only indication of a break of such great length and reaching to 

 profound depths. That profound depths have been reached is 

 indicated by the manner in which the break extends without 

 deviation across fundamentally different surface structures. There 

 is, however, a possibility that the volcanic chain may be situated 

 not directly along the surface trace of the major fracture, but 



