444 SIDNEY PAIGE 
flank of considerable steepness; second, that they present a remark- 
able evenness of surface, when viewed from.a sufficient distance to 
reduce the prominence of recent dissection; and third, that they 
truncate rock structure without any decided evidence of selection. 
As indicated in Fig. 1, the boundary between the gravel and the 
bench of hard rock may be divided into two parts; one where ero- 
sion has revealed a depositional unconformity, the other where 
faulting has disturbed this normal relation. The slope of the bench 
Fic. 2.—Vertical scale double the horizontal. 1 square=1 mile 
in continuous with the slope of the gravel sheet, and is astonishingly 
regular from the edge of the gravel to the mountain front. Nota- 
ble is the irregular depositional boundary in the northern portion 
where the gravel rises gently upon the bench nearly to the foot of 
the mountain scarp; notable also the straight boundary where 
faulting has altered this relation. 
It seems that the conditions here are peculiarly fortunate and 
diagnostic. If the faulting had not occurred, it is doubtful whether 
the bench would have been exposed. Even the northwestern por- 
tion would probably have been more completely covered. As it 
