760 



T. C. CHAMBERLIN 



aggradation deposit is unknown to me, but it is probably not 

 many feet, as the aggradation stage has but recently been 

 inaugurated by the detour of the river. On the north side the 

 spur next the Missouri bottoms grades down to this lower grada- 



Fig. 8. — View from near the mouth of the tunnel looking northeastward across 

 the bottom of the tributary valley, showing the gradation of the footslope of the north 

 bluff into the Missouri bottoms seen at the right. 



tion plain and the combination of lower slope and present 

 bottom deposits is similar to that of an earlier date on the south 

 side which contains the human bones (Fig. 8.) 



The present aggrading washes have made a little bottom in 

 the lower twenty rods of the valley, with meanders and little 



