754 T. C. CHAMBERLIN 



Missouri river is given by Abbott as twenty feet at St. Joseph, 

 above Lansing, and as thirty-five feet at its mouth; its extreme 

 range is somewhat greater than this. 



Further, if the mouth of the tributary be blocked by the upper 

 flood-plain beyond the time of the latter's growth the wash from 

 the tributary will build a delta, or fan, upon it, and this further 

 growth will continue until the w r aters from the tributary valley 

 have built up a suitable gradient for themselves across the flood- 

 plain to the river. This only holds good in valleys of incompe- 

 tent drainage which cannot cut and maintain a trench for them- 

 selves. If the tributary valley has a large, competent stream it 

 will maintain a channel-way across the flood-plain to the river, and 

 less aggradation will result from the shifting of the meanders, 

 but that is not the case in hand. 



If excuse for this academic statement is needed it is found 

 in its special application to the case in hand; for either 

 action of the kind just set forth is to be accepted as an elucida- 

 tion of the case, as in the preferred interpretation that follows, 

 or it is to be shown incompetent for such elucidation before we 

 permit ourselves to go back of this action to earlier agencies. It 

 is a vital principle of good practice that the agencies and phe- 

 nomena nearest at hand be first considered, and, if the case 

 requires, be eliminated, before recourse is had to more remote 

 agencies. This is peculiarly true when, as in this case, the 

 agencies closest at hand in time have quite certainly swept away 

 the most of a more ancient record in making their own. 



THE SPECIAL CASE. 



The topographic environment of the relic-bearing deposit. — The site 

 of the human remains is at the bottom of a small, short, rather 

 steep-sided valley opening out on the flood-plain of the Missouri 

 river. More specifically, the valley is less than a mile long, and 

 less than half a mile wide, measured from crest to crest, and is 

 about 160 feet deep at its mouth. The slopes on either hand are 

 rather steep and nearly meet at a rather sharp angle in the axis 

 of the valley, except that this is modified by the channel or dry 

 run which forms narrow bottoms and little bluffs near themouth, 



