288 The American Geologist. m^^'- ^^os. 
wliicli a.yain in tlic main assumed their prc-Iowan valleys. It 
appears therefore that this process of re-excavation of the up- 
land valleys has continued to the present witliout the super- 
position of any later record, accom])anied in the river valleys, as 
already stated in No. 5, in some latitudes by re-excava(ion of 
the Wisconsin till and terraces, and in more southern latitudes 
by a gradual increment in the higlit of the tloodplain of the 
Missouri. \\'hat more natural thereiore, or more inevitable, 
than that along" the rivers the lowan loess should be foimd 
lodged on all pre-Iowan rock-spurs and l)luffs, and that all the 
inequalities of the pre-Iowan surfaces should be expressed 
with greater or less clearness in the contours of the present 
loessian surfaces. In case, under pre-Iowan decay, a firm rock 
layer, overlain by an easily weathered mass of shale, had form- 
ed a projecting shelf on which h.ad gathered a mass of geest 
and semi-geest in pre-Iowan time, as appears to have been the 
fact at the Concannon tunnel, the same sheltering surroundings 
would also preserve the lowan loess on that rock-shelf and 
might produce, as appears to be the fact at the Concannon 
farm, an imperfect, blind terrace-like platform. Such plat- 
form, however, would in no sense be an lowan fluvio-glacial 
terrace, although its materials, in their present pose, might 
date from lowan time, and be a part of the lowan fluvio- 
glacial deposits. 
23. Again, this final summary statement as to the origin 
of "the little relic-bearing deposit" testifies to the needless- 
ness of the "academic statement" as to scour-and-fill, since it 
makes no appeal to scour-and-fill. 
The human remains were in. or below, a loess which rises 
and extends over the surrounding blufi^s, formed by the meth- 
ods of distribution known as lowan. As shown in No. 22. the 
Missouri river never flowed, since Wisconsin glaciation, at low 
stage, ainy higher than it does at present, and therefore never as- 
high as the floor of the tunnel, and never formed, since Wiscon- 
sin time, a floodplain as high as the top of the relic-bearing de- 
posit. The circumstances of the fluctuation of the Missouri 
from one side to the other of its channel, of scour-and-fill, of 
wash from the hill-sides, of changes in the floodplain of the 
tributary valley, of the demolition of the Carboniferous blulifs 
and of the Kansan sheet of the drift, are still going on, have 
