-♦>>> Till AliK'l'iCHn Giolix/tsf. Xoveiiibcr, IS'.ll 
littU' iiliovc tlicsi' Itottoins. if :it all. and is (listiiijriiisliMlilc fi-oiii 
the iii(»(U'rn thivial deposits with ditliculty. 
Tile deposits of the first or earlier class arc wholly silts, so far as 
determined l)y us. Our special invest i<i;alions have been chietly 
ciuitined to the I oil miles next helowthe drift iiorder. l»ut they have 
reached, in a less i-onsecutive way. lo .Mississippi and Louisiana. 
After careful an<l })r()tracted search. renew(Ml on successive sea- 
sons, we luivc entirely failed to find any coarse drift connected 
with glacio-tlux ial formations that lie aliovc the liottoni lands, al- 
tliouiih the area is ureal and the exposure by irnllyini^- phenomi'nal. 
The ••oranu.e sands and tjravels " which underlie the ulacio-fiuvial 
silts are non-ulai'ial in character and seem t(» us to he demon- 
straiily j)re-i>lacial. At any rate, the absence of glacial pebbles, 
and even jilaciai sand and silt, from them removes them from any 
need of special consideration in this connection, even if they l)e 
supposed to i>e contemporaneous with the earlier glacial stages, 
for the absence of the glacial material may be taken as showing 
the incompeti'ucy of the uppei' Mississii)))i to bear such material 
southward at that time. 
Silts being then the only demonstrable rei)resentatives of the 
glacial i)roducts borne south during the ealier stages of glacia- 
tion. it is a necessary inference that the land from the border of 
the drift to the gulf was so flat and so low that only slow-moving. 
silt-l»earing currents were formed. Tlu' jiresent c-ui-rent of the 
-Mississippi is eonii)etent to carry coarse sand and small pebitles. 
The currents of the earlier glacial period were therefore less com- 
petent and the country was Hatter than now. 
Concerning the glacio-fluvial deposits that lie l)eneath the pres- 
ent river bottoms, or lie so U)w as to be indistinguishable from 
the llu\ial deposits of the present river, little of a positive nature 
can be as.serted. So far as known from borings and other evi- 
dences, they are not notably coarse. To the northward, in the 
glaciated region, they rise altove the |)rcsent rivci- bottoms and 
have l>een traced back to their origin, so that we know the ap- 
proximate attitude of the surface at the time that they were 
formed. They may thei'cfore be set aside heri' and discussed 
later. 
//. Pill HDiiii nil i>f till Drift Bmili r. Tile naturi- of the drift 
border in the axis of the Mississippi basin, where it reaches 
fartherest south, is in itself siirnificant of the attitude of the sur- 
