820 =. W. Hilgard on the Quaternary of Mississippi. 
where upon the Orange Sand,’ we find a deposit consisting usu- 
ally of a mellow brick clay, or loam, more or less ferruginous, 
and snbject to inconsiderable variations in accordance with the 
character of the underlying materials. It might in some regions, 
therefore, be accounted a mere surface disintegration of older 
strata, but for the fact that in others it is distinctly developed as 
an independent stratum; its maximum thickness observed being 
about twenty fvet, while the average lies perhaps between five 
and ten. 
As to its geographical distribution, it is not a little remarka- 
ble that, while the preceding and succeeding stages, VIZ, the 
Bluff and the Hommock deposits, show a very obvious relation 
to the drainage of the country, such is the case only to a very 
limited extent with the Yellow Loam itself, which seems orlgl 
nally to have overspread the country very evenly, with on the 
whole a slightly increasing thickness toward the larger chan- 
nels, such as the Mississippi, lower Tallahatchie, Yallabusha, 
Big Black, and Tombigby. he local uniformity of its material, 
the absence of stratification-lines in its own mass, and the horl- 
supposition of its being either « lacustrine or marine deposit. » 
The extensive denudations which succeeded its deposition ren- 
ed upon some of the highest ridges of the state, which were 
above water even then, it is found manifestly in situ both on 
peters elevated above the general surface, and in regions 4 
undred or more feet lower, immediately adjoining the former. 
And since in all cases its character varies more or less in accord: 
ance with that of the underlying material, which enters into its 
composition and therefore testifies of a certain amount of denud- 
ing action, it would seem that the conditions of its deposition 
could be satisfied only by the assumption of the submergence 
of the surface under water locally deep, but always gently flow- 
ing—not sea-water, for the deposit is void of fossils—vor for the 
same reason, precisely such as that which deposited the Bluff 
formation. On the same ground, and on that of its inconsider- 
able thickness, we must also conclude that but a short space ° 
time was occupied in its deposition, 
* Or rather, upon an amorphous and ill-defined transition stratum of “hardpat,” 
usually one to three, but locally as much as fifteen feet in thickness ($ $35). 
