188 The American Geologist. March, 1892 
side, is an exposure easily recognized from Keokuk several miles 
away. Pebbles of granite are occasionally found, but are not 
numerous. Chert fragments are frequent, and often occur in 
accumulated masses. I have also observed geodes distributed 
sparingly through the bed. Lime concretions occur in the upper 
portions. The deposit is mostly coarse and porous, and is some- 
times used for molding purposes. This bed has sometimes been 
considered as representing the more important formation towards 
the south, called the Orange Sand. Hilgard, who first studied 
these beds (Orange Sand), regards them as the southern equiva- 
lent of the northern drift, considering the materials of the two to 
be ‘essentially correspondent,” and asserts ‘‘that there are but 
two essential particulars to distinguish it from the beds of the 
northern drift proper; first the absence or at least great scarcity 
of erratic rocks proper, * * * and secondly the great preva- 
lence of limited deposits of ferruginous sandstone or conglom- 
In the drift of the northern states the ferruginiz- 
ing process has played but a subordinate part.”* Until quite re- 
erate. 
cently this view has been sustained by nearly all of the geologistst 
who have written upon the subject, those of Illinois alone dis- 
senting, and insisting upon their pre-Pleistocene character. The 
latter view has recently been confirmed by investigations in east- 
ern Arkansas under the auspices of the state geological survey. R. 
E. Call,who has made a special study of the Orange Sand, gravels, 
and Loess of Crowly’s ridge, says that he regards the Tertiary 
age of these beds as unequivocal. In a contribution to the same 
report, R. D. Salisbury sustains this opinion from confirmatory 
evidence gathered along the lower Ohio. Briefly,the reasons ad- 
duced by the latter for this disposition of the beds, are as follows: 
1. The unconformity which exists between the loess and the under- 
lying gravels and sands. 
The profound weathering and oxidation which these formations 
underwent previous to the deposition of the loess. 
3. The constitution of the gravels of Crowley’s ridge precludes 
their reference to the Pleistocene.§ 
wo 
*American Journal of Science, 2nd Ser. No. 123, p. 315. 
+Safford, Am. Jour. Sci., 1864, Vol. 37, p. 361. 
Dana, J. D., Manual of Geology, p. 548. 
Leconte, Elements of Geology, p. 548. 
Loughridge, Jackson Purchase Region, Ky. Geol. Surv. 1888. 
tArkansas Geological Report, Vol. 11, 1889, p. 126. SSame, p. 224. 
