Cambrian For'natlon of St. Francois Mfs. — Kcycs. 53 
of the Fredericktown.* To l)e sure, the title St. Joseph ap- 
pears in the lead and zinc report of Missouri, published in 
1895, but it was merely a name in a table of provisional for- 
mations, and was given as an alternate with St. Francois lime- 
stone. In spite of this fact, this name might have been adapt- 
ed at the time in the special report on the ^Une la ]\Iotte district 
and used in place of Fredericktown had it not been for the 
circumstance that essentially the same name had been previous- 
ly proposedf in due form for an important terrane in north- 
ern Arkansas — the St. Joe marble formation. 
The LeSueur dolomytej of the Mine la Motte district, rep- 
resents only about the lovv^er third of what was later denom- 
inated the Potosi limestone. The latter name, moreover, like 
St. Joseph, was merely mentioned in the gene^^al lead and zinc 
report. As a matter of fact, little is really knowm about the 
stratigraphy of what is colored as the Potosi limestone on the 
map accompanying the bulletin of the United States Geological 
survey. And it is exceedingly doubtful whether the beds 
which have been termed the LeSueur in the Mine la Motte dis- 
trict are represented at all in the Potosi limestone further 
north near the typical locality. 
EDITORIAL COMMENT. 
THE SUPPOSED RECENT Sl'RMERGENCE OF SIP.KRTA. 
Prof. G. F. Wright finds that the country skirting the great 
central Asiatic table-land is loaded with the fine deposit known 
as "Loess." This consists of water-borne deposit for the most 
part though in the east the aeolian origin as maintained by 
professor Richthofen, seems very probable. If this material 
is of glacial origin ultimately, as is the case in other parts of 
the world, this view merely ex])lains its mode of deposition. 
It must, then, be the "glacier-milk" of the glacier-system of the 
central plateau brought down by the rivers that flow down the 
long slopes and dropped on tlie lowlands adjoining. 
But professor Wright says that the altitudes of the strata of 
loess are such as to prove a subsidence of the whole region in- 
* Missouri Geo!. Siir , vol. i.\. 189r). pt. iv. p. 4-8. 
f Arkansas Geol. Siir., .\iin. Kcp. 1 .S9(i. vol. iv, 1893, p. 25.S. 
iAIissoiin Geol. Sur., vol. ix, pt. iv, 1S9.5, p. r>'J. 
