310 The AtnericMi Geologist. May, is99 
of central Kansas. The Atchison beds thus have very nearly 
the same limits assigned to them as a quarter of a century later 
Prosser proposed for the Wabaunsee. They occupy over four- 
fifths of the interval that the Wabaunsee occupies in the vicin- 
ity of the northwest corner of Missouri. For this reason At- 
chison appears to be the only name that can be legitimately 
used for the shales between the Forbes and Cottonwood lime- 
stones. 
The Atchison shales are 500 feet thick on the Missouri 
river. Near the base is at least one seam of coal of sufficient 
thickness for profitable mining. This is the Nodaway coal, 
which lias a very considerable extent in northwestern Missouri 
and southwestern Iowa. The Aspinwall coal seam in south- 
eastern Kansas is probably a part of the same stratum. 
These extensive shales impart certain peculiarities to the 
topography of the area occupied by the Nodaway coal that are 
not noted elsewhere in the Missouri region. The soft rocks 
have permitted a moderately uniform plain to be worn out. 
In Missouri Marbut has designated the plain the Maryville 
lowland, thus recognizing it as one of the important relief feat- 
ures of that state. The shales, moi^feover, occupy the bottom of 
the Brownville syncline. Owing to the attitude of the strata, 
their softness, and the peculiarities of drainage in the region, 
by which the lowland plain has been formed and the contrasts 
of relief reduced, little information has been heretofore ob- 
tained regarding these shales. They have been scarcely noted, 
though they are two and one-half>=times as thick as the whole 
upper coal measures w^ere once thought to be. Since their ex- 
tent has been recognized the Atchison shales have come to as- 
sume more and more importance until it has come to be sus- 
pected that eventually they may possibly have equal rank with 
the Des Moines series. 
Cottonwood Limestone. The Cottonwood limestone has been 
adopted as the uppermost member of the Missourian series. 
The rock was widely known as a quarry stone, long before 
its importance as a geological formation was recognized, it be- 
ing called the "Cotton-rock," or "Cottonwood Falls rock" 
or "Cottonwood stone." Thus, the last two names have crept 
into geological literature and it seems advisable to adopt the 
name, especially since other geographic names that have been 
