388 The American Geologist. December, 1894 
slight fractures and faultings. That was the last uplift of 
the Ozarks. Previously there were undoubtedly stream chan- 
nels in the Ozarks. After the close of the Paleozoic there 
were additional fractures, greater erosions and deeper chan- 
nelings by the streams. In southern Missouri the eroded val- 
leys are 300 to 450 feet deep, in northern Missouri they may 
have been 200 or 300 feet, but, excepting near the Missouri 
river, they are rarely to be seen over 150 feet deep, reaching 
200 at the extreme. The Missouri river shows a valley gen- 
erally one to two miles wide, with an inner channel or trough 
eroded before glacial times but during the Ice age filled up 
from 40 to 90 feet, 
Proportional to the size of the stream and character of the 
bluff are the size and depth of the stream's trough. The 
streams in southern Missouri are partly filled with a local 
drift, Away from the larger streams the country is hilly or 
rolling, dependent on the character of the rock structure. 
Where the country rock is limestone, the channels and hills 
are rugged. The Coal Measures being largely composed of 
sandstones and shales, with only thin limestone beds, the ero- 
sion there has been greater, but the slopes are more gentle. 
We often observe limestone-capped ridges ; when the erosion 
is long continued they remain as mounds. To this is due the 
interesting and beautiful scenery of the prairies of western 
Missouri. Where the strata consist of beds of shales and 
sandstone capped by harder limestone, the last serves as a 
protecting cap to the softer underlying beds, retarding their 
entire erosion. A line of such mounds may be traced along 
the base of the upper Coal Measures from Bates county north- 
eastward through Cass, Johnson, Lafayette, and thence north- 
wardly. Along this line are seen ridges several miles long, 
and occasionally a single mound 80 or 100 feet above the lower 
plains with an area of probably half an acre on the summit. 
Other mounds may be near, or distant two, five, or fifteen 
miles. The visible depressed or eroded area may be a pris- 
moid 100 feet deep by five or ten miles in one direction and 
twenty miles or more in another. From the summit of one of 
these mounds we may gaze on a hundred farms occupied by 
an industrious and thrifty people. 
