River ]'aJlei/.s of flie Ozark- Plateau. — Iler.sheti. ;}43 
between the two troughs consists of persistent though some- 
what irregular terraces, known among the settlers as "bench 
lands," which are found near the base of the valley slopes, fre- 
quently changing from side to side as the lower trough may 
approach one or the other of the older valley's borders. These 
"bench lands" are persistent throughout that district, and to 
some extent throughout the Ozarks. Starting near the head- 
waters of the streams, they first appear as a slight relief along 
the sides of the valley bottom. Thence, as the main valley 
deepens, they rise higher above its bottom and become broader 
and more prominent features of the topography. The town 
of Galena in Stone county, Missouri, is mainly built on this 
terrace plane, and many of the farm buildings along the James 
river have been erected on its tlat surface, especiallj^ where, at 
the intersection of valleys, it frequently runs far out in a point 
or cape-like projection. At Galena and in all valleys of that 
vicinity the hight of the terrace above the present streams aver- 
ages from 50 to 60 feet; but where it connects with the broad 
ancient valley of White river, its elevation is considerably over 
100 feet above the stream. Farther on down the latter valley 
in Taney county, Missouri, and in the portion of the Ozarks 
extending into Arkansas through which the White river Hows, 
much of the country near the river, which is described as a 
very hilly upland, is in truth merely a part of the upper 
trough or ancient valley that has been deei)ly excavated bv 
subsequent erosion. 
When first observed by the writer, these terraces were 
thought due possibly to a diversity in hardness of the various 
strata of the bed-rock of the region. It was noticed that the 
valley above the terrace was excavated in the cherty shales 
and limestones of the Lower Carboniferous system, while the 
lower trough was trenched chiefly into the dolomites of the 
Ozark series. But a comparison of erosion I'oi-ms in the east- 
ern Ozarks and the western portion of Missouri made it evi- 
dent that the Lower ( 'arboniferous rocks were harder and 
less easily eroded than the strata of the Ozark series. Further- 
more, in tracing the terrace plane up the smaller valleys, it 
was found to be equally well developed after the Ozark (Uil- 
omites, or "cotton-rock," as they are locally denominated, had 
disappeared under the base of the valleys: and when these 
