36 The American Geologist. January, it)Oi. 
ly The Lafayette base-level would be difficult to detect here, 
were it not that a few remnants of the Lafayette stream-grav- 
els have been found, notably near Duncweg, about six miles 
due east of Joplin. They indicate that to Pliocene erosion may 
be charged the upper one-third of the valleys, thus placing the 
Lafayette base-level at fifty to seventy-five feet beneath the 
main Tertiary peneplain so well represented by the general 
upland surface. There are rock-terraces along Shoal creek, 
south of Joplin, but they seem of later age than the Lafayette. 
A somewhat similar rock-terrace along the Spring river in 
Cherokee county, Kansas, is doubtfully referred to the same 
category as the terraces of James river and Flat creek in 
Stone and Barry counties, Missouri, known to be of Layfay- 
ette age. 
In short, that after the completion of the main Tertiary 
(presumably Tennesseean) peneplain, there ensued another 
(and vastly shorter) cycle of Tertiary erosion, resulting in the 
formation of a type of valleys which have been designated 
"basin valleys," because they are broad and shallow and have 
gently sloping sides, of supposably Lafayette age in their com- 
pletion, may be gathered from evidence scattered all over the 
Ozark highland region. This implies, beyond doubt, an ele- 
vation of the province in general of an epeirogenic character, 
but also to a slight extent orographic, as is indicated by the 
250 to 300-foot depth of erosion in the White River basin, in 
place of the normal seventy-five to one hundred feet of nearly 
the whole remaining portion of the Ozark region. It is this 
differential character of the uplift which strengthens the evi- 
dence. 
Before closing this subject, I desire to remark that the 
same or a like system of basin valleys trenched beneath the 
main Tertiary peneplain is a recognized feature of the geo- 
morphology of northwestern Illinois and contiguous areas, 
and are known to me to exist in the inter-montane valleys of 
Pennsylvania and New Jersey. May they not be recognized 
in the southern Appalachian province, whose physiographic 
history is otherwise so nearly like that of the Ozark province? 
The Ozarkian valleys. — The narrow, crooked valleys 
trenched beneath the Lafayette base-level include the erosion 
of the Glacial and post-Glacial subdivisions of the Quaternary 
