350 The Aviericdrt fieolodist. Di-ccinher, is95 
lion. It tirst attracted iiij attention in the valley of the 
James river, where I found that the terraees or '-benches" are 
covered witli a mixture of river g-ravel. broken chert, clay, and 
sand, which, when a fresh exposure is found, is seen to be 
roughly stratified. An examination of all the valleys in the 
region shows that this particular de])osit is contined to the 
top and sh)pes of the terraces. In some i)hices, notably at the 
town of Galena, it consists of hirge quantities of moderately 
coarse subangular gravel imbedded in a red clay. The thick- 
ness reaches as much as 10 or 12 feet, and its base where ex- 
posed is seen to i-est on smooth and waterworn surfaces of 
the solid dolomite rock. In other places its materials are 
finer and it freciuently consists of a bed of fine sand or loam 
nearly free from ])ebbles. I have picked from the sides of 
gullies quite large masses of transparent quartz crystals that 
have been formed in the loam since its deposition. The color 
of the clays and sands which make up the body of this de- 
posit is prevailingly deep red, locally varying to orange. It 
differs from all the other deposits of the region, — from the re- 
sidual clays and chert gravels on the ridges, by its being a 
river gravel, its bright red color, and slight but distinctly flu- 
vial stratification ; from the present river deposits, b3' its 
color, finer texture (indicating less powerful currents), and its 
elevated position; and from the ('olumbia clays by the pres- 
ence of much gravel, absence of fossils, and red color. 
The position of this deposit indicates that, previous to the 
cutting of the lower canons or present gorges, it lined the 
broad, nearly level bottoms of the Tertiary valleys. In short, 
it is the deposit which constituted the flood-plains of the 
streams just jjrevious to the early Quaternary uplifting of the 
region. As that uplift of the Ozarks appears to have been 
contemporaneous with the post-Lafayette period of elevation 
and rapid erosion immediately succeeding the Lafaj^ette period 
of deposition, it becomes evident that our ancient river de- 
posit must have been laid down during some part of the La- 
fayette period. The nature of the deposit indicates rather 
enfeebled erosion, and the ancient river was struggling with a 
mass of clay and sand, the accumulation of which was prob- 
ably occasioned by a slight subsidence of the region, in con- 
junction with the Lafayette submergence in the ^Mississippi 
