200 Transactions of the Academy of Science of Si. Louis 
race is more mature than is that of the Cuivre or any other ter- 
race studied in his region. It thus appears that the Boeuf Terrace 
antedates all the other and can hardly be attributed to material 
from the Wisconsin ice sheet. So it would seem that the Boeuf 
Terrace is associated with either the Nebraskan or the Kansan 
ice sheet. The presence of numerous erratics makes it appear 
that correaltion with the Kansan ice sheet, whose front was 
parallel to the Missouri River in this vicinity, is more probable 
than correlation with the Nebraskan. 
Although the terrace may be traced in tributaries of the Mis- 
souri on both sides of the river from Oetters to Hermann, careful 
search has failed to reveal the presence of a terrace of this de- 
scription anywhere east of Oetters along the Missouri River or 
anywhere at all along the Mississippi River as far north as the 
study has gone; namely, to Winfield. Either the terrace has been 
entirely removed in these localities, or it never was formed there. 
Evidence seems to favor these later alternative. In several places 
limestone-cored hills project through the Cuivre Terrace. If the 
Boeuf Terrace existed at such points, it would almost certainly 
appear; but it does not. Figure 8 shows such a situation. 
The Boeuf Terrace seems to have been formed in a lake 
formed by the damming of the Missouri River. The presence 
of numerous erratics indicates that some ice front, probably the 
Kansan, formed the border of part of the lake. It seems likely 
that the ponding of the water was due to an ice dam which crossed 
the Missouri River. The lake in which the terrace was formed 
must have had an elevation of at least 570 feet. Leverett4 once 
made the suggestion that the Missouri River once might have 
flowed into the valley of of the Meramec in the vicinity of Grays 
Summit during the Nebraskan age. Since the lowest col in 
the bed rock at Grays Summit has an elevation higher than 650 
feet, it hardly seems likely that the waters from the lake that 
formed the Boeuf Terrace escaped at that point. The outlet for 
the lake has not yet been discovered and it may have been 
through. or under the ice itself, as Chamberlain’ suggested in 
the case of an ice dam on the Ohio River, 
