250 = J. D. Dana—Driftless Interior of North America, 
and that they mark stages of rest during emergence of the con- 
tinent from the ocean which covered it. 8. That the river ter- 
races and the valleys which they line, were formed after the 
drainage system had been reéstablished by withdrawal of the 
“yer to a level below that at which the streams had previously 
owed. 
ArT. XXXV.—On the Driftless Interior of North America ; by 
JAMES D. DANA. 
1. Driftless area of Central and West-Central North America, 
€ portions of two of Mr. Schott’s charts (see 
beyond); one (No. 1) giving the lines of equal precipitation for 
*Vol. ix, p. 312. Further, vol. x, p. 385, and vol. xiii, p. 80. The connection 
between the distribution of the ice and the amount of peal paisiiod is appealed to 
also in ibid., v, 206, 1873, and illustrated from Mr. Schott’s chart. 
