526 THE JOURNAL, OF “GEROLOGY, 
channels, while their deepening gorges are being constantly car- 
ried back towards the crest of the great divide. The cycle of the 
last movement is not yet ended; and the change in level of the 
region is probably going on now as rapidly as it ever has in past 
geological time, and as rapidly as oscillations of the land surface 
usually take place. 
From the foregoing it may be inferred that since the original 
deposition of the Ozark series, the rocks have been profoundly 
eroded, and that the later formations which are known to have 
covered in great part the Magnesian beds of the uplift have been 
almost entirely removed during the periods of emergence. 
As yet, then, the exact geological age of the different parts of 
the Ozark series is not determined, but the horizons where the 
proper lines should be drawn are foreshadowed, and with the pas- 
sage of another season it is believed that the question, both faunally 
and stratigraphically, will be satisfactorily settled. 
CHARLES ROLLIN KEYES. 
