388 OSCAR VHS HEIRS AE, 
nants on this shelf, fixing its age as that of the andesite eruption. 
I regard it as a sort of coastal plain of erosion, baseleveled by 
the body of water in which the Ione sandstone was deposited. 
After the Ione formation was completed, the andesitic lava 
flowed over the sandstone area and lapped over on to this 
narrow coastal plain. This andesite, from its lithologic char- 
acter and from its relations to the underlying Ione formation 
and an overlying basalt, may be correlated with the andesitic 
tuffs and lavas partly burying the Sierra Nevada peneplain. 
Hence, Bagley Flat is the equivalent of the Middle Pliocene 
peneplain of the Sierra Nevada region. 
Back of Bagley Flat, two mountains, Bagley Mountain and 
another unnamed, rise rather steeply to altitudes respectively of 
4,437 and 3,905 feet, and were monadnocked on the baselevel 
of the Middle Pliocene to the extent approximately of 1,600 
and 1,100 feet. West from here, as far as the Sacramento River, 
the Klamath mountains consist of a group of peaks, of which 
these two mountains are members. While the general surface 
slopes to the south and the peaks reach altitudes of 4,000 to over 
6,000 feet, there is not sufficient uniformity in their height to 
suggest a dissected peneplain. These peaks have the aspect 
rather of monadnocks, and the relation of several of them to 
Bagley Flat shows that they belong to the same category as 
the monadnocks of the Sierra Nevada region. This portion of 
the Klamath region was nearly all residual, baseleveling only 
being effected on a narrow strip around the head of the Sacra- 
mento valley. It is a significant fact that the Klamath moun- 
tains rise much more abruptly on the side of the great valley 
than do the Sierra Nevada Mountains. This is beautifully 
exemplified by a view toward the north from Redding, where 
Bear Mountain and other peaks in the vicinity appear to rise 
sharply from the plain. 
A view toward the southeast from Brock Mountain shows a 
number of flat-topped ridges bearing a marked resemblance to 
eastern dissected peneplains, but this is quite local, and I do not 
know its significance. If any older peneplain than the Middle 
