iiLLER.] ORIGIN OF KLAMATH AND BELLSPBING PENEPLAINS. 45 
mils. Tn most cases their distribution associates them with streams 
of to-day, but in some places, especially in the Weaverville belt, they 
are contiguous to no streams at the present time. If the Trinity River 
formerly followed this belt, it is evident that great changes have taken 
place in the drainage since the deposition of these beds. 
The tuff found on Redding Creek, as well as that at Hay Fork and 
Hyampom, appeals to be the western extension of the Tuscan tuff, 
so well developed about the borders of the northern portion of the Sac- 
ramento Valley, and furnishes a sharp time horizon over that region, 1 
Judging from what is known of the volcanic material and the fossil 
leaves at Hyampom and Hay Fork, it is most likely that the deposits 
containing them are Miocene. Strata of essentially the same nature 
as those of Trinity County, but possibly younger, have been observed 
in Lake County and described by Dr. G. F. Becker. 2 Fresh -water 
shells, some leaves, and large bones were found, which Professor 
Marsh considered as very late Pliocene. 
ORIGIK OF KLAMATH A1STD BELLSPRI^G PENEPLAINS. 
That the Klamath peneplain is one of erosion there is no doubt, for 
it cuts directly across the structural features, and is equally inde- 
pendent of the wide range in the hardness of the rocks upon which 
it is developed, but the particular manner of the planation, whether 
subaerial or marine, and if subaerial, whether due to "peneplana- 
tion," as explained by Davis, 3 or to other conditions, as set forth by 
Tarr, 4 Shaler, 5 and W. S. Tangier Smith, ,; may be questioned. The 
determining level of erosion in all cases was that of the adjacent ocean, 
which undoubtedly has been the sculptor of the elevated beaches so 
well developed at various levels along the narrow belt of land between 
the present shore and the elevated edge of the peneplain. The 
sharply denned terraces connected with the elevated sea beaches are 
generally capped by marine deposits. This is not always the case 
close to the landward borders, although in some cases deposits near 
the sea cliff are nearly 50 feet in thickness, with much gravel locally 
rich enough in gold to afford profitable mines. 
Sea cliffs, such as limit the marine deposits on the eastward, and 
beds of sand and gravel such as are common upon these terraces, have 
not been observed anywhere upon the Klamath peneplain. Except- 
ing the coastal edge, where the YVymer beds occur, it is entirely 
devoid of marine deposits, and their absence militates against the 
view that the Klamath peneplain is one of marine denudation. The 
broad expanse of the plain stretching across the range, when com- 
1 Fourteenth Ann. Rept. U. S. Geol. Survey, Part II, 1894, PI. XLV, pp. 414-419. 
-•Mon. U. S. Geol. Survey Vol. XIII, 1888, p. 219. 
3 Am. Jour. Sci., 3d series, Vol. XXXVII, 1889, p. 430. 
1 The peneplain: Am. Geologist, June 1898, Vol. XXI, pp. 351-370. 
5 Bull. Geol. Soc. America, Vol. X, pp. 245-276. 
6 Bull. Dept. Geol. Univ. California, Vol. II. pp. 155-178. 
