PHYVSIOGRAPHY OF KLAMATH MOUNTAINS 153 
ing, and containing evidence of volcanic activity. Two members 
have been generally recognized, the Ione formation, and the 
Tuscan tuff. Mr. Diller states that the Jone formation on 
Little Cow Creek, Shasta county, has a thickness of five hundred 
feet and that to the east of this there isa great thickness of clays, 
sands and gravel which are sufficiently indurated to be called 
shales, sandstones, and conglomerates, and which he calls Ione. 
The lower half of the Ione formation on Little Cow Creek is 
composed chiefly of sandstones and shales, with a bed of coal 
and carbonaceous material twelve feet thick, with an abundance 
of fossil leaves. 
In the basin of Shasta valley similar beds occur with plants 
and carbonaceous layers, and entirely similar deposits occur 
along the western slope of the Cascades in the Rogue River 
valley. These beds are best exposed a few miles to the east 
and to the north of Ashland, Ore. Four miles north of Ash- 
land, where the series has been well exposed by faulting. they 
have a thickness of about three hundred feet. Similar deposits 
occur also throughout the Trinity basin, as at Weaverville, Big 
Bar, Hay Fork, and Hyampom. In the Hyampom valley, in 
western Trinity county, these beds are well exposed, and con- 
tain layers of coal and carbonaceous matter, and the leaves of 
many Neocene plants, including the Sequoia. 
Lake systems of the Neocene-—As in the Cretaceous, so also 
during the Neocene period, the basin to the north of Mount 
Shasta appears to have been separated from the Sacramento and 
Trinity valleys. Inthe northern basin the Ione deposits form 
almost a continuous line from Shasta valley northward to Rogue 
River, or even farther. Regarding their extent eastward, there 
has been considerable conjecture. They have not yet been def- 
nitely traced beyond the summit of the Cascades; but this may 
be due to their being buried beneath volcanic eruptions. The 
Ione deposits are evidently those of fresh water, the period 
being one of extensive lakes lying to the south and east of the 
Klamath Mountains. In the Rogue River basin, which, as here 
used, includes the basin of the Klamath Lakes, it has yet to be 
