diller.] RELATION OF KLAMATH MOUNTAINS TO COAST RANGE. 61 
the Klamath Mountain region was largely, if not wholly, submerged. 
This conclusion is sufficient to show that if a Cretaceous peneplain 
is found anywhere in the Klamath Mountains it must be limited to 
the summits of the high peaks. 
On the other hand, it appears very probable that the Klamath pene- 
plain corresponds to the Miocene plain 1 of the Sierra Nevada. The 
Miocene age of each plain appears to be fairly established by paleon- 
tologic evidence, and their continuity is suggested not only by their 
juxtaposition but by their fossil flora. Differences in amount and 
character of deformation, hardness of rocks, climatic conditions, near- 
ness to the sea, and probably also time of elevation ma} r be cited 
to account for differences in stage of topographic development since 
since the peneplain was uplifted. 
RELATION OF TOPOGRAPHY OF KLAMATH MOUNTAINS 
AND COAST RANGE. 
The topography of the northern end of the Coast Range may be said 
to be mature. But this is true only on account of the gentle relief above 
the canyons. The same is true of the topography of the adjacent 
Klamath Mountains, and yet the cycle appears somewhat less advanced 
and the canyon stage more profound than in the Coast Range. This 
difference may be attributed to — 
1. Differences of composition. The Coast Range is composed chiefly 
of Mesozoic sandstones and slates, but among these are numerous 
though generally small masses of a basaltic intrusive and chert, as 
well as glaucophaue and other very local schists. The rocks, for 
the most part, have been crushed to small fragments, and are therefore 
comparatively easily eroded. They were once capped by Neocene 
sediments of still greater softness, and they played an important role 
in the early cycles of the Coast Range. On the other hand, the 
Klamath Mountains are composed of much older rocks. Large masses 
of schists and slates, with some limestones and igneous rocks, such 
as peridotite, serpentine, gabbro, and diorite and allied forms, are 
abundant and cover large areas. These rocks are in general much 
harder than those of the Coast Range, and it would not be expected 
that the topographic development would be so far advanced. 
2. The position of the terranes with reference to the direction of 
drainage has much to do in determining the degree of relief. In the 
Coast Range the drainage is largely parallel to the strike of the forma- 
tions. Wherever the streams cut across the strike they flow in more 
prominent canyons. In the case of the Klamath River, especially 
the part from the mouth of the Trinity to Happj^ Camp and beyond 
is across the schistose structure, a feature which contributes no small 
amount to the boldness of the scenery. 
1 Tertiary revolution in the Topography of the Pacific coast: Fourteenth Ann. Rept. U. S. Geoi. 
Survey, Pt. II, L894, pp. 397-434. 
