diller] GEOLOGIC AGE OF KOCKS OF KLAMATH MOUNTAINS. 65 
the finely striated forms of A. reticularis), Schizophoria striatula (Schlotheim) , 
Cladopora sp. undet., Fistulipora (the same species as the one in the conglomer- 
ate) , and crinoid stems. 
These fossils also indicate Middle Devonian age. At first I supposed that the 
Schizophoria would prove the horizon to be Upper Devonian, but the presence of 
A. missouriensis and Cladopora do not support this view. On the other hand, 
S. striatula abounds in both the Middle and Upper Devonian, and our dependence 
for age determination must therefore rest upon the other fossils. 
That the associated slates and conglomerates with fossil fragments 
are younger than the Middle Devonian is suggested also by some 
plant remains collected by Mr. Storrs a few miles northwest of Sla- 
tonis. Among these Prof. William M. Fontaine recognizes, with some 
donbt, Brachyphyllum, and he remarks "that Brachyphyllum is most 
developed in the Jurassic and lowest Cretaceous. If we may regard 
this plant as belonging to that genus, then, so far as its evidence goes, 
the strata are Jurassic or lowest Cretaceous. But as the generic place 
of the fossil can not be determined decidedly, and the amount of 
material is so small, the age can not be certainty fixed. A Jurassic 
age is indicated." The evidence thus far tends to confirm Mr. Her- 
shey's views 1 as to the age of the Bragdon slates. 
In September, 1900, a number of Cretaceous fossils which Dr. Stan- 
ton regards as of Horsetown age were found in the valley of the 
Upper Illinois River near Waldo and Kerby, Oreg. Owing to the 
presence of this isolated area of soft Cretaceous sediments, a broad 
valley has been developed at this point. To the northwest the valley 
sediments are limited by a great mass of peridotite, and in the oppo- 
site direction they are cut off by the older rocks of the Siskiyou 
Mountains. Similar isolated areas of closely allied Cretaceous beds 
basined in older rocks are well known 3 along Graves Creek in Ore- 
gon, and Redding Creek in California. 
West of each of the Horsetown localities mentioned A ucella- bearing 
rocks have been found, along Van Deusen River above Hydesville, 
and along the stage road at Shelly Creek, Cal., 20 miles southwest of 
Waldo, Oreg. Near the coast in Oregon there is a great thickness of 
Aucella-he&ving rocks separating the Chico and Horsetown beds from 
those of pre-Cretaceous age. 
As to the rocks of that portion of the Coast Range which lies south- 
west of Mad River, a Cretaceous form of Aucella (determined by Dr. 
Stanton) was found along Van Deusen River above Hydesville, and 
it is certain that some of the sandstones and shales are younger than 
the rocks which form the mass of the Klamath Mountains. Imperfect 
fossils were found in the limestone near Laytonville. Among them 
Dr. Girty reports "a large but indeterminable gasteropod, and a num- 
ber of small organic bodies which appear to belong to the genus Mitch' 
1 Am. Geologist, April, 1901, Vol. XXVII, p. 2:38. 
2 Fourteenth Ann. Rept. U. S. Geol. Survey, Pt. II, 1894, PI. XLV. 
Bull. 100—02 
