214 J. S. DILLER GEOLOGY OF CALIFORNIA AND OREGON. 



the latest A. ramorus and A. batesii, belong to the upper half of the Horse- 

 town beds and extend much farther northward in its series, overlapping 

 the older raetamorphic rocks. 



From the North fork of Cottonwood creek the Horsctown beds extend 

 far westward, crossing the range between Yallo Bally and Bully Choop 

 mountains along the Hay fork road, and an isolated fossiliferous area of 

 them nearly five square miles in extent occupies Bedding creek basin in 

 Trinity county, at the northwestern base of the Bully Choop mountains. 

 Everywhere beyond the limit of the Knoxville beds the Horsctown beds 

 rest, with a marked unconformity, directly on the metamorphic rocks. 



The Chico beds have a wide distribution in southern California, and 

 to the northward underlie the Sacramento valley, with outcrops on 

 both sides. At Elder creek, on the western side of the valley, the Chico 

 beds rest conformably on the Horsetown beds. They extend north- 

 ward, holding the same relation to the Horsetown beds until near Bed- 

 ding, where the Horsetown beds run out and the Chico beds rest uncon- 

 form ably on the metamorphic rocks. This unconformable contact be- 

 tween the Chico beds and older metamorphic rocks, including at least 

 Carboniferous, Triassic and Jurassic strata, has been traced around the 

 northern end of the Sacramento valley, and, by way of the Great bend of 

 Pit river, Mount Shasta, Henley and Ashland, farinto ( Oregon. There is 

 good reason for believing that the Chico beds which extend beneath the 

 lavas of the southern portion of the Cascade range connect with those 

 recognized on Crooked river, Oregon* 



At a number of places in the Klamath mountains there are remnants 

 of Cretaceous rocks in which these mountains were once enveloped, but 

 this covering has nearly disappeared by erosion. To enter into the de- 

 tails of their distribution Avould lead beyond the proper limits of this 

 paper. Let it be sufficient to say that their distribution shows that the 

 Klamath mountain region was almost, if not wholly, beneath the sea 

 during the closing days of the Cretaceous. f 



On Elder creek, in Tehama county, California, the Chico, Horsetown 

 and Knoxville beds are all present. The Knoxville beds extend from 

 this place only a few miles to the northward ; the Horsetown beds ex- 

 tend beyond them in that direction at least 25 miles, while the Chico 

 beds stretch still further in the same direction far into Oregon. The Cre- 

 taceous section thins out rapidly in the same direction by the successive 

 dropping out of the earlier beds. On Elder creek the Cretaceous is ap- 

 parently over 20,000 feet thick, at Ono 8,800 feet, and further northeast- 



* Bulletin 33, U. S. Geol. Survey p. 19. 



fSince the paper on fche geology of Lassen peak was written i Eighth Ann. Rept. ('. s. Geol. Sur- 

 vey, p. 411,412) the subsidence has i o found much greater Hum was a! firs! supposed, so that the 



Cretaceous island may have wholly disappeared near the end oi thai period. 



