264 



GEOLOGY. 



rest unconformably on the deformed and eroded Eocene 1 (Arago). In 

 British Columbia, there are both clastic and volcanic rocks referred to 

 this period. 



Fig. 443. — Contorted beds of Monterey shale. Mouth of Vaquero Creek, Cal. 

 (Lippincott, U. S. Geol. Surv.) 



Non-marine deposits. — While the sea occupied the southern part of 

 the great valley of California (as far north as the Marysville buttes) 

 during at least a part of the Miocene period, it seems not to have over- 

 spread the northern part, where contemporaneous deposits of estuarine, 



Fig. 444. — Section showing the structure and relations of the Miocene system in 

 the San Luis Obispo region of southern California. Jsl, San Luis formation, 

 Jurassic; Nm, Monterey shale, Miocene; Nrt, rhyolite tuff; Np, Pismo formation, 

 Miocene (?); Npr, Paso Robles formation, Pliocene; Pal, recent alluvium, etc. 



lacustrine, and probably subaerial origin (lone formation) were being 

 made. They consist of the common sorts of clastic sediments, with 

 some coal, iron, etc., and may be continuous, under the later beds 



1 Diller, 17th Ann. Rept. U. S. Geol. Surv., Pt. I, pp. 475-6, and Coos Bay and 

 Port Orford folios, U. S. Geol. Surv. 



