66 GUIDEBOOK OF THE WESTERN UNITED STATES, 



erosion 



were rounded into pebbles by waves or streatfi^s before the overlying 

 Carboniferous (Bragdon) formation was deposited. In geologic 

 language the Bragdon formation rests unconformably on the slates, 

 p.lip.rt<^. and limostonos which make UD the Kennett formation. The 



formation to the Kennett formation 



mi 



can not be seen from the train. The Kennett formation is succeeded 

 on the south by igneous rocks — a light-colored quartz porphyry and 

 a greenish lava (meta-andesite — that is^ altered andesite). These 

 two rocks ai-e closely connected with the occurrence of the large copper 

 deposits of Shasta County. The altered andesite is older than the 

 Kennett formation and represents volcanic action in early Paleozoic 

 time. The porphyry is intrusive and was probably injected into the 

 rocks with which it is associi)ted in late Jurassic time. From this 

 locality to Redding, a distance of about 20 miles, these are almost 

 the only rocks visible along the railroad. 



Pitt station is near the mouth of Pit River, where that stream joins 

 the much smaller Sacramento. 'A branch railroad on the left (east) 



leads to Ileroult, where there is an extensive deposit 

 ^'**- of hon ore and an electric smelter, and to Copper 



Elevation GS8 feet 

 Seattle 678 miles. 



Hill 



mines. 



mile bevond Pitt is tunnel 



the right (west)^ there is exposed a narrow north-south belt of Devo- 

 nian slates (Kennett formation). This belt lies in a large area of 

 meta-andesite. It probably represents material which once lay 

 horizontally on top of the andesite but which, when the rocks were 

 bent into sags and arches by regional pressure — folded, as geologists 

 say — was caught in a sag (syncline) and finally squeezed together 



narrow 



northemmo; 



M 



Kennett. 



Elevation G 70 feet 

 Seattle 680 miles. 



northwest of the town. The ore of this region is 



' 'c and occurs 



m the quartz porphyry referred to above. The 



om 



pigment 



escape into the open air. By this mc 

 3 is saved in the form of zinc sulphate 



Fossil-bearmg limestone belonging to the Kennett fomiation 

 (Devonian) caps the ridges on both sides of Backbone Creek. Lime 

 and ground limestone, used as a fertilizer, are both made here. 



