20 



GEOLOGIC GUIDEBOOK ALONG HIGHWAY 49 



[Bull. 141 



E g H 



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GEOLOGIC MAP 



CALIFORNIA 



SCALE 

 40 80 



MAJOR ROCK UNITS 



!-''>! Cenozoic volconics 



I H Cenozoic sediments 



Cre+oceous sediments 

 Jurossic Fronciscon group 



Mvsozoic - Poleoioic 

 me+qmorphic- qronilic rocks 

 Bosin- Ronqes and Mojave Desert- 

 rock -complex 



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ilti^^i,' 





nc fault 



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FIG. 5. Geologic map of California showing major rock units. Reprinted from 

 California Din. Mines Kept. 40, pi. 8. 



Flo. 6. .4, Block diagram illustrating Cretaceous Sierra Nevada topography. The 

 upturned edges of bedrock controlled the drainage pattern, which was later 

 inherited by streams of the early Eocene period. After Matthet, V. 8. Qeol. 

 Survey, Prof. Paper 160, 1930. 



B, Block diagram to show tilting of the Sierra Nevada and its effect on stream 

 cutting. Erosion, prior to the tilting, planed down the surface and exposed 

 the granite, leaving only occasional fragments of the intruded metamorphic 

 rock-bodies as roof pendants. The streams, at the point where they leave 

 their mountain canyons and enter the Great Valley, form alluvial fans. 

 After Matthes, V. 8. Geol. Survey Prof. Paper 160, 1930. 



