CHAPTER VI 

 THE GEOLOGICAL STORY BRIEFLY TOLD* 



"In order to gain the truths of rock history it is necessary 

 to know the processes which cause the results, and the con- 

 ditions under which those processes operate." (Herbert 

 Gregory. ) 



The Beginnings of California Very Remote 



The beginnings of California date far back into the dim 

 ages of the past. The geological story of the State extends over 

 the lapse of time since the beginning of the North American 

 continent. When "The Beginning" was is enveloped in 

 uncertainty. 



"It appears probable that the beginning of Caenozoic was 

 about 60,000,000 years ago; of the Mesozoic about 200,000,000 

 years; and of the Palaeozoic about 540,000,000 years. The old- 

 est rock thus far determined is in Carelia, Russia, and its age is 

 computed to be 1,850,000,000 years. Rock from the Black 

 Hills, at Keystone, South Dakota, records an age of 1,460,- 

 000,000 years. Since the oldest dated rocks are intrusive into 

 still older formations it is probable that the earth is at least 

 2,000,000,000 years old. Thus nearly three-quarters of geo- 

 logic time transpired before the Cambrian, which preserves the 

 first adequate record of life. 



"Jeans has expressed the immensity of geologic time effec- 

 tively in the following simile: 'Let the height of the Wool worth 

 building represent geologic time. We may then lay a nickel 

 on the tower to represent the time of human existence. A 

 thin sheet of paper on this will represent all historic time.' ' 

 (Schuchert and Dunbar, Textbook of Geology.) 



* This chapter is somewhat technical, and may be omitted by the gen- 

 eral reader without losing the thread of the narrative. 



