Ransome. ] 



The Great Valley. 



38) 



river itself, as it leaves the Sierra, continues its southwesterly course 

 for more than two-thirds of the distance across the valley, be- 

 fore bending sharply to the northwest to take its way along the 

 valley-axis. 



The existence of natural gas beneath the city of Stockton, in 

 the middle of the lower part of the San Joaquin Valley, has led to 

 the prosecution of considerable deep boring, and has been produc- 

 tive of most interesting results. Some of these wells are over 2,000 

 feet deep, and one is reported to have reached a depth of 3,000 feet,* 

 but in no case has the bottom of the unconsolidated fluviatile 

 deposits been reached. The material passed through consists of 

 fine sands and clays, with occasional beds of coarser sand and 

 gravel. Logs of wood have been found up to 340 feet in depth, 

 fresh-water shells belonging to living species at 600 feet.f and "sand' 

 gravel and cobblestones" at 1,042 feet. There can be little doubt 

 that these deposits indicate an actual subsidence of the valley floor 

 at this point to an extent of at least 2,000 feet during Pleistocene 

 times. 



The Tulare Valley. — As already stated, this valley is separated 

 from the San Joaquin Valley proper merely by a low alluvial divide 

 at about latitude 36 40'. It is the widest portion of the Great Valley, 

 and, according to Blake,."); is 70 miles wide by 1 50 long, and includes 

 7,500 square miles. It has no regular drainage to the sea, and it is 

 doubtful whether the water from Tulare Lake itself ever finds its 

 way into the San Joaquin River, although reported, by hearsay, to 

 do so at certain seasons, by Blake and Fremont. This low divide 

 has apparently been formed by the projection of alluvial fans of low 

 angle into the valley by the San Joaquin and Kings Rivers. The 

 latter river, after issuing from the foot-hills, curves to the south 



*The information here made use of in regard to these wells is mainly taken 

 ' from the Eighth, Tenth, and Twelfth Annual Reports of the State Mineralogist, 

 1 888- 1 894. 



t These shells were collected by Mr. W. S. T. Smith, and are now in the 

 Museum of the University of California. The exact depth from which they 

 were obtained is rather uncertain, resting upon the testimony of one of the 

 workmen engaged in the boring. 



% Pacific R. R. Reports, Vol. V, Geology, page 190. 



