140 WALKS AND TALKS. 



auger enter below the surface of the oil, the reaction of the 

 gas forces the oil to the surface, and a "flowing well" 

 exists. When the oil becomes lowered to the place of 

 the perforation, gas escapes till the pressure is relieved. Then, 

 if any oil remains, it may be pumped. Lastly, the water 

 may be pumped. If the auger enters the cavity below the 

 surface of the water, the reaction of the gas forces first water 

 to the mouth of the well ; then when the bottom of the oil 

 is lowered to the orifice, oil is forced out till its surface sub- 

 sides to the orifice, when, finally, the gas escapes. No oil 

 now remains in the cavity. 



In California an oil-producing shale extends through the 

 Eocene (Tertiary) of the Coast Ranges; but south of San 

 Francisco these strata mostly stand on edge, and most of the 

 fluid oil has escaped, leaving large quantities of tarry as- 

 phaltum, which hardens on exposure to the air. North of 

 San Francisco, however, these shales are horizontal, and oil 

 has accumulated in considerable quantities. But the chief sup- 

 ply of petroleum in California is found in the less disturbed 

 regions south of San Francisco, chiefly in Los Angeles and 

 Ventura counties. The total product of the state in 1884 

 was 262,000 barrels. 



In foreign counties, the most productive territory is the 

 Baku region in Russia, near where the Caucasus abuts 

 against the Caspian. Here is an area of 14,000 square miles 

 which is producing, under treatment assimilated to that em- 

 ployed in America, quantities which promise to interfere se- 

 riously with the export of American oil. Six hundred wells 

 have been bored, and one spouting well is represented to 

 have produced 50,000 barrels a day. The most copious Penn- 

 sylvania well flowed 9,000 barrels a day, and the most pro- 

 ductive Canadian well, 7,500 barrels. 



