i6o Conservation Reader 



gether has been estimated to be equal in value to a river of 

 oil flowing several hundred thousand barrels each day. In 

 many districts the gas was nearly gone before people dis- 

 covered its great value. It is impossible for us to realize 

 the waste which this represents. 



It has taken Nature a long time to make the oil and gas 

 which we are losing. When she began this work, the oil 

 regions which have been mentioned were beneath the sea. 

 In its waters lived countless numbers of minute organisms, 

 as well as fish of many kinds. As they died, their bodies 

 accumulated in beds which finally became thousands of 

 feet thick. Then the currents of the water changed and 

 sand and mud were washed over these beds, burying them 

 deeply. 



Finally the bottom of the sea was lifted and became dry 

 land. The movement squeezed and folded the rocky layers 

 made of the skeletons of the animals and plants. The soft 

 parts of their bodies held in these rocky layers produced a 

 greenish or brownish oil and gas. The gas tried to escape 

 from the rocks, for they were hot and it wanted more room. 

 In some places it foxmd openings through the rocks and 

 escaped to the surface, usually bringing some of the oil with 

 it. The gas was lost, but a part of the oil remained, form- 

 ing deposits of tar. In other places the oil and gas could 

 not reach the surface, but found porous, sandy rocks into 

 which they went and remained until the oil driller found 

 them. 



The tar springs, or "seepages," indicate to the oil pros- 

 pector where deposits of oil may possibly be found. He 

 examines the country about and, selecting a favorable place, 

 drills a well. If he is successful, he will strike oil-bearing 



