Figure 3. In the early 1900s, oil was regarded as infinite in supply, as more and more giant and super giant oil fields were discovered. Early methods of extraction included hand-dug wells, then impact tools, and finally rotary drilling bits in 1901. The wells shown here were drilled along the Kern River in central California. Like almost all wells, they require pumping to lift the oil to the surface—very few wells flow under their own pressure which is rapidly depleted. The pumping method shown here was to link the pump jacks (A) over a wide area by cables (B) to a single engine that pulled them up and down to pump the oil. All oil costs money to produce, and those costs have grown dramatically over the history of the industry and will continue to grow as more and more difficult oil is produced. J.H. Lipps image, 1960.