 Early well drilling in the area was almost always of a "wildcat" nature, with numerous failures, as finding oil-bearing units in the hidden structure was mostly guesswork, until enough borehole logs were available to begin to build a subsurface lithologic model.During the 1920s the price of oil dropped gradually with new discoveries, including giant fields in the Los Angeles Basin, the Central Valley, and Texas; and with the Great Depression, and the 1930 discovery of the enormous East Texas field, the price of oil dropped as low as ten cents a barrel.Drilling during this period was greatly reduced, as the cost to open a new well was unlikely to be recouped unless an exceptional reservoir could be tapped, and few drillers were willing to take this risk, particularly in a field where success was so spotty.