Earth's deep treasure, petroleum, lies buried. Man must probe for it with drills and derricks. Elizabeth Olds explains simply, letting pictures do much of the talking, how George Bissel, a young New York lawyer, adapted the derricks used in salt-well drilling to bring to the surface the oil which he suspected lay on his land in Titusville, Pennsylvania. His conviction brought an oil bonanza to the town. At 1020 feet, in 1901, the Hammil brothers struck a geyser which gushed forth a hundred thousand barrels of oil a day before it was harnessed -- bringing to Beaumont a new population. Between porous and non-porous layers of rock are trapped this vital resource -- oil. This compact and superbly illustrated book focusses on the why of oil and how man procures it. There is cursory treatment of distribution and consumption. Text is large and language is terse. Excellent complement to social studies units on natural resources. The gay colors and boldly patterned diagrams are understandable, artistic and twentieth-century.