[2] The major road through the field is Jayne Avenue, which runs east to west, connecting Interstate 5 to Coalinga.

California State Route 33 runs from north to south, west of the field, joining with Jayne Avenue.

The uppermost productive units in the field are sand lenses within the Miocene-age Temblor Formation, named the Smith and Allison respectively from upper to lower.

The most productive unit, and the first to be discovered, is the Leda Sands, which reside in the Miocene-age Vaqueros Formation, underlying the Temblor.

The impermeable Salt Creek member of the same Vaqueros Formation is above the Leda Sands, trapping the oil and preventing its natural upward movement.

While the enormous Coalinga field is but a few miles away, in a similar anticlinal structure, it is richly productive at under 1,000 feet (300 m) below ground surface, and hence was easier to exploit.

[6] As the Leda Sands had proven to be spectacularly productive, operators began searching for other rich petroleum deposits, and in 1949 found the second-most productive unit, the Allison Sand; in 1954, the rich North Leda unit; in 1957, the Gatchell pool, and in 1962 the Dessel pool.