Geologists have long speculated about the possibility of finding as-yet undiscovered oil resources in Mesozoic strata, including the Jurassic, deep under the younger and shallower Tertiary strata that host the reservoirs of the producing Cook Inlet oil and gas fields. The source of the oil in these fields lies within the Jurassic sequence, and much oil estimated to have been generated from the Jurassic source remains unaccounted for.