 The field is a structural trap formed by an anticline on the downthrown side of the Vicksburg Fault Zone.The faulting is due to "large-scale gravity slumping", and these types of faults are referred to as growth faults, which are normal faults that occur simultaneously with sedimentation.Most of the oil and half the gas is produced at depths between 4500–6000 feet, from 15 oil reservoirs and 4 gas reservoirs in the Oligocene Frio Formation sandstones deposited during Marine regression, notably the "5900 foot sand", the "5800 foot sand", the "5500 foot sand" and the "5200 foot sand".