The lower-middle Miocene Kirkwood Formation predominantly consists of packages of delta-front quartz sands overlying prodelta clays. These packages reflect the strong influence of one or more riverine sources of sediments in New Jersey at the time.

Facies within the Kirkwood Formation follow a predictable succession within sequences: 1) a basal unconformity, 2) lower shelly quartz sand deposited in inner neritic environments, 3) a medial silty clay deposited in prodelta environments, 4) an upper quartz sand deposited in delta front environments; and 5) an upper unconformity.  The upper sands generally comprise aquifers of the upper part of the Highstand Systems Tract whereas the silty clays are confining units of the lower part of the Highstand Systems Tract.

Kirkwood clay
Clay-rich facies from the Kirkwood Formation (Ocean View core ; 571-572 ft).

Kirkwood Sand
Sand-rich facies from the Kirkwood Formation (Ocean View core; 475-476 ft).