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Mineral Resources On-Line Spatial Data

Wildwood Member of the Kirkwood Formation

Wildwood Member - New member named for a well drilled at Wildwood, Cape May County. Typically consists of a very fossiliferous, micaceous, darkgray clay-silt interbedded with fine- to medium-grained, pale-gray-brown sand in lower half of the member. The upper half of the member is more sandy (mostly fine-grained, micaceous quartz sand), thin-bedded to laminated, commonly interbedded with thin-bedded, gray-brown, micaceous clay; wood fragments are common. The basal contact with the underlying unit is sharp and has considerable relief. A 1-m (3-ft)-thick bed of gravel (1 cm (0.4 in) in maximum diameter) with pieces of quartz and worn shells, commonly occurs along the contact. Thickness of the unit varies widely because of the undulating basal contact. The maximum thickness, 80 m (262 ft), was penetrated in the Wildwood well. At the Island Beach well (290019) at Island Beach State Park, Ocean County, the Wildwood is over 30 m (98 ft) thick. The lower 6 m (20 ft) consists of thick interbeds of fine- to medium-grained, massive to locally thick-bedded, extensively bioturbated, micaceous quartz sand and dark-brown and grayish-brown silty clay. The middle part is mostly massive to finely laminated, dark-gray to gray-brown silt to clay. The upper 6 m (20 ft) consists of fine- to coarse-grained, locally gravelly, thin- to thick-bedded sand interbedded with the clay and silt. The age of the Wildwood was determined from diatoms and strontium-isotope age estimates of mollusk shells. The diatom assemblages in this unit fall within Andrews (1988) ECDZ 2, thus indicating a considerable unconformity between this member and the overlying Belleplain (ECDZ 6). ECDZ 2 is in the Delphineis ovata Zone and contains the characteristic diatoms Coscinodiscus lewisianus, Delphineis lineata, Rhaphidodiscus marylandicus, Rhaphoneis fusiformis, R. margaritata, R. wicomicoensis, Sceptroneis caduceus, S. grandis, and S. hungarica. Strontium-isotope analyses on shells from this interval indicate an age range of 17.4 to 15.5 Ma (Sugarman and others, 1993). The isotopic and paleontologic ages suggest that the Wildwood Member straddles the early-middle Miocene boundary (Langhian-Burdigalian boundary). Pollen from the Wildwood has warm-temperate affinities in the lower part and mixed warm- and cool-temperate affinities in the upper part suggesting an overall cooling of the climate during the time of deposition. Collectively, the Wildwood and Belleplain Members constitute the section that Woolman (1889-1902) assigned to his "great diatom bed".
StateNew Jersey
NameWildwood Member of the Kirkwood Formation
Geologic agemiddle and lower Miocene, Langhian and Burdigalian
Original map labelTkw
Commentspart of the Kirkwood Formation. Subsurface unit shown in cross section (NJ002) with different description that surficial units.
Primary rock typeclay or mud
Secondary rock typesilt
Other rock typessand
Lithologic constituents
Major
Unconsolidated > Fine-detrital > Silt (Bed)very fossiliferous, micaceous, darkgray clay-silt interbedded with fine- to medium-grained, pale-gray-brown sand in lower half of the member. The upper half of the member is more sandy (mostly fine-grained, micaceous quartz sand), thin-bedded to laminated, commonly interbedded with thin-bedded, gray-brown, micaceous clay
Unconsolidated > Coarse-detrital > Sand (Bed)very fossiliferous, micaceous, darkgray clay-silt interbedded with fine- to medium-grained, pale-gray-brown sand in lower half of the member. The upper half of the member is more sandy (mostly fine-grained, micaceous quartz sand), thin-bedded to laminated, commonly interbedded with thin-bedded, gray-brown, micaceous clay
Minor
Unconsolidated > Fine-detrital > Clay (Bed)very fossiliferous, micaceous, darkgray clay-silt interbedded with fine- to medium-grained, pale-gray-brown sand in lower half of the member. The upper half of the member is more sandy (mostly fine-grained, micaceous quartz sand), thin-bedded to laminated, commonly interbedded with thin-bedded, gray-brown, micaceous clay
Incidental
Unconsolidated > Coarse-detrital > Gravel (Bed)very fossiliferous, micaceous, darkgray clay-silt interbedded with fine- to medium-grained, pale-gray-brown sand in lower half of the member. The upper half of the member is more sandy (mostly fine-grained, micaceous quartz sand), thin-bedded to laminated, commonly interbedded with thin-bedded, gray-brown, micaceous clay
Map references
Dalton, R. F., Herman, G. C., Monteverde, D. H., Pristas, R. S., Sugarman, P. J., Volkert, R. A., 1999, New Jersey Department Of Environmental Protection, Bedrock Geology and Topographic Base Maps of New Jersey: New Jersey Geological Survey CD Series CD 00-1; ARC/INFO (v. 7.1) export file: geology.e00, scale 1:100,000, unit description files: cslegend.pdf and nlegend.pdf, metadata: metast.pdf.
Unit references
Dalton, R. F., Herman, G. C., Monteverde, D. H., Pristas, R. S., Sugarman, P. J., Volkert, R. A., 1999, New Jersey Department Of Environmental Protection, Bedrock Geology and Topographic Base Maps of New Jersey: New Jersey Geological Survey CD Series CD 00-1; ARC/INFO (v. 7.1) export file: geology.e00, scale 1:100,000, unit description files: cslegend.pdf and nlegend.pdf, metadata: metast.pdf.
Owens, James P., Sugarman, Peter J., Sohl, Norman F., Parker, Ronald A., Houghton, Hugh F., Volkert, Richard A., Drake, Avery A., Jr., and Orndorff, Randall C., 1998, Bedrock Geologic Map of Central and Southern New Jersey: U.S. Geological Survey Miscellaneous Investigations Series Map I-2540-B, scale 1 to 100,000, 8 cross sections, 4 sheets, each size 58x41.
Andrews, G.W., 1988, A revised marine diatom zonation for Miocene strata of the Southeastern United States: U.S. Geological Survey Professional Paper 1481, 29 p.
Sugarman, P.J., Miller, K.G., Owens, J.P., and Feigenson, M.D., 1993, Strontium isotope and sequence stratigraphy of the Miocene Kirkwood Formation, southern New Jersey: Geological Society of America Bulletin, v. 105, no. 4, p. 423-436.
Woolman, Lewis, 1889-1902, Report on artesian wells in southern New Jersey, in New Jersey Geological Survey, Annual Report of the State Geologist: [variously paged].
Geographic coverageCumberland - Ocean

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