All units described below have equivalent-age stratigraphic units throughout the Atlantic Coastal Plain. Names change from one location to another in the literature. The bibliography provides a selected list of references that will help you get started towards more detailed research. Cretaceous and Tertiary units that crop out onshore also exist in the subsurface offshore where they grow progressively thicker southward and eastward on the continental shelf. Pleistocene and Holocene deposits are complex and represent a host of glacial, non-glacial terrestrial, nearshore and marine environments.

Quaternary and Holocene Deposits

HOLOCENE DEPOSITS - The modern beach and barrier islands around the New York Bight represent reworked sand material that began accumulating during a slow-down in sea level rise that began about 3-4,000 years ago. These modern coastal deposits overly older Holocene estuarine and fluvial sediments deposited behind barriers that developed during a period ranging from 12,000 to about 7,000 years ago. (These old barrier deposits are partially eroded and/or buried by younger sediments. These barriers existed anywhere from 2 to 20 kilometers seward of the current shoreline when sea level was approximately 20 to 40 meters lower. On the continental shelf these ancient barriers are currently supplying sediment to offshore sand ridges. Sand along the Hudson River and on Staten Island displays an abundance of angular feldspar and lithic fragments indicative of fluvial sedimentation in the harbor region when sea level was lower. Modern anthropogenic sediments and human activity has modified nearly all coastal and nearshore marine sedimentary environments.

WISCONSIN GLACIAL TILL - Wisconsin glacial deposits are apparent everywhere throughout Long Island, across northern Staten Island and in northern New Jersey. Glacial till consists of unstratified mix of clay, silt and sand with a mix of rock material ranging from pebbles to giant boulders (derived from all rock source areas ranging from Manhattan to Central Quebec). On Long Island the terminal moraine is represented by two ridges that extend the length of the island: the southern, older Ronconcoma moraine and the northern, younger Harbor Hill moraine along the Sound. The terminal moraine extends across central New Jersey along a sinuous line from the vicinity of Perth Amboy to around the Delaware Water Gap on the western side of the state. Outwash sand and gravel deposits (altered by soil-forming processes) cover much of southern Long Island, southern Staten Island and areas south of the terminal moraine in New Jersey. Varved lake clays and swamp peat cover areas flooded by lakes.

GARDENERS CLAY - This poorly consolidated clay underlies Wisconsin Age glacial deposits throughout southern Long Island and has been interpreted as occurring beneath the modern barrier spit of Sandy Hook. The Gardeners Clay contains a rich estuarine fauna with abundant foraminifera. Many of the fossils described in the paleontology of beach deposits of this website are probably derived from the Gardeners Clay or equivalent strata. The unit probably represents high-standing seas between advances of the latest Pleistocene (Wisconsin) glacier.

COLUMBIANA GROUP (early to late Quaternary) consists of three named units - the Pensauken, Bridgetown, and Cape May formations (oldest to youngest, respectively) - each represents different depositional environments throughout the region. The Gardeners Clay is probably a marine equivalent to the Pensauken Formation. Active research in the region will no doubt refine the correlation problems between Pleistocene and Holocene sedimentary deposits as investigations proceed on glacial deposits, and lacustrine, swamp, terrestrial, fluvial, estuary, nearshore and marine shelf deposits in the Bight region.

CAPE MAY FORMATION - (Late Pleistocene to Holocene) - The Cape May formation consists of surficial silts, sands and quartz-rich gravels along the coastal region of New Jersey and represents coastal beach and barrier sand deposits and back bay estuarine deposits. The source of the sand is mostly from the Delaware River drainage supplemented by shelf sands and longshore drift sand from the Mid-Atlantic region. The progessive reworking of Cape May deposits is the source of much sand on the New Jersey coast.

PENSAUKEN FORMATION - (Late Pleistocene) - Wisconsin till unconformably overlies this unit that crops out along a trend from Staten Island to Trenton, NJ and southward along the Delaware River valley. The unit consist of mixed detritus (eroded from older glacial material and exposed Coastal Plain formations) that was deposited in fluvial flood plain environments. The existence of the Pensauken formation suggest that, for a time, the major drainage from the pre-Wisconsin glaciers was southward from the New York area toward Trenton into the Delaware River drainage. Pedogenic weathering of the sediments suggest that it was deposited during a warm interglacial period.

BRIDGETOWN FORMATION - (early Pleistocene?) - The precise age of the Bridgetown Formation is unclear, however, it consists of a deeply weathered mix of silt, sand, and gravel and represents fluvial environments. The Bridgetown probably represents sedmentation during an earlier, pre-Wisconsin interglacial stage. (Isphording & Lodding, (1969) state that the Bridgetown and Pensauken formations are virtually indistinguishable along the coastal areas. Both units lack fossils.)

Tertiary Units

BEACON HILL FORMATION - (Pliocene?) - An iron-stained sandy quartz and quartzite-rich gravel deposit on top of the highest hill in Monmouth County, NJ (373 feet) probably represents a Pliocene fluvial gravel equivalent to late deposition the Cohansey Formation. The Beacon Hill caps Apple Pie Hill and other small hills in the Pine Barrens region.

COHANSEY SAND - (late Miocene to early Pliocene) - The formation consists of medium to coarse-grained arkosic quartz sand (well stratified and cross-bedded), with thin clay lenses and quartz and quartzite pebble conglomerate. The unit represents a range of sedimentary environments ranging from fluvial to transitional marine environments (swamps, deltas, lagoons, beach sand, and shallow open marine shelf). Sediments at the base of the Cohansey appear to fill broad fluvial channels carved downward into the underlying formations (down to the Tilton in the Atlantic Highlands region). Many beds within the unit are heavily cemented by iron; these ironstone sand and gravel depositons form a resistant hilltop caprock in the Highlands region. The Cohansey represents most of the surface deposits throughout the New Jersey Coastal Plain and is well exposed on hills and roadcut and sand pits throughout the Pine Barrens region. All fossil material appears to be leached out of the Cohansey (possibly by processes similar to the acid waters and bog-iron formation currently active in the Pine Barrens region. The unit ranges in thickness from a several meters on hilltops to more than 150 feet on the western side of the coastal plain.

KIRKWOOD FORMATION - (middle Miocene) - The Kirkwood Formation is missing from the Atlantic Highlands section beneath the Cohansey Sand. Further south the formation consists of a clayey to silty mudrock, massive sand, and thin pebble lenses deposited in a sublittoral to nearshore environments. The unit is equivalent to the Calvert, Choptank, and St. Marys River formations in Maryland and Virginia. The sparse occurrence of Calvert cliffs fauna in beach pebbles suggest that the Kirkwood-equivalent strata on the continental shelf is fossiliferous. (This unit has been suggested as time equivalent to the formation of the late Tertiary Schooley Peneplane throughout the mountainous Appalachian region.) The bottom of the Kirkwood sits unconformably in top of older Tertiary units. The thickness is in the range of 100 to 300 feet in the Pine Barrens region.

SHARK RIVER FORMATION - (Eocene) - This unit is also missing beneath the Cohansey Sand in the Atlantic Highlands region, however, it crops out along the creek banks of the Shark River (as the name applies) and contains sharks teeth. The unit consist of a sandy, carbonaceous glauconitic marl and quartz sand. It lies conformably on the Manasquan below. Some researchers do not differentiate Shark River from the underlying Manasquan Formation.

MANASQUAN FORMATION - (Eocene) - This unit is missing in the Atlantic Highlands region, however, it crops out along creek bottoms southward along the Jersey Shore. It consists of a mixed shaley and sandy marl with abundant apatite pellets and siderite concretions, with fossils rare or absent. Thickness (including Shark River) in the range of 50 to 200 feet.

VINCETOWN FORMATION - (Paleocene to Eocene) - The Vincetown consists of quartz sand with phosphatic pellets and glauconite ranging form nearly trace to nearly 100% in some beds (glauconite being most abundant at the base of the unit where it appears gradational with the underlying Hornerstown). Near the shore fossils are absent, however, the unit displays bioturbation structures. Elsewhere on the Coastal Plain it is extremely fossiliferous containing abundant foraminifera, bryozoa, and a prominent basal shell bed containing Oleneothyris harlani, Gryphaea dissimilaris, and bone fragments. Thickness is in the range of 50 to 100 feet.

HORNERSTOWN FORMATION - (Danian, early Paleocene) - A drastic change in fauna is represent at the base of the Hornerstown in New Jersey. This is a reflection of both a mass extinction even as well as a hiatus in deposition. The formation is lithologically similar to the Tilton consisting of a green glauconitic quartz sand. Cretaceous fossils have been noted reworked upward into the basal units. Fossil in the Hornerstown include gastropods, pelecypods, and other vertebrate bone material. The unit displays heavy bioturbation.

Late Cretaceous Units

TILTON FORMATION - (late Maastrichtian, Cretaceous) - The Tilton is a massive "olive to evergreen" green glauconitic quartz sand which is locally clay-rich and silty. The unit displays an abundance of iron-staining and locally bears limonite and hematite crusts and concretions. Locally glauconite constitutes as much as 80% (or more) of the sand, making portions of the formation an economic greensand in the central Coastal Plain. Fossils, mostly poorly preserved molds and casts of pelecypods, Camptonectes, are common, whereas a richer marine fauna occurs further southward in central New Jersey. The unit displays heavy bioturbation. The formation is in the range of 20 to 25 feet thick.

REDBANK FORMATION - (Maastrichtian, Cretaceous) - The Redbank Formation consists of gray to red sand deposited in nearshore environments. Subaerial exposure at the end of "Redbank time" resulted in the leaching of shell material and the alteration of glauconite to limonite (hence the red color). A lower brownish- black micaceous sand unit is called the Sandy Hook Member and displays abundant concretions in bioturbated horizons and has been described as locally fossiliferous. The upper Shrewsbury Member is yellow to orange-gray sand. The unit is a approximately 120 feet thick near Sandy Hook along the valley of the Navesink and Shrewsbury rivers, but grows progressively thinner until it eventually pinches out landward.

NAVESINK FORMATION - (early Maastrichtian, Cretaceous) - The Navesink consists of peloidal glauconitic marl and sand that is locally thick bedded or crossbedded, and is locally clay-rich. Fossils are very abundant in some areas. Carbonaceous matter and phosphatic material, especially at the base. Mollusk fossils are abundant in the lower and middle portions of the unit. Common Navesink fossils include Belemnitella americana, Expgyra costata, Expgyra cancellata, Pyncnodont sp., Ostrea falcata, Ostrea mesenterica, Choristothyris plicata, and many others. (An small collection of Navesink fossils is on diplay at the visitor's center at Poricy Park, Monmouth County, NJ). The fossils occur in concentrated horizons within the unit. The fuana suggest a marine shelf environment. It ranges in thickness between 65 to 45 feet throughout the Atlantic Highlands region.

MT. LAUREL FORMATION - (latest Campanian, Cretaceous) - The Mt. Laural is very similar in appearance and composition to the underlying Wenonah with the exception that it contains abundant micaceous, glauconitic sand which is locally cross-bedded. The unit contains an abundance of phosphatic peletal material and bioturbation features; siderite concretions commonly fill burrows. The unit is about 25 feet thick near Sandy Hook but pinches out landward over a distance of several miles beneath an unconformity beneath the overlying Navesink Formation. The boundary between the underlying Wenonah is undifferentiated in most areas east of the coastal area. Common Mt. Laurel and Wenonah fossils include sharks teeth and bone, shell molds, etc.

WENONAH FORMATION - (late Campanian, Cretaceous) - The Wenonah consists of micaceous quartz and silt and is rich in organic material (mostly silt-sized lignite fragments) and pyrite (in very fresh exposures). The unit ranges in thickness from 35 to 55 feet along Raritan Bay, inland the upper part of the unit is exposed intermittently along creek banks. Phosphatic nodules, siderite concretions filling bioturbation structures, and thin sand beds are common near the top of the unit. Sharks teeth and fossil shell molds are common along with bone fragments and teeth of fish, reptiles, and swimming dinosaurs near the top of the unit. Sedimentation patterns reflect storm-dominated depositional patterns on a shallow shelf environment. The thickness of the formation measures in the range of 70 to 100 feet.

MARSHALLTOWN FORMATION - (middle Campanian, Cretaceous) - The Marshalltown consists of greenish-gray massive quartz-rich, glauconitic sand, silt and dark, micaceous clay. Pyrite and siderite concretions, some displaying evidence of boring and reworking, are abundant at the base of the unit. Other than traces of lignite and bioturbation, fossils are scarce in the unit. The thickness of the formation is between 15 to 20 feet.

ENGLISHTOWN FORMATION - (early Campanian, Cretaceous) - The Englishtown consists of clay, slit and sand which locally displays lamination, thin- to thick- bedding, and cross stratification. Fossils are generally scarce. Locally the unit contains lignite beach-type sand deposits. The upper-most bed display bioturbation with burrows locally filled with glauconitic quartz sand from the unconformable overlying Marshalltown Formation. The formation ranges from 20 to 150 feet in thickness.

WOODBURY SHALE - (early Campanian, Cretaceous) - Dark gray clay mud of the Woodbury Clay is exposed in excavations and along the shore of Raritan Bay near Cheesequake State Park, NJ. The gray carbonaceous shale contains pyrite and bioturbation features of a marine or lagoonal environment.

MERCHANTVILLE FORMATION - (late Santonian to early Campanian, Cretaceous) - Conformably overlies the Magothy Formation and consists of mixed sand and clay units representing nearshore and shallow marine depositional environments. It is poorly exposed around the southern side of Raritan Bay. It interfingers with the overlying Woodbury Clay. The thickness of the unit measures between 20 and 100 feet.

MAGOTHY FORMATION - (Coniacian and Santonian, Cretaceous) - Unconformably overlies the Raritan Formation. The Magothy Formation is beneath Quaternary glacial cover throughout most of Long Island, the south shore of Staten Island, and is fairly well exposed in small outcrops and excavations around Raritan Bay. The Magothy is subdivided into units: the Oldbridge Sand Member, the Amboy Stoneware Clay Member, and Cliffwood Beach Member (oldest to youngest, respectively). The Magothy represents nearshore and alluvial depositional environments, similar to the Raritan Formation. The thickness ranges between 10 and 200 feet.

RARITAN FORMATION - (Cenomanian, Cretaceous) - In the Raritan Bay region the Raritan Formation unconformably overlies Newark Basin and older rocks, representing the beginning of a series of major transgressions and regressions of the seas during Cretaceous time. The Raritan consists of clay, sand, lignite, and gravels representing progradational alluvial plain, coastal and neashore marine environments. Very well exposed in unglaciated regions around the western end of Raritan Bay. Subdivided units include the Raritan Fire Clay, Farrington Sand Member, Woodbridge Clay Member, Sayreville Sand Member, and South Amboy Fire Clay Member (oldest to youngest, respectively). The Sayerville Sand Member is famous for its amber-bearing lignite lenses, insect remains, fossil wood and leaves, and pyrite nodules. The Sayreville fossil beds have yielded an astonishing amount of information about life in the Late Cretaceous.

POTOMAC FORMATION - (early and late Cretaceous) - A moderately well sorted and crossbedded, quartz sand with quartz and quartzite pebbles deposited in fluvial environments. The Potomac Formation is the basal sequence of the Cretaceous system in southern and central New Jersey (it is not recognized beneath the lower Raritan Formation in the bay area). The thickness is reported in the range of 250 to 800 feet.

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