Paleontology and Sequence Stratigraphy of the Upper Cretaceous Navesink
Formation, New Jersey
Long Island Geologists Field Trip
October 18, 2003
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file for printing.
Overview of the Navesink Formation
Navesink Formation is an 8 meter thick interval of fossiliferous glauconitic
sand exposed along the eastern margin of the Cretaceous outcrop belt in New
Jersey (Fig. 1).
At the northern end of the outcrop belt in Monmouth
County, the Navesink Formation is
accessable along the banks of Big Brook between Hillsdale
Road and Boundary Road
and along the banks of Poricy Brook, at Poricy
Park on the Middletown-Lincroft
These two localities have long been known to fossil hunters as
excellent places to collect Late Cretaceous marine fossils. Less widely appreciated is the fact that
the Navesink Formation contains an excellent sedimentological record of the
transition from an inner shelf to an outer shelf environment during a sea-level
rise. The changes in environment that
occurred with the changes in sea level are recorded in a sequence of
sedimentary facies defined by distinctive suites of sediments, trace fossils,
and macrofossils. Our objective on
this field trip is to examine the various features that define each facies,
as well as the characteristics of the transitions between facies. These transitions are incompletely
understood, so the interpretations presented on this field trip should be
considered a work in progress.
Nevertheless, the story that emerges of sea level rise on the Late
Cretaceous continental shelf will be clearly seen and some good examples of
Cretaceous fossils will be collected before the day is done.
Figure 1. Geologic
map of New Jersey showing
Cretaceous outcrop and field trip localities.
Navesink Formation in Time and Stratigraphy
Stratigraphic formations and cycles in the uppermost Cretaceous of the
New Jersey coastal plain (after
Owens et al., 1970 and Owens and Gohn, 1985).
of the Navesink sediments has been estimated to range from approximately 70
million years at the base of the formation to approximately 66 million years
at the top on the basis of Sr-isotope age estimates (Sugarman et al.,
1995). Stratigraphically, the Navesink
is placed at the base of the Maastrichtian Stage of the Upper Cretaceous, and
is thus the beginning of the end of the Mesozoic (Fig. 2). The Navesink is also the basal formation
in the last of six depositional cycles developed during the Late Cretaceous
on the Atlantic Coastal Plain. These
sequences of marine sediments were deposited during cycles of sea level rise
and fall (transgression and regression) and are separated from each other by
disconformity surfaces representing intervals during which the coastal plain
was exposed and eroding. The Navesink
records the marine transgression that initiated deposition of cycle 6 and
grades continuously into the overlying Red Bank Sand, which was deposited
during the regressive part of the cycle (Fig. 2). The majority of sediment in the Navesink
Formation consists of glauconite, which occurs as dark green, lobate,
sand-sized grains with surface cracks. Glauconite is an iron-rich mica
mineral that forms diagenetically at the sediment-water interface from clay
minerals. Formation of glauconite
sands occurs on the continental shelf during prolonged intervals of sediment
starvation (Odin and Fullagar, 1998).
Deposition rates for the upper Navesink Formation have been estimated
to be approximately 1 m/m.y. based on formation thickness and strontium
isotope dates from different stratigraphic horizons (Sugarman et al.,
1995). The low rate of sediment
accumulation and scarcity of terrigenous sediment show that the Navesink was
deposited under sediment starved conditions.
The Navesink Formation and Sequence Stratigraphy
A Sequence Stratigraphic Primer (based on Nichols, 1999)
Sequence stratigraphy is a method for
understanding the formation of sedimentary strata within the context of
cycles of relative sea level rise (transgression) and fall (regression). A stratigraphic sequence is basically a
package of strata deposited during a single cycle of sea level rise and
fall. Sequences are bounded above and
below by unconformities, meaning that they are deposited between episodes of
significant sea level fall. Sea level
fall of several tens of meters will cause subaerial exposure of the coastal
plain and downcutting and erosion by rivers draining out to the receding
shoreline. On the shelf, deep water
sediments will be overlain by shallow water sediments. If sea level fall is extensive enough to
expose the entire shelf, then a widespread unconformity surface will develop
– a sequence boundary. There is no cycle order (length or time scale)
implicit in the definition of a sequence - one could conceivably define a
sequence for any order of cycle. In
practice, however, sequences are reserved for packages of strata bounded by
regionally significant unconformities marked by significant erosion on the
shelf and coastal plain.
are packages of strata within a sequence that can be attributed to formation
during particular phases of rising and falling relative sea level (Fig.
3). Systems tracts have also been
called facies tracts because they contain strata from related depositional
3. Cycle of sea level rise and fall
Lowstand systems tract (LST): During a relative fall in sea level the
shoreline moves seaward, exposing the continental shelf. Valleys are eroded into the coastal plain
and shelf and submarine canyons are eroded into the slope. Sediment bypasses the shelf and slope and
is deposited as turbidity currents in submarine
fans on the basin floor. Sediment
fans can also be deposited on the slope.
As relative sea level stops falling sediments may begin to fill the
valleys carved on the shelf, creating a lowstand
wedge. Together, the lowstand
wedge, slope fan, and basin-floor fan deposits form the LST. On most of the shelf, the LST may exist
only as a surface of
Transgressive Systems Tract (TST): As sea level starts to rise, base level
increases and fluvial deposits form in incised valleys. The shelf becomes
flooded again, creating a marine flooding surface as the shoreline migrates landward,
reworking the lowstand deposits or the surface of erosion developed during
sea level fall. This reworked
unconformity surface defines the beginning of a new sequence on the shelf and
is called a sequence boundary. Above the sequence boundary, marine
deposits of the TST are often thin due to sediment starvation as clastic
sediments become trapped in flood plains and estuaries flooded during the
time of maximum rate of rising sea level.
This causes the deposition of a condensed section on the continental
shelf characterized by authigenic sediments such as glauconite. As the rate of sea level rise begins to
decline, rivers begin to build deltas out from the shoreline and clastic
sediments begin prograding across the shelf.
At some point prior to the beginning of renewed deposition of shelf
clastics, the maximum flooding surface
(MFS) – stratigraphic level of maximum relative sea level – is
deposited. Shortly above the MFS the
renewed deposition of allogenic sediments is shown by increasing quantities
of terrigenous mud and sand.
Figure 4. Sequence stratigraphic interpretation of
the Navesink sequence from Miller et al., 1999, Fig. 2).
Highstand Systems Tract (HST):
This systems tract is characterized by aggradation of shelf sediments
and then movement of the shoreline landward again as the rate of sea level
rise slows, stops, and then reverses.
Often this is the thickest part of the sequence because clastics
stored in estuaries during sea level rise are flushed out onto the shelf
during early sea level fall. The upper
boundary of the HST is a sequence boundary, formed as sea level fall
accelerates and begins to expose the coastal plain and shelf to erosion once
Interpretation of the Navesink
Navesink Formation has long been understood to be the transgressive interval
in a sedimentary cycle that includes the overlying Red Bank and Tinton sands
(e.g. Owens et al., 1968). Becker et.
al. (1996) identified a transgressive lag deposit at the base of the Navesink
at Big Brook and other localities and argued that this lag deposit represents
a significant erosional unconformity.
Miller et al. (1999) identify this lag as a major sequence boundary
(Fig. 4). Unfortunately, the lag
deposit is not exposed where it is easily accessible (it outcrops about a
mile upstream from the Boundary Road bridge and is usually covered by
slumping) and we will not be able to view it.
Above this sequence boundary the Navesink Formation preserves deposits
of the transgressive systems tract (TST).
Martino and Curran (1990) describe two distinct lithofacies within the
Navesink, a 0-4 meter transgressive sheet sand
overlain by muddy, glauconite sand.
Miller et al. (1999) describe one meter of clay-silt with reworked
sand pods at the base of the Navesink (Fig. 4), which they interpret to be a
deposit of the lowstand systems tract (LST).
The difference between these two interpretations lies in the placement
of the transgressive surface (TS) which represents the initial flooding of
the shelf during sea level rise.
Martino and Curran (1990) place the TS directly above the erosional
lag at the sequence boundary, whereas Miller et al. (1999) place the TS about
1.5 meters higher in the section, above what they interpret to be a
regressive lowstand tract deposit (Fig. 4).
A Detailed Look at Navesink Facies
We have been looking in detail at
the sedimentology and paleontology at different stratigraphic levels, paying
particular attention to bounding surfaces between facies. Our work has found evidence for four
distinct lithofacies and biofacies overlying the transgressive lag at the
base of the Navesink (Figure 5).
Together, these facies appear to show a progressive but discontinuous
rise in sea level beginning with the erosional lag at the sequence boundary
(Bonelli and Bennington, 2000).
Facies A) A thin basal
interval of fine quartz sand with abundant carbonaceous matter, mud and some
glauconite (average 15% by weight – Fig. 6).
This interval is extensively burrowed, with the distinctive trace
fossil Spongeliomorpha (similar in
form to the better known Ophiomorpha
but with unlined burrow walls marked by longitudinal ridges [Bromley,
1996]). The claws of the callianassid
crustacean Protocallianassa sp. are
occasionally preserved within the burrows at the Big Brook locality. We interpret this facies to be sands
deposited in an inner shelf environment.
These muddy sands must have been sufficiently cohesive to permit
callianassids to excavate burrows without the need to line the burrow walls
with fecal pellets, which would have produced Ophiomorpha traces (Bromley, 1996).
Facies B) A fining-upward interval of muddy, fine to
very fine quartz sand with abundant carbonaceous matter and some glauconite
(average 15% by weight – Fig. 6). This
facies is characterized by a diverse bivalve fauna, including both epifaunal
and burrowing forms, preserved as composite molds in the unlithified sediment. Genera identified include Inoceramus, Trigonia, Crassatellites,
Periplomya (?), and Linearea. Burrows consisting of small (5 mm
diameter), sand-lined tubes are found in this facies. We interpret this Facies B to represent a
deeper water inner shelf environment inhabited by a diverse fauna of
epifaunal and infaunal mollusks.
Facies C) Fine quartz sands that include increasing
numbers of glauconite grains (average 25% by weight – Fig. 6) and a decrease
in carbonaceous matter. The sediments
are extensively bioturbated with dense burrows of Thallassinoides. Also
present are phosphatic grains.
Macrofossils in this interval include gryphaeid oysters, pectens and
common belemnites. The contact between
Facies B and Facies C appears to be erosional and is marked by irregular
sandy blobs of uncertain origin, phosphatic pebbles, belemnite guards, and
large, branching burrows (Thallasinoides)
that penetrate vertically, piping dark, glauconitic sands from Facies C down
into the lighter mud-rich sediments of Facies B. This contact appears to mark a significant
decrease in the rate of sediment influx combined with current winnowing of
the upper surface of Facies B. Similar
contacts have been observed in Tertiary sediments on the New
Jersey slope, where they are interpreted to be
current eroded firmgrounds (Savrda et al., 2001). The sandy blobs may be the remnants of a
lag layer of quartz sand produced by winnowing, possibly concentrated into
horizontal burrows. We interpret
Facies C to represent a transitional environment between inner and outer
Facies D) Glauconite sands
(average 90% by weight – Fig. 6) with little to no detrital quartz grains.
The sediments are extensively bioturbated with dense burrows of Thallassinoides. This facies includes two shell-rich
intervals with abundant gryphaeid oysters.
The lower interval is dominated by articulated individuals of the
oyster Exogyra costata and contains
few other species. The upper
fossiliferous interval is more diverse and dominated by the oysters Pycnodonte mutabilis and Agerostrea mesenterica, with an
accessory fauna of Choristothyris brachiopods
and small pectens. Benthic and
planktic foraminifera are very abundant in the upper shell bed. Also common are the spines from burrowing
echinoids, although echinoid body fossils are not found. Of the large
oysters, almost 100% show evidence of biocorrosion, primarily in the form of
clionid borings, but also present are borings attributable to lithophagid
bivalves, acrothoracican barnacles, and polychaete annelids. Encrusting organisms are also common and
include several species of bryozoa, serpulid annelids, and small
oysters. Many large oyster valves are
almost completely biodegraded and some show evidence of having remained
partially buried for extended periods of time. Most bivalved specimens are disarticulated,
although approximately even valve ratios are present in samples. These observations suggest a benthic
environment undisturbed by wave activity or pulses of substantial sediment
input, where shells remained exposed on the sediment surface for long periods
of time or became partly buried by the activities of burrowing
organisms. The upper shell bed is a
backlap shellbed deposited near the position of the maximum flooding surface
(MFS) (Bennington et al., 1999).
Modern sediments composed almost exclusively of glauconite grains are
found in current swept, open marine environments of the middle to outer shelf
at depths greater than 60 m, with the optimum depth of glauconite formation
found to be approximately 200 m near the top of the continental slope (Odin
and Fullagar, 1988).
Facies E) Similar to facies
D but with increasing amounts of very fine quartz sand, showing the
transition to the overlying Red Bank Formation.
Figure 5. Summary diagram of the Navesink Formation
at the Big Brook and Poricy Brook localities.
Figure 6. Percentage of coarse
to fine glauconite grains by weight in sediments from different facies in the
Navesink Formation at Big Brook, New
data point is the mean of separate runs on three splits from a single
sample. 95% confidence intervals
around each value are +/-
4% or less for all samples.
Brief Descriptions of the Field Trip Localities
Stop #1, Poricy Brook
Park is located in Monmouth
County, NJ on the Middletown-Lincroft
Road / Hwy 50 (Fig. 7). Fossil collecting is permitted within the
rules stipulated by the park.
Sediments and Fossils
Figure 7. Map showing location of Poricy Brook
uppermost section of the Navesink (Facies D – Fig. 5) is exposed at Poricy
Brook. The upper shell bed is exposed
at stream level and large specimens of Pycnodonte
can be seen weathering out of the clayey glauconitic sands. Careful disaggregation of the shell bed
sediments will reveal Agerostrea
, Exogyra, and the brachiopod
Choristothyris. Shell bed sediments also contain an abundant microfauna which can be extracted by soaking
the sediment in household bleach for several days and then washing through a
fine mesh to remove the clays. Careful
examination of specimens of Pycnodonte
will show that many contain faint red bands of original coloration preserved
in the shell. In addition, most Pycnodonte record evidence of repeated
predation attempts shown as irregular disruptions in the growth lines in the
shell and displacements of the preserved color bands (Bennington,
2002; Bennington et al., 2000).
Optional Stop #2, Big Brook at Hillsdale
The Navesink Formation is
exposed in cut banks along Big Brook in Monmouth County,
NJ and can be accessed from the Hillsdale
Road entrance to the Big Brook Nature Preserve
(Fig. 8). Fossil collecting is
permitted within the rules stipulated by the preserve. Walk upstream from the
bridge on Hillsdale Road
to the first large cut bank.
Sediments and Fossils
section exposes the middle interval of the Navesink Formation, from the top
of Facies B at stream level to midway through Facies D (Fig. 5). The contact between Facies B and C can be
clearly seen as a break in the slope of the cut bank wall about 30 cm from
stream level. Belemnite guards are
easy to find in the sediments directly above the contact. About midway up the cut bank wall is the
lower shell layer containing articulated specimens of Exogyra costata. The upper
shell bed is exposed near the top of the slope downstream from the bridge.
Figure 8. Map showing location of Big Brook Navesink
Stop #3, Big Brook at Boundary
The Navesink Formation is
exposed in cut banks along Big Brook in Monmouth County,
NJ and can be accessed from the bridge at
Boundary Road (Fig.
8). Fossil collecting is permitted
within the rules stipulated by the Big Brook Preserve. Walk downstream from the bridge on Boundary
Road observing the sediments exposed in the cut
banks. Do not go upstream of the
bridge – this reach is private property and the landowner is hostile toward
Sediments and Fossils
downstream from the bridge, one can observe Facies A through Facies D (Fig.
5) in various locations along the stream banks. At stream level the callianassid burrows (Ophiomorpha) typical of Facies A
weather out of the sediment in relief and their branching structure can be
observed. Just above eye level the
contact between Facies B and C is marked by a horizon of light, sandy
blobs. Climbing the vegetated slope of
a large slump at the first large cut bank downstream of the bridge allows
access to the upper shell bed, although it may be covered by loose sediment. Although the fossiliferous lag that marks
the sequence boundary at the base of the Navesink is below stream level at
this location, weathering of this horizon farther upstream creates a steady
supply of vertebrate fossils that are washed downstream. Sieving the stream gravels in the
downstream vicinity of the bridge will produce a variety of shark teeth, as
well as fish teeth and the occasional bone or tooth fragment from a marine
A., Slattery, W., and Chamberlain, J. A. Jr. (1996) Reworked Campanian and
Maastrichtian macrofossils in a sequence bounding, transgressive lag deposit,
Monmouth County, New Jersey, Northeastern Geology and Environmental Sciences,
v.18, p. 243-252.
J B. (2002) Cretaceous oysters on the half-shell: a record of durophagous
predation preserved in Pycnodonte
convexa. Geological Society of America,
Abstracts with Programs, v. 34 (6): 541.
J B., Bonelli, J., Chandler, J.,
and Selss, M. (1999). Paleoecological evidence for the formation of a backlap
shell bed during maximum flooding, Upper Cretaceous Navesink formation, New
Geological Society of America,
Abstracts with Programs, v. 31 (7): A468.
J B., Selss, M., and Vinnik, A. (2000). Original color banding preserved in the
Cretaceous oyster Pycnodonte convexa
records repeated disruption to shell growth, possibly related to episodes of
predation. Geological Society of America,
Abstracts with Programs, v. 32 (7): A371.
and Bennington, J B. (2000)
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formation, central New Jersey:
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and northern Delmarva Peninsula, Delaware and Maryland, U.S. Geological
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Big Brook: Upper Cretaceous Geology and Paleontology
Erich Rose, ed.
Spring Field Trip, June
For additional information on identifying Navesink
The Big Brook Identification Page