Documentation of the SantonianCampanian and Austinian-Tayloran 

Stage Boundaries in Mississippi 

and Alabama Using Calcareous 

Microfossils 

U.S. GEOLOGICAL SURVEY BULLETIN 1884 
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Documentation of the SantonianCampanian and Austinian-Tayloran 

Stage Boundaries in Mississippi 

and Alabama Using Calcareous 

Microfossils 

By HARRY J. DOWSETT 

U.S. GEOLOGICAL SURVEY BULLETIN 1884 
DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, Jr., Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

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UNITED STATES GOVERNMENT PRINTING OFFICE: 1989 

For sale by the Books and Open-File Reports Section 

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Library of Congress Cataloging in Publication Data 

Dowsett, Harry J. 

Documentation of the Santonian-Campanian and Austinian-Tayloran stage 

boundaries in Mississippi and Alabama using calcareous microfossils I 

Harry J. Dowsett. 

p. em. -(U.S. Geological Survey bulletin : 1884) 

Bibliography: p. 

Supt. of Docs. no. I 19.3 : 1884 

1. Stratigraphic correlation-Mississippi. 2. Stratigraphic correlationAlabama. 3. Paleontology, Stratigraphic-Cretaceous. 4. Paleontology, 

Stratigraphic-Mississippi. 5. Paleontology, Stratigraphic-Alabama. 

6. Foraminifera, Fossil-Mississippi. 7. Foraminifera, Fossil-Alabama. 

8. Ostracoda, Fossil-Mississippi. 9. Ostracoda, Fossil-Alabama. 

10. Plankton, Fossil-Mississippi. 11. Plankton, Fossil-Alabama. 

I. Title. II. Series. 

QE75.B9 no. 1884 [QE652.55.U6] 557.3 s-dc20 89-600080 

[551.7'09762] Cl p 
Documentation of the Santonian-Campanian and 

Austinian-Tayloran Stage Boundaries in Mississippi 

and Alabama Using Calcareous Microfossils 

By Harry J. Dowsett 

Abstract 

Identification of foraminifers, calcareous nannofossils, and ostracodes in samples from the Upper Cretaceous Eutaw, Mooreville, and Demopolis Formations of 

Mississippi and Alabama allows correlations between the 

standard European and provincial Gulf Coast Stages. The 

Austinian-Tayloran boundary, represented by a sedimentary hiatus in Texas and Arkansas, is within the Mooreville 

Formation of the eastern Gulf Coast. The SantonianCampanian boundary is within the Eutaw Formation of 

Mississippi and the lower Mooreville Formation of central 

Alabama. The Arcola Limestone Member of the Mooreville 

Formation, previously used as a marker bed for the 

Austinian-Tayloran boundary in the eastern Gulf Coastal 

Plain, lies well within the Tayloran Stage and appears to be 

time transgressive. 

INTRODUCTION 

Purpose and Scope 

The Austinian-Tayloran provincial Stage boundary of 

the U.S. Gulf Coast has been considered correlative with 

the Santonian-Campanian Stage boundary; however, this 

has not been universally accepted (Young, 1963; Hazel, 

1977). The Upper Cretaceous Eutaw Formation and Mooreville and Demopolis Formations of the Selma Group of 

Mississippi and Alabama represent an ideal test for documenting both the Santonian-Campanian and the provincial 

Austinian-Tayloran Stage boundaries in the eastern Mississippi embayment. 

In the east Texas embayment, the Austin ian-Tayloran 

Stage boundary usually occurs at a distinctive lithostratigraphic contact. The Austinian and Tayloran provincial 

Stages were formally defined by Murray (1961). Long 

before this, however, Gulf Coast geologists were attemptManuscript approved for publication February 10, 1989. 

ing correlations with the type Austin and Taylor units in 

Texas and were using the terms "Austin" and "Taylor" in a 

chronostratigraphic sense (Stephenson and Monroe, 1940; 

Stephenson and others, 1942; Cushman, 1946; Monroe, 

1946; Parks, 1958; Shaver, 1958). Based on previously 

published data, the chronostratigraphic position of the 

Austinian-Tayloran Stage boundary should fall within the 

Mooreville Formation of Mississippi and Alabama (Sohl, 

1964). 

The type sections of the Santonian and Campanian 

Stages were first described in 1856 and were named in 1857 

(Coquand, 1856, 1857). Microfossils from these stratotypes 

have been studied by many workers (e.g., Van Hinte, 1968; 

Goharian, 1971; Barr, 1972; Seronie-Vivien, 1972; Sissingh, 1977; Verbeek, 1977). The results of these studies 

have refined the limits of the stages and made correlations 

with other areas of the world more precise. Published data 

suggest that the Santonian-Campanian boundary falls within 

the Eutaw Formation of Mississippi and Alabama (Young, 

1963; Smith, 1975; Russell and others, 1982). This interpretation needs more complete documentation based on 

detailed sampling. About 50 samples from three outcrop 

localities and two cores (fig. 1) were examined for the 

purpose of documenting both the Santonian-Campanian and 

Austin ian-Tayloran Stage boundaries by means of calcareous nannoplankton, foraminifers, and ostracodes. 

Acknowledgments 

I appreciate the thoughtful reviews of W. V. Sliter, 

Page Valentine, N.F. Sohl, and J.E. Hazel. I thank N.F. 

Sohl, J.E. Hazel, and C.C. Smith for helpful discussions 

regarding the Mesozoic stratigraphy of the Gulf Coastal 

Plain. 

STRATIGRAPHY 

Three Upper Cretaceous marine formations have been 

investigated in the research area. They are, from oldest to 

Stratigraphy 
EXPLANATION I 

~ DEMOPOLIS FORMAT~N I ~MOOREVILLE FORM!TION 

• EUTAW FORMATION 

0 10 20 30 

I I I I 11 I I 

0 10 2-0 30 40 

40 Miles 

I 

I 

Kilometers 

I 

AREA OF ENLARGEMENT 

Figure 1. Sample sites and generalized distribution of Upper Cretaceous formations in Alabama and Mississippi. 

youngest, the Eutaw Formation, the Mooreville Formation, 

and the Demopolis Formation. The geographic and stratigraphic distribution of the Eutaw, Mooreville, and Demopolis Formations is shown in figures 1 and 2. The stratigraphic distribution of samples analyzed and an idealized 

lithology of the localities investigated are shown in figure 

5-7. 

Eutaw Formation 

The Eutaw Formation is separated into lower "typical" beds and the upper Tombigbee Sand Member. The 

lower unit is campo ed of glauconitic fine- to mediumgrained micaceous and interbedded with olive-gray to 

dark-gray clay lenses. Exposed surfaces weather to a deep 

2 Santonian-Campanian and Austinian-Tayloran Stage Boundaries in Miss. and Ala. Using Calcareous Microfossils 
MOLLUSCAN 

SPECIES 

RANGES 

NORTHEASTERN 

MISSISSIPPI 

(south - north) 

WESTERN ALABAMA 

OWL CREEK FORMATION PRAIRIE BLUFF CHALK 

~RIPLEY 

~MATION 

DEMOPOLIS 

FORMATION 

RIPLEY 

FORMATION 

BLUFFPORT MARL 

MEMBER -----

DEMOPOLIS 

FORMATION 

COFFEE 

SAND ARCOLA LIMESTONE MEMBER 

- ----

MOOREVILLE MOOREVILLE 

FORMATION FORMATION 

TOMBIGBEE SAND TOMBIGBEE SAND 

MEMBER MEMBER f----------

EUTAW 

FORMATION 

EUTAW 

FORMATION 

Figure 2. Generalized correlation chart for the eastern 

Gulf Coastal Plain, including selected molluscan ranges 

(modified after Sohl and Smith, 1980). 

reddish brown. Percolating ground waters deposit iron, 

forming sandy, oxidized concretions and masses of ferruginous sandstone. The typical Eutaw beds exhibit a high 

degree of crossbedding. Plant fragments and lignite are 

common. The sedimentological evidence indicates a highenergy, near-shore, shallow-water environment. Calcareous 

microfossils are rare to absent in these beds. In the study 

area, the Tombigbee Sand Member makes up the upper 30 

meters of the Eutaw Formation. This member is composed 

chiefly of massive bedded, glauconitic, calcareous sand. 

Indurated ledges and concretions are common. The type 

locality of the Tombigbee Sand Member is at Plymouth 

Bluff (fig. 1) on the Tombigbee River, Lowndes County, 

Miss. The upper 15 meters of the Tombigbee is particularly 

fossiliferous, and the type section at Plymouth Bluff is rich 

in marine calcareous microfossils. In the study area, the 

Tombigbee Sand Member appears to have been deposited in 

open marine sublittoral waters. The lower "typical" Eutaw 

beds have a maximum thickness of about 76 meters, but 

only the upper 4 meters were seen in the field area (DW-24, 

fig. 1). The entire Tombigbee Sand Member was observed 

during this study. 

Mooreville Formation 

The Mooreville Formation of the Selma Group is a 

dark- to blue-gray, slightly micaceous, chalky marl. An 

increase in sand content near the base of the formation is 

often referred to informally as the "transitional" Mooreville. 

Phosphate nodules and fish remains are present at the 

Mooreville-Tombigbee contact (Braunstein, 1959). 

Although the Mooreville Formation has been reported to 

rest disconformably on the Tombigbee Sand Member of the 

Eutaw Formation (Stephenson and Monroe, 1940; Monroe, 

1941; Newton and others, 1959), no physical evidence of a 

disconformity could be found during this study. If a hiatus 

is present, it represents less time than can be resolved with 

the present biostratigraphic framework. 

The Arcola Limestone Member is present at the top of 

the Mooreville Formation. The Arcola is a yellow to gray, 

highly bored, calcisphere packstone or wackestone (Russell 

and Keady, 1982). In the field area, the Arcola is exposed 

at the Gulf, Mobile, and Ohio railroad bridge on Tibbee 

Creek, Clay County, Miss., and at China Bluff, on the 

Tombigbee River, Sumter County, Ala.; it also occurs in 

the Alabama Power Company's South Selma Test Site 1 

core, Dallas County, Ala. (fig. 1). In Mississippi, the 

Arcola Limestone Member consists of two limestone beds, 

approximately 0.6 meter thick, separated by 0.75 meter of 

marl. To the east in Dallas County, Ala., the Arcola 

thickens to approximately 3 meters and consists of a number 

of limestone beds separated by marl units. Immediately 

above the Arcola, the basal Demopolis Formation contains 

phosphate nodules, phosphatic molds, and reworked cobbles of limestone. Stephenson and Monroe (1940) regarded 

this as a basal conglomerate and interpreted its base to be a 

diastem or possible unconformity. The entire Mooreville 

ranges in thickness from 53 meters in Clay County, Miss., 

to 122 meters in Dallas County, Ala. Calcareous microfossils are abundant throughout the Mooreville Formation. 

Microfossils are difficult to retrieve from the limestone beds 

of the Arcola, but they are abundant and well preserved in 

the marl between the indurated beds. 

Demopolis Formation 

The Demopolis Formation of the Selma Group rests 

conformably on the Arcola Limestone Member of the 

Mooreville Formation. The Demopolis Formation consists 

of medium- to light-bluish-gray chalk, impure chalk, and 

marl. The Demopolis Formation is divided into a lower, 

unnamed member and the upper Bluffport Marl Member. 

Only the lower part of the unnamed member was examined 

Stratigraphy 3 
in the present study. The lower 20 meters of the formation 

are lithologically similar to the Mooreville Formation, and 

are difficult to distinguish when the Arcola Limestone 

Member is covered. The lower, unnamed member consists 

of approximately 60 meters of marl overlain by 60 meters of 

chalk. The Bluffport Marl Member is approximately 15 

meters thick and has a greater clastic fraction than the 

conformably underlying chalks (Russell and Keady, 1982). 

The calcium carbonate content of the chalk ranges from 72 

to 90 percent; this fraction is made up of calcareous 

nannofossils and lesser amounts of foraminifers, mollusks, 

and other calcareous remains. The Demopolis Formation, 

like the underlying Mooreville Formation, contains an 

excellently preserved assemblage of foraminifers, nannofossils, and ostracodes. 

GULF COAST -EUROPEAN CORRELATIONS 

Molluscan faunal zones have been established in the 

chalks and marls of the Selma Group mainly on the basis of 

ranges of species of the ostreid Exogyra (fig. 2). The 

present study is restricted to the Exogyra ponderosa range 

zone, which extends from the Tombigbee Sand Member of 

the Eutaw Formation, underlying the Selma Group, to about 

31 meters below the top of the Demopolis Formation, 

frequently related to strata of latest Santonian through latest 

Campanian age (Stephenson and Monroe, 1940; Stephenson and others, 1942; Monroe, 1946; Keady, 1962; Copeland, 1968; Sohl and Smith, 1980; Russell and others, 

1982). 

Stephenson and Monroe ( 1940) listed the faunas 

present in the various Exogyra zones in Mississippi and 

attempted several informal correlations to the standard 

Texas and European Stages. The presence of the planktonic 

crinoid Marsupites americanus Springer and of members of 

the ammonite genus Muniericeras in the Tombigbee Sand 

Member was cited as evidence of a Santonian age. Forms 

closely related to Placenticeras guadalupae (Roemer) and 

Texanites texanus (Roemer), which are present in the upper 

Austin Group (Young, 1963), were also found by Stephenson and Monroe (1940). The presence of Mortoniceras in 

the lower part of the Selma Group indicated a late Austin 

age. The Diploschiza cretacea Zone, a short taxon range 

zone in the Demopolis Formation, was correlated with the 

Pecan Gap Formation of the Taylor Group in Texas. 

Stephenson and Monroe (1940, p. 243) summarized their 

findings by stating that "the basal beds of the Selma Chalk 

in Mississippi and Alabama are believed to be as old as the 

uppermost beds of the Austin Chalk of Texas; the part of the 

Selma that lies between these basal beds and the base of the 

Exogyra costata Zone correspond in age to the Taylor marl 

of Texas." 

Stephenson and others ( 1942) published a correlation 

chart of the outcropping Cretaceous formations of the 

Atlantic and Gulf Coastal Plains and Trans-Pecos Texas and 

stated that "the Taylor marl and its age equivalents in the 

Atlantic and Gulf Coastal Plains are co-extensive with all 

but the lowermost part of the Exogyra ponderosa Zone." 

These authors correlated the Austinian-Tayloran boundary 

to about the middle of the Mooreville Formation. Monroe 

(1946) changed the position of the Austinian-Tayloran 

boundary to coincide with the Mooreville-Demopolis contact. Monroe cited unpublished work by Applin and Braunstein that identified Tayloran foraminifers from the lower 

Demopolis and Austinian foraminifers from the Arcola as 

evidence justifying this change. Eargle (1950) claimed that 

the Mooreville foraminifers and ostracodes were abundant 

and generally similar to those found in the Austin Group of 

Texas. He cited the work of Higgs (1945) that documented 

Austinian and Tayloran species throughout the Mooreville 

in Montgomery County, Ala. A review of Higgs' thesis by 

the author showed that whereas species known to be present 

in the upper Austinian range throughout the Mooreville 

Formation, the diagnostic Austin species Vaginulina texana 

Cushman is restricted to the lower Mooreville. These data 

have been reproduced in the present study. In the subsurface, the top of the Mooreville is generally picked at the 

highest occurrence of V. texana (Braunstein, 1959). 

According to Braunstein, the Arcola Limestone Member 

marks the Austinian-Tayloran boundary. 

Little has been done to determine accurately the 

relative positions of the Santonian-Campanian and 

Austinian-Tayloran boundaries in the eastern Mississippi 

embayment. Seemingly for convenience, the two boundaries are drawn by some authors at the same stratigraphic 

level (Stephenson and others, 1942; Pessagno, 1967). The 

use of the Arcola as a boundary marker seems to be 

entrenched in the literature (Braunstein, 1959; Canis and 

Zullo, 1986). 

Several more recent studies have added valuable data 

to the Upper Cretaceous stratigraphy of the Gulf Coastal 

Plain. Masters (1970) studied the stratigraphic distribution 

of planktonic foraminifers in the· Selma Group of Alabama. 

He indicated that the Santonian-Campanian boundary 

occurred within the Mooreville Formation but did not relate 

his findings to the standard Texas section. Brouwers and 

Hazel (1978), using ostracodes, gave the Arcola Limestone 

Member a Tayloran age. More recently, Mancini and Smith 

(1982) provided a preliminary biostratigraphic framework 

for the Upper Cretaceous deposits of the lower Mississippi 

embayment in Tennessee and Mississippi. Using nannofossils and planktonic foraminifers, they related units to the 

standard European stages only, concluding that the 

Santonian-Campanian boundary was within the Tombigbee 

Sand Member of the Eutaw Formation. Ross and Maddocks 

(1983) and Chimene and Maddocks (1984) studied the 

distribution of ostracodes in the upper Austin and Taylor 

Groups in Texas. Their results confirm the biostratigraphic 

zonation produced by Hazel and Brouwers (1982), which is 

used in this study. 

4 Santonian-Campanian and Austinian-Tayloran Stage Boundaries in Miss. and Ala. Using Calcareous Microfossils 
Santonian-Campanian Boundary 

In 1856, Coquand described the Upper Cretaceous 

rocks of the Charente region, France, distinguishing several 

lithologic "formations" which have since gained worldwide 

acceptance as stage and age names (Van i-linte, 1965). 

Coquand designated the section at Aubeterre the stratotype 

for the Campanian, but did not clearly designate a stratotype 

for the Santonian. According to Van Hinte (1965), Coquand 

used a currently fragmented section along the road from 

Javresac to Saintes as a starting point for his investigation of 

the Santonian. Just where along the road the stratotype 

should be placed, and what the true limits of the Santonian 

are, remain in question. 

A standard for the Cretaceous System was presented 

by Muller and Schenck in 1943. The standard was built up 

by fitting together continuous, well-exposed sections in 

Europe; it was divided into series, stages, and zones on the 

basis of paleontological evidence. The basal Campanian 

ammonite zone is characterized by the first appearance of 

Diplacnoceras bidorsatum. An examination of the planktonic foraminifera contained in this zone shows that the first 

appearance of Globotruncanita elevata (Brotzen) closely 

approximates the first appearance of D. bidorsatum. Based 

on this evidence, the use of G. elevata as a marker species 

has found worldwide acceptance (Dalbiez, 1955; Pessagno, 

1967; Postuma, 1971; Sigal, 1977; Butt, 1981; Dowsett, 

J 984). A close look at the biostratigraphic position of the 

Santonian and Campanian stratotypes reveals a more complicated situation. The macrofossil zonation does not come 

directly from the stratotypes. No single group of macrofossils is present in all the stratotypes. Second-order correlations are required to correlate the macrofossil biozonations 

with the stratotypes, resulting in confusion (Van Hinte, 

1968; Barr, 1972; Seronie-Vivien, 1972; Verbeek, 1977). 

The Santonian and Campanian stratotypes contain foraminifers and calcareous nannofossils, however, and the nannofossils allow a first-order correlation of the stratotypes 

(Verbeek, 1977). As stated earlier, the exact location of the 

Santonian stratotype is uncertain. Verbeek (1977) examined 

several samples and identified a poorly preserved nannofossil flora belonging to his Zygodiscus spiralis Zone. This 

zone can be correlated with the Calculites obscurus nannofossil zone and the upper, but not uppermost, part of the 

Dicarinella asymetrica planktonic foraminiferal zone used 

here. The base of the Campanian stratotype is in the 

Ceratolithoides aculeus Zone, according to Verbeek 

(1977). This zone correlates with the lower, but not lowest, 

part of the G. elevata Zone (fig. 3). 

The placement of the Santonian-Campanian boundary 

at the first appearance of Globotruncanita elevata in light of 

the nannofossil evidence may or may not be accurate. Many 

calcareous nannofossil workers (Thierstein, 1976; Sissingh, 

J 977; Verbeek, 1977) place the boundary at the first 

appearance of Aspidolithus parcus (Stradner), which is 

most probably in the gap between the stratotypes of both 

stages. In the present study, the first appearance of A. 

parcus is used as the Santonian-Campanian boundary 

marker. 

Austin ian-Tayloran Boundary 

The term "Gulf series" was first used by Hill ( 1887) 

to define the youngest ·cretaceous in the Gulf Coastal 

province. The Gulf series is currently applied to the upper 

part of the marine Cretaceous rocks in the Gulf Coastal 

province. The Gulf series is commonly divided into five 

stages, from youngest to oldest, as follows: Navarroan, 

Tayloran, Austinian, Eaglefordian, and Woodbinian. 

Rocks now belonging to the Austin Group were 

originally described by Shumard (1860) as the Austin 

limestone, a fossiliferous, cream-colored, bluish, earthy 

limestone that had an exposure of approximately 100 feet 

(30 meters) in the vicinity of Austin, Travis County, Tex. In 

1937, Stephenson redescribed the Austin chalk and 

assigned a thickness of 420 feet (128 meters) in the type 

area. He noted that the relation of faunal zones in the upper 

part of the Austin chalk to the top of the chalk indicated a 

regional unconformity of varying magnitude between the 

Austin chalk and Taylor marl. He attributed this to unequal 

erosion at the top of the Austin chalk and differential 

warping in early Taylor time. The Taylor marl, or Exogyra 

ponderosa marl, now belonging to the Taylor Group was 

first described by Hill (1892) as a chalky clay 1,200 feet 

(366 meters) thick, characterized by E. ponderosa. 

In the east Texas embayment there is generally a 

distinctive contact, with a hiatus, generally of short duration, between the upper Austinian and lower Tayloran 

lithostratigraphic units (Hazel and Brouwers, 1982; Young, 

1982). The lithostratigraphic sequence for the Austin and 

Taylor Groups is shown in figure 4. By examining the 

published literature on macrofossils, foraminifers, calcareous nannofossils, and ostracodes, several first and last 

appearances come to light that closely approximate the 

Austin ian-Tayloran Stage boundary. There are no planktonic foraminifers with easily identifiable datums at the 

Austinian-Tayloran boundary. Pessagno's (1967) monograph is difficult to follow on this point because the 

Santonian-Campanian and Austinian-Tayloran boundaries 

are drawn at the same level. Several species first appear or 

disappear at the Austin ian-Tayloran boundary, but more 

recent studies have extended the ranges of these taxa. A 

recent study of the boundary by Marks and Starn (1983) 

suggests no significant planktonic faunal changes. 

One benthic foraminifer, Vaginulina texana Cushman, has a last appearance at the Austinian-Tayloran 

boundary (Cushman, 1946; Braunstein, 1959). V. texana 

has been used extensively by researchers over the last 40 

years to identify the Austinian-Tayloran boundary in both 

subsurface and outcrop sections. 

Gulf Coast-European Correlations 5 
STAGES 

IMPORTANT 

z 

<( 

PLANKTONIC CALCAREOUS OSTRACODE CALCAREOUS 

w FORAMINIFERAL I- NANNOFOSIL ZONATION MICROFOSSIL a.. u_C/) ZONATION ZONATION 0 

0 .....J<( DATUMS 

a: =>0 ' 

:::> C)() w ( 

Quad rum 

I ~issinghi ..&.. Quadrum sissinghi 

Ceratolithoides 

z z aculeus 

<( <( Globotruncanita Ascetoleberis 

a: z 0 elevata plummeri ..&.. Ceratolithoides <( ..J 

Q. > aculeus 

:E <( 

.... Calculites 

<( ova/is Ascetoleberis plummeri 0 4 _ Marthasterites 

....a..;..., furcatus 

A.latacythere 

m 

-r cheethami 

Aspidolithus Dicarinella asymetrica 

pare us Alatacythere 

cheethami 

z 

<( Dicarinella £Aspidolithus parcus z .... i= asymetrica 

z en ..&.. ---Aiatacythere 

<( ::;) 

Calculites Veenia \ cheethami 

en <( 

obscurus quadrialira Globotruncanita elevata 

Figure 3. Approximate correlation of biostratigraphic zonations, important fossil events, and European and provincial 

stages discussed in the text. 

Several calcareous nannofossil datums fall on either 

side of the boundary, giving a reasonable approximation of 

its location. Aspidolithus parcus, the nannofossil marker for 

the Santonian-Campanian boundary, makes its first appearance in the upper Austinian (Leshner, 1983). The last 

appearance of Marthasterites furcatus (Deflandre) occurs in 

the lower Tayloran (Gartner, 1968; Bukry, 1969; Barrier, 

1980). Both datums have been well established in the 

Coastal Plain and bracket the boundary. 

A review of the stratigraphic distribution of Cretaceous ostracodes of the Atlantic and Gulf Coastal Plains 

shows several species with important first and last appearances in the Austinian-Tayloran boundary interval (Hazel 

and Brouwers, 1982). Ascetoleberis plummeri (Israelsky) 

and other species of this genus make their first appearance 

at the boundary, making it relatively easy to distinguish. 

Alatacythere cheethami (Hazel and Paulson) and Brachycythere durhami Hazel and Paulson have last appearances 

either just below or at the boundary. Haplocytheridea 

insolita has a first appearance in the lower part of the A. 

plummeri Zone (Hazel and Brouwers, 1982). 

By integrating the foraminifers, ostracodes, and calcareous nannofossils, several reliable and easily identifiable 

datums can be used to document the Austinian-Tayloran 

boundary (see also fig. 3). 

MICROFOSSIL ZONATIONS 

Planktonic Foraminiferal Zonation 

Zonations of the Upper Cretaceous based on planktonic foraminifers have been proposed by Bolli (1966), 

Pessagno (1967), Postuma (1971), Sigal (1977), Van Hinte 

(1976), Wonders (1980), and Caron (1985). The planktonic 

foraminiferal zonation presented here (fig. 3) follows 

closely the zonation of Caron (1985). 

Dicarinella asymetrica Zone: The base is defined by 

the first appearance datum of D. asymetrica (Sigal, 1952). 

6 Santonian-Campanian and Austinian-Tayloran Stage Boundaries in Miss. and Ala. Using Calcareous Microfossils 
CENTRAL 

TEXAS 

PECAN GAP 

FORMATION 

SPRINKLE 

FORMATION 

BURDITI 

FORMATION 

DESSAU 

FORMATION 

NORTHEAST 

TEXAS 

WOLFE CITY 

FORMATION 

OZAN 

FORMATION 

ARKANSAS 

OZAN 

FORMATION 

MISSISSIPPIALABAMA 

DEMOPOLIS 

FORMATION 

MOOREVILLE 

FORMATION 

FigUJ·e 4. Generalized correlation chart for the east 

Texas embayment and the eastern Gulf Coastal Plain 

(modified after Hazel and Brouwers, 1982). 

The top is defined by the last appearance of D. asymetrica 

(Sigal, 1952). The D. asymetrica Zone was first used by 

Postuma (1971). His Globotruncana concavata carinata 

Zone, by synonymy, is equivalent to the D. asymetrica 

Zone used here. The D. asymetrica Zone includes the 

Globotruncanita elevata-Dicarinella asymetrica concurrent 

range zone concept of many authors (Masters, 1970, 1977; 

Van Hinte, 1976; Wonders, 1980; Dowsett, 1984). 

Globotruncanita elevata Zone: The base is defined by 

the last appearance of Dicarinella asymetrica (Sigal, 1952). 

The top is defined by the first appearance of Globotruncanita calcarata Cushman, 1927. The G. elevata Zone was 

first used by Dalbiez (1955). Although not formally 

defined, his Globotruncana elevata faunizone can be interpreted to begin with the first appearance of G. elevata and 

end with the first appearance of G. calcarata. As it is used 

here, the G. elevata Zone was originally proposed by 

Postuma (1971). The author follows the example of many 

workers (e.g., Postuma, 1971; Premoli Silva and Boersma, 

1977; Sigal, 1977) in defining the top of the G. elevata 

Zone with the first occurrence of G. calcarata. Wonders 

(1980) defined the top of his Globotruncana elevata (=G. 

elevata) Zone as the first occurrence of Globotruncana 

ventricosa White. He stated (p. 53, 54), however, that G. 

ventricosa may be an immigrant to the western Mediterranean and therefore not useful for interregional correlation. 

Caron (1985) also terminates his G. elevata Zone with the 

first appearance of G. ventricosa. G. ventricosa has not 

traditionally been used in the Gulf Coast to mark the top of 

this zone (Caron, 1985) and is not used as a marker in this 

study. In a recent study (Dowsett, 1984), G. ventricosa was 

observed in both lower Campanian and uppev Santonian 

samples from a core in the northeastern Gulf of Mexico. 

During the present study, individuals of G. ventricosa have 

been observed chronostratigraphically below the level at 

which Wonders (1980) found the first G. ventricosa in 

North Africa. 

Calcareous Nannofossil Zonation 

Calcareous nannofossil zonations covering the 

Santonian-Campanian part of the Upper Cretaceous have 

been proposed by Cepek and Hay (1969, 1970), Bukry 

(1969), Bukry and Bramlette (1970), Manivit (1971, 1972), 

Roth and Thierstein (1972), Bukry (1973), Roth (1973), 

Thierstein (1976), Sissingh (1977), Perch-Nielsen (1979), 

and Stradner and Steinmetz (1984). The calcareous nannofossil zonation proposed by Sissingh ( 1977) is applicable to 

the Gulf Coast Upper Cretaceous and is used here (fig. 3). 

Calculites obscurus Zone (CC 17): The base is 

defined by the first appearance of C. obscurus (Deflandre, 

1959). The top is defined by the first appearance of 

Aspidolithus parcus (Stradner, 1963). The C. obscurus 

Zone was first used by Sissingh (1977). It is difficult to 

correlate the base of the C. obscurus Zone with other 

published nannofossil zonations because of the lack of 

agreement on the first occurrence of C. obscurus. Sissingh 

( 1977) indicated that the first occurrence of C. obscurus 

was correlative with the Santonian-Campanian boundary 

and with the base of the foraminiferal Globotruncana 

elevata Zone of Postuma (1971). Thierstein (1976) placed 

the initial appearance of Tetralithus obscurus (=C. obscurus) within the Santonian. Citing a poorly understood 

variation in the genus Calculites, Verbeek ( 1977) placed the 

first occurrence of the C. obscurus group in the middle 

Turonian. As used in the present study, the C. obscurus 

Zone correlates at least in part with the Zygodiscus spiralis 

Zone of Verbeek ( 1977) and represents the uppermost 

Santonian. 

Aspidolithus parcus Zone (CC18): The base is 

defined by the first occurrence of A. parcus (Stradner, 

1963). The top is defined by the last occurrence of Marthasterites furcatus (Deflandre, 1954). The A. parcus 

( = Broinsonia parca) Zone was first used by Sissingh 

(1977). Bukry and Bramlette (1970) described an Eiffellithus augustus Zone as the interval between the first 

occurrence of A. parcus and the extinction level of E. 

augustus. The A. parcus Zone as used in the present study 

correlates with the lower portion of the E. augustus Zone of 

Bukry and Bramlette (1970). The Broinsonia parca Zones 

ofBukry (1973) and Roth (1973) are partial range zones and 

occur stratigraphically higher than the A. parcus Zone used 

here. The A. parcus Zone is equivalent to the lower half of 

the B. parca Zone of Verbeek (1977). Sissingh (1977) and 

Perch-Nielsen (1979) divide this zone into three parts on the 

basis of first occurrences of Bukryaster hayi and Ceratolithoides verbeekii. The A. pare us Zone represents the 

lowermost Campanian. 

Calculites ovalis Zone (CC19): The base is defined by the last occurrence of Marthasterites furcatus 

Microfossil Zonations 7 
(Deflandre, 1954). The top is defined by the first occurrence of Ceratolithoides aculeus (Stradner, 1961). The C. 

ovalis Zone was first used by Sissingh (1977). S.issingh 

(1977) and Perch-Nielsen (1979) divide this zon~ into two 

parts on the basis of the last occurrence of Bukryas(er hayi. 

Ceratolithoides aculeus Zone (CC20): The base is 

defined by the first occurrence o( C. aculeus (Stradner, 

1961). The top is defined by the 1

first occurrence of 

Quadrum sissinghi Perch-Nielsen, 1984 ( = Tetralitli11s nitidus) Martini (1961). Cepek and Hay (1969) originally 

defined the Tetralithus aculeus Zone. While their base is 

defined by the first occurrence of r: aculeus ( = C. 

aculeus), their top is defined by the first occurrence of 

Chiastozygus initialis. Sissingh emended the zone to its 

present definition in 1977. This zone is equivalent to the C. 

aculeus Zone of Verbeek ( 1977). 

Quadrum sissinghi Zone (CC21): The base is defined 

by the first occurrence of Q. sissinghi Perch-Nielsen, 1984. 

The top is defined by the first occurrence of Quadrum 

trifidum (Stradner, in Stradner and Papp, 1961). The Q. 

sissinghi ( = Tetralithus nitidus) Zone was first used by 

Sissingh in 1977. This zone is recognized by Verbeek 

(1977) and Perch-Nielsen (1979, 1985). 

Ostracode Zonation 

The ostracode zones used here (fig. 3), all of which 

are based on first occurrences, are those of Hazel and 

Brouwers (1982). 

Veenia quadrialira Zone: The base is defined by the 

first appearance of V. quadrialira (Swain, 1952). The top is 

defined by the first appearance of Alatacythere cheethami 

(Hazel and Paulson, 1964). 

Alatacythere cheethami Zone: The base is defined by 

the first appearance of A. cheethami (Hazel and Paulson, 

1964). The top is defined by the first appearance of 

Ascetoleberis plummeri (Israel sky, 1929). 

Ascetoleberis plummeri Zone: The base is defined by 

the first appearance of A. plummeri (Israel sky, 1929). The 

top is defined by the first appearance of Limburgina 

verricula (Butler and Jones, 1957). 

RESULTS 

The localities investigated during this study can be 

divided into several groups (sample localities are shown in 

fig. 1 and are further described in the appendix). The 

Plymouth Bluff, Tibbee Creek, and DW -24 sites form a 

composite section within the Eutaw, Mooreville, and 

Demopolis Formations in northeastern Mississippi. This 

section is hereafter referred to as the "Mississippi composite." The Selma core, located farther to the east on the 

Alabama River, also represents an interval within the Eutaw 

(Tombigbee Sand Member), Mooreville, and Demopolis 

Formations. The section at China Bluff on the Tombigbee 

River is situated geographically between the Selma core and 

t~e Mississippi composite (see also fig. 1). China Bluff 

exposes the upper Mooreville Formation, including the 

, Arcola Limestone Member. The stratigraphic occurrence of 

selected microfossils from these localities is shown in tables 

1-3. 

Selma Core 

The most complete section investigated during this 

study is at the Alabama Power Company South Selma Test 

Site 1, called the Selma core. Both the SantonianCampanian and Austinian-Tayloran boundaries can be documented using the three fossil groups previously discussed. 

The positions of samples and zonal assignments are shown 

in figure 5. The stratigraphic distribution of microfossils 

within the Selma core is given in table 1. 

The Santonian-Campanian boundary is placed at the 

first appearance of Aspidolithus pare us. As discussed earlier, this datum is accepted as the boundary marker by many 

workers. The first appearance of the nannofossil species A. 

parcus occurs stratigraphically above the first appearance of 

Globotruncanita elevata. Whether G. elevata or A. parcus 

is used to mark the boundary is unimportant. The integrated 

nannofossil and foraminiferal datums within the boundary 

interval in the Selma core fit well with the established 

literature. 

The . first appearance of Globotruncanita elevata 

occurs 143.20 meters below the surface in sample ALA 7. 

The Tombigbee Sand Member of the Eutaw Formation 

present in the Selma core, along with the lower 35 meters of 

the Mooreville Formation, is placed in the Dicarinella 

asymetrica Zone. The basal Campanian G. elevata Zone 

ranges between sample ALA 7 ( 143.20 meters) and the top 

of the studied portion of the core (50 meters). The last 

appearance of Sigalia deflaensis (Sigal) has been shown to 

occur within the concurrent range of G. elevata and D. 

asymetrica by many workers (Barr, 1972; Salaj, 1980; Butt, 

1981; Dowsett, 1984). Masters (1970), studying material 

from Alabama, identified the last appearance of S. deflaensis below the first appearance of G. elevata. In the Selma 

core, S. deflaensis was recovered from Santonian sediments 

only (samples ALA3, ALA31). 

Samples below ALAS are assigned to the Calculites 

obscurus Zone based on the presence of C. obscurus and the 

absence of Aspidolithus pare us. Marthasterites furcatus is 

present from the base of the core to a point 90 meters below 

the surface (ALA13). This datum marks the boundary 

between the A. pare us Zone below and the C. oval is Zone 

above. The C. ovalis Zone extends upward to sample 

ALA25, where the first appearance of Ceratolithoides 

aculeus marks the base of the C. aculeus Zone. This zone 

extends to the top of the section of core studied, encom8 Santonian-Campanian and Austinian-Tayloran Stage Boundaries in Miss. and Ala. Using Calcareous Microfossils 
STAGE 

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SELMA CORE 

. DEMOPOLIS 

FORMATION 

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50 

60 

70 

80 

90 

~MARL 

.LIMESTONE 

(l]BIOTURBATION 100 

.,..-r::,•==~:=:r:. ""~MEGA FOSSILS 

NO RECOVERY 

I 110 

STAGE 

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en 

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SELMA CORE 

TRANSITION 

'~'-;; "- .;:.:, ~ TOMBIGBEE SAND 

MEMBER 

EUTAW FORMATION 

120 

130 

140 

150 

160 

170 

180 

Figure 5. Stratigraphic summary of the Selma core. Arrows indicate position of samples used in this study (sampl e 

numbers preceded by ALA in text). 

passing the uppermost part of the Mooreville Formation , 

including the Arcola Limestone Member, and the lower 4.6 

meters of the Demopolis Formation . 

Small sample size resulted in patchy occurrences and 

unfilled ranges for many of the ostracode species. Hazel and 

Brouwers (1982) indicated that the boundary between the 

Veenia quadrialira and Alatacythere cheethami Zones 

approximates the first appearance of Globotruncanita elevata and the Santonian-Campanian boundary (fig. 3). However, J.E. Hazel (written commun., 1984), on the basis of 

new data, states that G. elevata first appears before A. 

cheethami. Hazel estimates the difference between the two 

datums to represent 1. 5 million years. In the present study , 

V. quadrialira is represented by one poorly preserved 

specimen that occurs 170 meters below the surface (sample 

ALA3). This is well within the Santonian as defined by both 

foraminifers and nannofossils. Veenia ozanana (lsraelsky) 

and Veenia ponderosana (lsraelsky) are present in many 

samples below the first appearance of G. elevata . Both 

ostracode species evolved early in the V. quadrialira Zone 

and are evidence that the lower portion of the Selma core 

can be no older than the V. quadriaLira Zone. A. cheethami 

has a single occurrence 134.9 meters below the surface 

(sample ALA9). A. cheethami is confined to the A. 

cheethami Zone. The 25-meter uncored section between 

samples ALA9 and ALA10 may explain there being no 

higher occurrences of this species. Brachycythere durhami 

normally last appears at or near the top of the A. cheethami 

Zone but was fo und no higher than sample ALA 7. Brachycythere acuminata (Hazel and Paulson) and Physocythere 

annulospinata (Hazel and Paulson) have first appearances 

in the lower part of the zone (Hazel and Brouwers, 1982). 

Both species first appear in sample ALA9 along with A. 

cheethami in the Selma core. Whereas the base of the A. 

cheethami Zone is a little higher than was expected from the 

literature , the simultaneous first occurrence of three species 

that appear early in the zone is here accepted as evidence for 

a close approximation of the chronostratigraphic position of 

Results 9 
Table 1. Microfossil occurrences in the Selma core 

[Numbers are ALA sample numbers in text. X, present; --, absent] 

1 2 30 3 31 4 5 6 7 8 9 10 11 12 13 15 17 18 20 21 23 25 26 28 29 

Ostracodes 

Alatacythere cheethami ----------- __ __ __ __ __ __ __ __ __ __ X ___________________________ _ 

Ascetoleberis plummeri ___________ ____________________________________ X X X X X X 

Ascetoleberis rugosissima ____________ ____________________________________ X X X X X X 

Brachycythere acuminata ____________ __________________ X ______ X ______ X ___________ _ 

Brachycythere durhami ----------- __ __ __ X __ X __ __ X _______________________________ _ 

Cytheropteron furcalatum __________ .;._ X __ X ____ X ____ X X X X X X __ X X _____________ _ 

Physocythere annulospinata ____ _:_ ____________________ X X X X X X X X 

Veenia ozanana ----------__ X __ X __ X __ X __ __ X X X __ X __ __ __ X ___________ _ 

Veenia ponderosana ______________ X ______ X __ X __ X __ ·x X X X __ X X X X X _______ _ 

Veenia quadrialira ____________ ______ X _________________________________________ _ 

Veenia spoori _____________ __________________________ .X ______ X ___________ _ 

Calcareous nannofossils 

Aspidolithus pare us---------__ __ __ __ __ __ __ __ __ X X X X X X X X X X X X X X X X 

Bukryaster hayi _______________ ______________________ X X X X X X X X X X X 

Calculites obscurus ________ __________ X X ____ X X __ X ____ X __ X X X __ X X X X 

Calculites ovalis ________ X __ X X __ X X X X X __ X __ X X X ____ X __ X X X X 

Ceratolithoides aculeus _________________________________________________ X X X X 

Marthasterites furcatus --------- X X X __ X X X X X X X X X X ___________________ _ 

Foraminifers 

Archaeoglobigerina cretacea _____ X X X X X X X X X X X X X X X X X X X X X X X X X 

Dicarinella asymetrica ________ X X X X X X X X X X _____________________________ _ 

Globotruncana area--------__ __ __ __ __ __ X __ __ X __ X X __ __ __ __ __ X ___________ _ 

Globotruncana linneiana _____________ __________________ X ______________ X X X X 

Globotruncana ventricosa __ X ________ X ____ X X X X X X X __ X X X X X X 

Globotruncanita elevata -======== __ __ __ __ __ __ __ __ X X __ X X X X X X X X X X X X X X 

Marginotruncana marginata _______ __ X __ X __ X X X X X X X X ____ X X X X X X X X X X 

Rosita fornicata __________ X X X X X X X X X X X X X X X X X X X X X X X X X 

Sigalia deflaensis _____________ ____ X X _______________________________________ _ 

Vaginulina texana X __ X ____ X X X X X _________________________ _ 

Ventilabrella glab;~1a-_-_-~-~~~~~ ______ X X X X X X X X X X _______________________ _ 

the base of the zone. The boundary between the A. 

cheethami and Ascetoleberis plummeri Zones is used by 

Hazel and Brouwers (1982) to mark the Austinian-Tayloran 

boundary. This boundary is marked by the first occurrence 

of A. plummeri and other members of the-genus Ascetoleberis. In Mississippi and Alabama the boundary has been 

projected to occur within the Mooreville Formation. The 

genus Ascetoleberis makes its first appearance 61.5 meters 

below the surface in the Selma core. By definition, this 

marks the base of the A. plummeri Zone. However, inspection of the nannofossil data in the Selma core compared 

with a U.S. Geological Survey model for the Upper 

Cretaceous (see Hazel and others, 1984) indicates that the 

first appearance of Ascetoleberis is later in the study area 

than in Texas and Arkansas. Cytheropteron furcalatum 

Alexander is thought to last occur at the base or in the early 

part of the A. plummeri Zone. In the Selma core, C. 

furcalatum is observed no higher than sample ALA18, 6 

meters below the first appearance of Ascetoleberis. 

The nannofossil species Marthasterites furcatus is 

last observed in lower Tayloran rocks in Texas and Arkansas (Barrier, 1980). In the Selma core, M. furcatus last 

appears in sample ALA 13, 28.7 meters below the first 

appearance of Ascetoleberis. As mentioned in a previous 

section, the last appearance of the benthic foraminifer 

Vaginulina texana has been used extensively to mark the 

Austin ian-Tayloran boundary in the Gulf Coast (Braunstein, 1959). As with the ostracodes, the small sample size 

may not have allowed detection of the true range of V. 

texana in the Selma core. V. texana is last observed in 

sample ALA 10, 110. 8 meters below the surface. The 

evidence presented by the last appearances of 

Cytheropteron furcalatum, M. furcatus, and V. texana 

suggests that the Austinian-Tayloran boundary lies below 

the first appearance of Ascetoleberis plummeri in the Selma 

core. The boundary probably lies between the last appearance of V. texana and M. furcatus and is tentatively placed 

between samples ALA10 and ALA13, approximately 

100 ± 10 meters below the surface and 36 meters above the 

Santonian-Campanian boundary. It is difficult to explain the 

sudden abundant appearance of both A. plummeri and 

Ascetoleberis rugosissima (Alexander) in terms of improper 

sample size. It is possible that the section between the single 

occurrence of Alatacythere cheethami and last appearance 

of V. texana and the first appearance of A. plummeri 

represents the amount of time missing at the Austin-Taylor 

contact in the western Gulf Coastal Plain. However, the top 

of M. furcatus indicates an early Tayloran age. Therefore, 

the 28.7 meters between the last appearance of M. furcatus 

and first appearance of A. plummeri must be explained 

10 Santonian-Campanian and Austinian-Tayloran Stage Boundaries in Miss. and Ala. Using Calcareous Microfossils 
Table 2. Microfossil occurrences at China Bluff 

[Numbers are ALA sample numbers in text. X, present; --, absent] 

49 48 47 46 45 44 68 69 

Ostracodes 

Alatacythere chuthami X X ___________ _ 

Ascetoleberis plummeri~=~~~-~~~-- ____________ X 

Brachycythere acuminata _________ X X ____ _______ _ 

Cytheropteron furcalatum ______ X X ______ X ___ _ 

Physocythere ann.ulospinata ______ ________ _ ___ X 

Veenia ozanana ________ X X X X X X X 

Veenia ponderosana -------__ X -- X X X 

Veenia spoori ________ X -- X X X 

Calcareous nannofossils 

Aspidolithus pare us--------- X X X X X X X X 

Bulcryaste r hayi _________ X X X X X X 

Calculites obscurus X X X X X X X ------ Calculi res oval is X X X X X X X X --------- Marthasterites furcatus _______ X X X X -- -- -- --

Foraminifers 

Archaeoglobigerin.a cretacea ----- X X X X X X X X 

Globotru1lcana area X X X X X X X ------- Globotruncana linneiana X X X X X - -------- Globotru1lcana ventricosa X X X ----- Globotruncanita elevata X X X X X X X ------- Marginotruncana marg inata -------· ____ X X X X 

Rosita fornicata __________ X X X X X X X 

Ve1ltilabre lla glabrata ______ X X X X X 

some other way . Alternatively, the genus Ascetoleberis may 

have migrated eastward to the Alabama area during early 

Tayloran time, explaining its first appearance so high in the 

section (J.E. Hazel, personal commun., 1983). Further 

study of the first appearance of Ascetoleberis with respect to 

the calcareous nannofossil datums and magnetostratigraphy 

is necessary to resolve this issue . 

China Bluff 

The section investigated at China Bluff traddles the 

Austin ian-Tayloran boundary and is placed entirely in the 

early Campanian . The stratigraphic distribution of microfossils from China Bluff is given in table 2. The position of 

samples and zonal assignments in the China Bluff section 

are shown in fig ure 6. The presence of Globotruncanita 

elevata, and the absence of both Dicarinella asymetrica and 

Globotruncanita calcarata in all samples, place the China 

Bluff locality entirely in the G. elevata Zone , which is 

Campanian in age . The presence of the nannofossil species 

Aspidolithus parcus in all samples is additional evidence for 

the section being no older than early Campanian. 

The last appearance of Marthasterites furcatus 9. 1 

meters above the base of the exposure indicates an early 

Tayloran age and defines the boundary between the Aspidolithus parcus and Calculites ovalis Zones. Samples 

ALA49-ALA46 are placed in the A . parcus Zone . The part 

of the section above sample ALA46 is assigned to the C. 

ovalis Zone . Sissingh (1977) used the last appearance of 

Bukryaster hayi to subdivide the C. ovalis Zone. Although 

this datum does not show up consistently in the material 

studied , it can be used to subdivide the C. ovalis Zone 

above and below sample ALA44 at China Bluff. 

STAGE 

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CHINA BLUFF SECTION 

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COVERED 

INTERVAL 

MOOREVILLE 

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METERS 

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[ill BIOTURBATION 

Figure 6. Stratigraphic summary of the China Bluff locality. Arrows indicate position of samples used in this study 

(sample numbers preceded by ALA in text). 

The presence of Alatacythere cheethami and 

Cytheropteron furcalatum in the lowest samples at China 

Bluff indicates a late Austinian age . Ascetoleberis plummeri 

first appears near the top of the section. As in the Selma 

core, this occurrence is anomalously hi gh and is best 

explained by a migration from the west. Vaginulina texana , 

the foraminiferal Austinian-Tayloran boundary marker, is 

not pre ent at China Bluff. 

Mississippi Composite 

By combining the occurrence data from Tibbee 

Creek , Plymouth Bluff, and the DW-24 core (table 3), a 

composite section for northeastern Mississippi can be 

formed (fig. 7). Approximately 2.4 meters of section is 

missing between the top of the DW-24 core and the base of 

the Plymouth Bluff section (fig. 7). Information from well 

logs in the area indicates that the Mooreville Formation is 

approximately 46 meters thick. Approximately 40 meters of 

section is missing between the base of the Tibbee Creek 

section and the top of Plymouth Bluff; therefore, several 

supplementary samples from within this gap (from a section 

downstream from the Tibbee Creek locality) were analyzed 

to provide better control . 

Results 11 
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MISSISSIPPI COMPOSITE SECTION 

-Y- -Y--Y--Y67 -7 f f • • **• DEMOPOLIS 

~ -7; f • • f • • • FORMATION 

66 -7 * ~~ _L,/(~ 65 ~ ..o...r- • ..o...r- ARCOLA LI MESTONE 

64 ~ ·~·~4 ~ \ MEMBER 

I' S _L, ( f \L..L MOOREVILLE 

63 ~-~Y-~!(1• FORMAT:ON 

40 m gap 

COVERE D 

-Y- -Y- -Y- 43 ~ • I' -Y- ¥ • 

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51 ~ • • • 

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MOOREVILLE 

FORMATION 

TOMBIGBE E 

SAND 

MEMBER 

EUTAW 

FORMATION 

TOMBIGBEE 

SAND 

MEMBER 

EUTAW 

FORMATION 

53~====~~-1 --------

~--== ~ 

- 54~~-

EUTAW 

FORMATION 

TIBBEE 

CREEK 

10 -

5 -

0 -

METERS 

PLYMOUTH 

BLUFF 

DW-24 

CORE 

~~~CHALK 

D s AND 

1: I MARL 

~ CLAY 

ITill BIOTURBATION 

~ MEGAFOSSILS 

PT-1 CALCAREOUS 

~SANDSTON E 

Figure 7. Stratigraphic summary of the Tibbee Creek and Plymouth Bluff localities and DW-24 core. Arrows 

indicate position of samples used in this study (sample numbers preceded by MIS in text). 

12 Santonian-Campanian and Austinian-Tayloran Stage Boundaries in Miss. and Ala. Using Calcareous Microfossils 
Table 3. Microfossil occurrences in the Mississippi composite 

[Numbers are MIS sample numbers in text. X, present; --, absent] 

DW-24 Core lPlymouth Bluff lTibbee Creek 

54 53 52 51 50 37 38 39 40 41 42 43 63 64 65 66 67 

Ostracodes 

Ascetoleberis plummeri _________ ____________________________ X X X 

Ascetoleberis rugosissima ________ __________________________ X X X 

Physocythere annulospinata _______ ____________ X __ X __ X X X X X X X 

Veenia ozanana ____________ ______ X X X X X __ X X X X X X X 

Veenia ponderosana X X X X 

Veenia spoori ---------== == == == == __ == __ == == __ ==-X-- -X X 

Calcareous nannofossils 

Aspidolithus pare us_________ __ __ __ __ __ __ __ __ __ X X X X X X X 

Bukryaster hayi X X X 

Calculites obscu-;;;---------- ---X -X -X -X -X -X -X X -X -X X X X X X 

Calculites ova/is X X X X X X X X X X X X X X 

Marthasterites furcatus ________ == == X X X X X X X X X ____ -------

Foraminifers 

Archaeoglobigerina cretacea X X X X X X X X X X X X X X X 

Dicarinella asymetrica -------- -- X X X X X X 

Globotruncana area ---------- -----X X X X __ -X -X -X -X -X -X 

Globotruncana linneiana_===--=~== == == == ________ X X ____ X X X X X 

Globotruncana ventricosa ______________________________ X X 

Globotruncanita elevata ------- X X X X X X X X X X X X 

Marginotruncana marginata ____ ~~== == ====-X X X __ X X X X X X X X 

Rosita fornicata X X X X X X X X X X X X X 

Vaginulina texa-;;;;---------- -- -X -X X X X X ______ X 

Ventilabrella glabrata~~=-=--~-=== == ______ X X __ X X X X -X -X -X -X -X 

DW-24 Core 

The lowest samples in the DW -24 core are in the 

lower unnamed unit of the Eutaw Formation, below the 

Tombigbee Sand Member, and contain no calcareous 

microfossils (samples MIS53 and MIS54). The presence of 

Calculites obscurus and the absence of Aspidolithus parcus 

in the upper 8.5 meters of the core indicate that the lower 

part of the Tombigbee Sand Member is assignable to the C. 

obscurus Zone, which suggests a Santonian age. Although 

poorly preserved, ostracodes are present throughout the 

Tombigbee in the DW -24 core; however, none gives a 

diagnostic age. The presence of Veenia ozanana indicates 

that the Tombigbee here can be no older than the Veenia 

quadrialira Zone. Foraminifers are rare and are not indicative of either a Santonian or a Campanian age. The absence 

of Globotruncanita elevata suggests a Santonian age but is 

most probably indicative of shallow water depth. Dicarinella asymetrica, present in the Tombigbee at Plymouth 

Bluff, is not found in the DW-24 core. All of the foraminifers observed are broken, incomplete specimens. The 

lower part of the Tombigbee represents a shallow marine 

environment probably unsuitable for globotruncanids. 

Plymouth Bluff 

The cooccurrence of Dicarinella asymetrica and Globotruncanita elevata in all but the highest sample at 

Plymouth Bluff places the lowest 19.8 meters of the 

Plymouth Bluff section in the uppermost part of the D. 

asymetrica Zone of earliest Campanian-latest Santonian 

age. The first appearance of Aspidolithus parcus in sample 

MIS42, 19.8 meters above the base of the section, defines 

the base of the A. parcus Zone and the SantonianCampanian boundary. The lower 19.8 meters of the Plymouth Bluff section are assigned to the Calculites obscurus 

Zone. The presence of Physocythere annulospinata 

throughout the Plymouth Bluff section suggests that the 

section may be no older than the Alatacythere cheethami 

Zone. No specimens of A. cheethami are found at Plymouth 

Bluff, but in supplementary samples in the area, A. 

cheethami was found to cooccur with G. elevata and D. 

asymetrica. Vaginulina texana is present throughout the 

DW-24 core and the entire Plymouth Bluff section. 

Tibbee Creek 

The upper Mooreville Formation, including the 

Arcola Limestone Member, and the basal Demopolis Formation exposed at Tibbee Creek are assigned to the Globotruncanita elevata Zone. The presence of Calculites 

ovalis (Stradner) and the absence of both Marthasterites 

furcatus and Ceratolithoides aculeus indicate the entire 

Tibbee Creek section to be assignable to the C. ovalis Zone. 

The exposed Mooreville, including the Arcola, is assigned 

to the lower half of the zone, and the Demopolis is assigned 

to the upper half. According to Mancini and Smith (1982), 

Results 13 
C. aculeus makes a first appearance 5. 3 meters above the 

Arcola in the Tibbee Creek area. The absence of both M. 

furcatus and Vaginulina texana at Tibbee Creek suggests a 

Tayloran age. Ascetoleberis plummeri and Ascetoleberis 

rugosissima first appear within the Arcola Limestone Member. This datum marks the base of the A. plummeri Zone of 

earliest Tayloran age. With respect to the foram and 

nannofossil datums, the base of the genus Ascetoleberis is 

appearing high in the section. Four supplementary samples 

were obtained from a 24.5-meter exposure that falls stratigraphically between the Plymouth Bluff and Tibbee Creek 

localities. Vaginulina texana has its last occurrence within 

this supplementary section, while M. furcatus is present 

throughout. Taking the thickness of the Mooreville Formation in this area to be about 46 meters, the AustinianTayloran boundary (based on the last appearance of V. 

texana) projects 21 ± 6 meters above the top of the Plymouth 

Bluff section. 

In the past the Arcola Limestone Member of the 

Mooreville Formation has been used to designate the 

Austinian-Tayloran boundary in the Gulf Coast (Braunstein, 1959). The data derived in this study indicate that this 

boundary is located well below the Arcola. The Arcola 

Limestone Member appears to be time transgressive. At the 

Tibbee Creek and China Bluff localities, the Arcola is 

placed in the upper half of the Calculites ovalis Zone. In the 

Selma core, the Arcola falls within the basal part of the 

Ceratolithoides aculeus Zone. The ostracode genus Ascetoleberis consistently first appears at the level of the Arcola. 

If Ascetoleberis has migrated from the west as hypothesized, this is additional evidence for the Arcola being time 

transgressive. 

CONCLUSIONS 

It is possible to document the stratigraphic separation 

between the Santonian-Campanian and Austinian-Tayloran 

Stage boundaries in the eastern Gulf Coastal Plain using a 

biostratigraphic framework composed of foraminifers, nannofossils, and ostracodes. In eastern Mississippi, the 

Santonian-Campanian boundary occurs within the Tombigbee Sand Member of the Eutaw Formation. The AustinianTayloran boundary occurs within the Mooreville Formation 

approximately 21 meters above the Santonian-Campanian 

boundary. In Alabama, the Santonian-Campanian boundary 

occurs within the Mooreville Formation, approximately 35 

meters above the Eutaw-Mooreville contact. The AustinianTayloran boundary occurs within the Mooreville Formation, approximately 36.5 meters above the SantonianCampanian boundary. The Arcola Limestone Member of 

the Mooreville Formation, previously used to designate the 

Austin ian-Tayloran boundary, lies well within the Tayloran 

Stage. 

TAXONOMIC NOTES 

In this section I list ostracode, foraminifer, and 

nannofossil taxa recorded in tables 1-3. Brief references to 

publications that document my concept of each taxon 

are included. Illustrations of selected taxa are provided in 

plates 1-6. 

Ostracoda 

Alatacythere cheethami (Hazel and Paulson) Hazel and 

Brouwers 

Plate 5, figure 4 

Alatacythere cheethami (Hazel and Paulson) Hazel and Brouwers, 

1982, p. 195, pl. 6, fig. 9. 

Brachycythere acuminata Hazel and Paulson 

Plate 5, figure 1 

Brachycythere (Brachycythere) acuminata Hazel and Paulson, 

1964, p. 1060, pl. 157, fig. 12; pl. 149, figs. 9, 11. 

Brachycythere durhami Hazel and Paulson 

Brachycythere (Brachycythere) durhami Hazel and Paulson, 1964, 

p. 1061, pl. 157, fig. 1; pl. 159, fig. 10. 

Cytheropteron furcalatum Alexander 

Plate 5, figure 5 

Cytheropteron furcalatum Alexander, 1933, p. 194, pl. 27, figs. 

7a, 7b. 

Ascetoleberis plummeri (lsraelsky) Brouwers and Hazel 

Plate 6, figure I 

Cythereis plummeri Israelsky, 1929, p. 18, pl. 4A, figs. 2, 3. 

Ascetoleberis plummeri (lsraelsky). Brouwers and Hazel, 1978, 

p. 35. 

Ascetoleberis rugosissima (Alexander) Brouwers and Hazel 

Plate 5, figure 2 

Cythereis rugosissima Alexander, 1929, p. 101, pl. 9, figs. 13, 

14. 

Ascetoleberis rugosissima (Alexander). Brouwers and Hazel, 

1978, p. 35. 

Veenia ozanana (lsraelsky) Butler and Jones 

Plate 5, figure 3 

Cythereis ozanana Israelsky, 1929, p. 13, pl 3a, figs. 1, 3. 

Veenia ozanana (lsraelsky). Butler and Jones, 1957, p. 44, pl. 3, 

fig. 4a-3. 

Veenia ponderosana (Israelsky) Hazel and Brouwers 

Plate 5, figure 6 

Cythereis ponderosana Israelsky, 1929, p. 13, pl. 3a, figs. 5-8. 

Veenia ponderosana (lsraelsky). Hazel and Brouwers, 1982, p. 

184, pl. 3, figs. 14-17. 

14 Santonian-Campanian and Austin ian-Tayloran Stage Boundaries in Miss. and Ala. Using Calcareous Microfossils 
Veenin quadrialira (Swain) Hazel and Brouwers 

Plate 6, figure 4 

Cythereis quadrialira Swain, 1952, p. 84, pl. 9, figs. 27-30. 

Veenia quadrialira (Swain). Hazel and Brouwers, p. 183, pl. 3, 

figs. 5, 9. 

Veenia spoori (lsraelsky) Hazel and Brouwers 

Plate 6, figure 2 

Cythereis spoori lsraelsky, 1929, p. 27, pl. 4a, figs. 4, 5. 

Veenia spoori (lsraelsky). Hazel and Brouwers, 1982, p. 176, pl. 

I, fig. 13. 

Physocythere annulospinata (Hazel and Paulson) Hazel and 

Brouwers 

Plate 6. figure 3 

Orthonotacythere annulospinata Hazel and Paulson, 1964, p. 

1049, pl. 157, figs. 2, 4; pl. 159, fig. 4. 

Physocythere annulospinata (Hazel and Paulson). Hazel and 

Brouwers, 1982, p. 192, pl. 5, fig. 16. 

Calcareous Nannofossils 

Aspidolithus parous (Stradner) Noel 

PIUie 7, figures 5, 9, 10 

Arkhange/skiella parca Stradner, 1963, p. 10, pl. 1, fig. 3. 

Aspidolithus pare us (Stradner) Noel, 1969. 

Bukryaster hayi (Bukry) Prins and Sissingh 

PIUie 7. figures 3, 4, 7. 8 

Discoaster hayi Bukry, 1969, p. 65, pl. 38, figs. 10-12. 

Bukryaster hayi (Bukry). Prins and Sissingh, in Sissingh, 1977, 

p. 60. 

Calculites obscurus (Deflandre) Prins and Sissingh 

Plate 7, figures II, 12 

Tetralithus obscurus Deflandre, 1959, p. 138, pl. 3, figs. 36-39. 

Ca/culites obscurus (Deflandre). Prins and Sissingh, in Sissingh, 

1977, p. 60. 

Calculites ovalis (Stradner) Prins and Sissingh 

Plate 7. figures 15, 16 

Tetralithus ova/is Stradner, 1963, p. 12, pl. 6, fig. 7. 

Calculi res oval is (Stradner). Prins and Sissingh, in Sissingh, 1977, 

p. 60. 

Ceratolithoides aculeus (Stradner) Prins and Sissingh 

Plate 7, figures I, 2, 6 

Zygrhablithus aculeus Stradner, 1961, p. 81, figs. 53-57. 

Ceratolithoides aculeus (Stradner). Prins and Sissingh, in Sissingh, 1977, p. 60, pl. I, fig. 8. 

Marthasterites furcatus (Deflandre) Deflandre 

Plate 7, figures 13, 14 

Diseoaster fureatus Deflandre, 1954, p. 168, pl. 13, fig. 14. 

Marthasteritesfurcatus (Deflandre). Deflandre, 1959, p. 139, pl. 

2, figs. 3-12; pl. 3, figs. 1-5. 

Foraminifera 

Az:chaeoglobigerina cretacea (d'Orbigny) Pessagno 

Plate I, figures 7-9 

Globigerina eretaeea d'Orbigny, 1840, p. 34, pl. 3, figs. 12-14. 

Arehaeoglobigerina eretaeea (d'Orbigny). Pessagno, 1967, p. 

317, 318, pl. 70, figs. 3-7. 

Dicarinella asymetrica (Sigal) 

Plate 4, figures 1, 2, 4 

Globotruneana asymetriea Sigal, 1952, p. 35, fig. 35. 

Diearinella asymetriea (Sigal). Robaszynski and Caron, 1979, p. 

61-66, pl. 51, figs. 1, 2; pl. 52, figs. 1, 2. 

Globotruncana area (Cushman) Cushman 

Plate I . figures 4-6 

Pulvinulina area Cushman, 1926, p. 23, pl. 3, figs. 1a-lc. 

Globotruneana area (Cushman). Cushman, 1927b, p. 169, pl. 28, 

figs. 15a-15c. 

Globotruncana linneiana (d'Orbigny) Cushman 

Plate 2, figures 2, 4, 7 

Rosa/ina linneiana d'Orbigny, 1839, p. 106, pl. 5, figs. 10-12. 

Globotruneana linneiana ( d 'Orbigny). Cushman, 1931, p. 90. 

Globotruncana ventricosa White 

Plate 3, figures 1-3, 5 

Globotruncana eanalieulata var. ventrieosa White, 1928, p. 284, 

pl. 38, figs. 5a-5c. 

Globotruncanita elevata (Brotzen) 

Plate I, figures 1-3 

Rotalia elevata Brotzen, 1934, p. 66, pl. 3, fig. C. 

Globotruneanita elevata (Brotzen). Robaszynski, Caron, Gonzalez, and Wonders, 1984, p. 228-230, pl. 27, figs. 1-3; pl. 

28, figs. 1-3. 

Marginotruncana marginata (Reuss) 

Plate 3, figures 4, 6 

Rosa/ina marginata Reuss, 1845, p. 36, pl. 8, figs. 54a, 54b, 74a, 

74b. 

Taxonomic Notes 15 
Rosita fornicata (Plummer) 

Plate 2, figures I, 3, 5 

Globotruncana fornicata Plummer, 1931, p. 198, pl. 13, figs. 

4-6. 

Rosita fornicata (Plummer). Robaszynski, Caron, Gonzalez, and 

Wonders, 1984, p. 250, pl. 38, figs. 1-5. 

Sigalia deflaensis (Sigal) Reiss 

PI"' 2, fig•« 61 . 

Guembelina (~entilabrella) deflaensis Sigal, 1952, p. 36, fig. 41. 

Sigalia deflaensis (Sigal). Reiss, 1957, p. 243. 

Ventilabrella llabrata Cushman . 

Plot< 3, fig"" 7 I 

Ventilabrella ~ggeri var. glabrata Cushman, 1938, p. 26, pl. 4, 

figs. 15-17b. 

Vaglnulina Jxana Cushman 

PI"' 4, fig""' 3,15 

Vaginulina texana Cushman, 1930, p. 30, pl. 4, figs. 2, 3. 

I 

i 

I 

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Deposits of Late Cretaceous age in west-central Alabama: 

Mississippi Geological Society, 14th field trip guide book, 

p. 11-14. 

Noel, D., 1969, Arkhangelskiella (coccolithes cretaces) et formes 

affines du Bassin de Paris: Rev. Micropaleontol., v. 11, 

no. 4, p. 191-204. 

Orbigny, A.D., 'd, 1839, Foraminiferes, in de la Sagra, R., 

Histoire physique, politique et naturelle de I'ile de Cuba: 

Paris, A. Bertrand, v. 2, p. 1-224. 

---1840, Memoire sur les foraminiferes de la Craie Blanche 

du Bassin de Paris: Soc. Geol. France, Mem., v. 4, no. 1, 

p. 1-51. 

Parks, W.S., 1958, Discussion on the foraminifera, in Mellen, 

F.F., Cretaceous shelf sediments of Mississippi: Mississippi 

State Geological Survey Bulletin, v. 85, p. 1-112. 

References Cited 17 
Perch-Nielsen, K., 1979, Calcareous nannofossils from the Cretaceous between the North Sea and the Mediterranean: lUGS 

ser. A, no. 6, p. 223-272. 

---1984, New Late Cretaceous and Paleogene calcareous 

nannofossils: Eclog. geol. Helv., v. 77, no. 3, p. 1-18. 

---1985, Mesozoic calcareous nannofossils, in Bolli, H.M., 

Saunders, J.B., and Perch-Nielsen, K., Plankton stratigraphy: Cambridge University Press, p. 329-426. 

Pessagno, E.A., Jr., 1967, Upper Cretaceous planktonic foraminifera from the western Gulf Coastal Plain: Paleontographica 

Americana, v. 5, no. 37, p. 245-445. 

Plummer, H.J., 1931, Some Cretaceous foraminifera in Texas: 

University of Texas Bulletin 3101, p. 109-203. 

Postuma, J.A., 1971, Manual of planktonic foraminifera: Amsterdam, Elsevier, 412 p. 

Premoli Silva, I., and Boersma, A., 1977, Cretaceous planktonic 

foraminifers, in Initial reports of the Deep Sea Drilling 

Project, v. 39: Washington, D.C., U.S. Government Printing 

Office, p. 615-641. 

Reiss, Z., 1957, Notes on foraminifera from Israel: 3, Sigalia, A 

new genus of foraminifera: Israel Geological Survey Bulletin 

9, p. 242-245. 

Reuss, A.E., 1845, Die Versteinerungen der bohmischen Kreideformation: E. Schweizerbartsche Stuttgart, Abt. 1, pt. 2, 

p. 1-58. 

Robaszynski, F., and Caron, M., 1979, Atlas de Foraminiferes 

planctoniques du Cretace Moyen: Cah. Micropaleontol., 

pt. 1, p. 1-145; pt. 2, p. 1-181. 

Robaszynski, F., Caron, M., Gonzalez, J.M., and Wonders, A., 

1984, Atlas of Late Cretaceous planktonic foraminifera: Rev. 

Micropaleontol., v. 26, p. 145-305. 

Ross, J.E., and Maddocks, R.F., 1983, Recurrent species associations and species diversity of Cytheracean ostracodes in 

the Upper Austin and Lower Taylor Groups (Campanian, 

Upper Cretaceous) of Travis County, Texas: Gulf Coast 

Association of Geological Societies Transactions, v. 33, 

p. 397-406. 

Roth, P. H., 1973, Calcareous nannofossils, in Initial reports of the 

Deep Sea Drilling Project, leg 17: Washington, D.C., U.S. 

Government Printing Office, p. 695-795. 

Roth, P.H., and Thierstein, H.R., 1972, Calcareous nannoplankton, in Initial reports of the Deep Sea Drilling Project, v. 14: 

Washington, D.C., U.S. Government Printing Office, 

p. 421-485. 

Russell, E.E., and Keady, D.M., 1982, Notes on Upper Cretaceous lithostratigraphy of the eastern Mississippi embayment, 

in Russell, E.E., Keady, D.M., Mancini, E.A., and Smith, 

C.C., Upper Cretaceous in the lower Mississippi embayment 

of Tennessee and Mississippi: Lithostratigraphy and biostratigraphy: New Orleans, La., Earth Enterprises, Inc., 

p. 1-14. 

Russell, E.E., Keady, D.M., Mancini, E.A., and Smith, C.C., 

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de Ia Tunisie Septentrionale et Orientale: Geologique de 

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Aquitaine septrionale, ses stratotypes. Coniacien, Santonien, 

Campanien. France: Paris, Editions du Centre National de Ia 

Recherche Scientifique, 195 p. 

Shaver, R.H., 1958, Discussion on the ostracoda, in Mellen, F.F., 

Cretaceous shelf sediments of Mississippi: Mississippi State 

Geological Survey Bulletin, v. 85, p. 1-112. 

Shumard, B.F., 1860, Observations upon the Cretaceous strata of 

Texas: Academy of Sciences of St. Louis Transactions, v. 1, 

p. 582-590. 

Sigal, J., 1_952, Apercu stratigraphique sur Ia micropaleontologie 

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Monographies Regionales, ser. 1, no. 26, p. 1-47. 

---1977, Essai de zonation du Cretace mediterraneen a I' aide 

des foraminiferes planktoniques: Geologie Mediterraneen, 

v. 4, no. 2, p. 99-108. 

Sissingh, W., 1977, Biostratigraphy of Cretaceous calcareous 

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Smith, C.C., 1975, Upper Cretaceous calcareous nannoplankton 

and stage boundaries: Gulf Coast Association of Geological 

Societies Transactions, v. 25, p. 263-278. 

Sohl, N.F., 1964, Gastropods from the Coffee Sand (Upper 

Cretaceous) of Mississippi: U.S. Geological Survey Professional Paper 331-C, p. C345-C395. 

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of the Chattahoochee River valley, western Georgia and 

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Ga. 

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R.W., 1942, Geological Society of America Bulletin, v. 53, 

p. 435-448. 

Stephenson, L.W., and Monroe, W.H., 1940, The Upper Cretaceous deposits: Mississippi State Geological Survey Bulletin 

40, p. 1-296. 

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---1963, New contributions to Mesozoic stratigraphy by 

means of nannofossils: World Petroleum Congress, 6th, 

Frankfurt, section 1, paper 4, p. 1-16. 

Stradner, H., and Papp, A., 1961, Tertiare Discoasteriden aus 

Osterreich und deren stratigraphische Bedeutung mit Hinweisen auf Mexico, Rumanien und Italien: Jahrb. geol. 

Bundensanst. (Wein), special v. 7, p. 1-159. 

Stradner, H., and Steinmetz, J., 1984, Cretaceous calcareous 

nannofossils from the Angola Basin, Deep Sea Drilling 

Project site 530, in Initial reports of the Deep Sea Drilling 

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Office, p. 565-649. 

Swain, P.M., 1952, Ostracoda from wells in North Carolina: Part 

2, Mesozoic ostracoda: U.S. Geological Survey Professional 

Paper 234-B, p. B59-B93. 

Thierstein, H.R., 1976, Mesozoic calcareous nannoplankton biostratigraphy of some marine sediments: Marine Micropaleontology, v. 1, p. 325-362. 

Verbeek, J. W., 1977, Calcareous nannoplankton biostratigraphy 

of Middle and Upper Cretaceous deposits in Tunisia, south18 Santonian-Campanian and Austinian-Tayloran Stage Boundaries in Miss. and Ala. Using Calcareous Microfossils 
ern Spain and France: Utrecht Micropaleontological Bulletin 

6, p. 1-157. " 

White, M.P., 1928, Some index foraminifera from the Tampico 

embayment area of Mexico: Journal of Paleontology, v. 2, 

no. 4, p. 280-317. 

Wonders, A.A.H., 1980, Planktonic foraminifera of the Mediterranean area: Utrecht Micropaleontological Bulletin 24, 

p. 1-158. 

Young, Keith, 1963, Upper Cretaceous ammonites from the Gulf 

Coast of the United States: Texas University Publication 

6304, p. 1-373. 

---1982, Cretaceous rocks of central Texas-Biostratigraphy 

and lithostratigraphy, in Maddocks, R.F., ed., Texas ostracoda: Houston, Tex., University of Houston Department of 

Geosciences, p. 111-126. 

References Cited 19 
APPENDIX: LOCALITIES 

Selma core: Officially designated the Alabama Power 

Company South Selma Test Site 1, Corehole 3; taken 0.5 

mile west of the Mount Leveton Church, on the east side of 

the Alabama River, 14 miles' south-southwest of Selma, 

Dallas County, Ala. Twenty-five samples were selected 

from this core, which contains the Tombigbee Sand Member of the Eutaw Formation, the Mooreville Formation, 

including the Arcola Limestone Member, and the Demopolis Formation. 

China Bluff: An exposure in a small gully on the west 

side of the Tombigbee River, approximately 2 miles south 

of Warsaw, Sumter County, Ala., near the site of a U.S. 

Army Corps of Engineers China Bluff observation area and 

nature trail. Eight samples were selected from this exposure 

of the upper part of the Mooreville Formation, including the 

Arcola Limestone Member. 

DW-24: U.S. Army Corps of Engineers dewatering 

well no. 24, taken at the site of the Columbus lock and dam, 

at the intersection of Tibbee Creek and the Tombigbee 

River, Lowndes County, Miss. Five samples were selected 

from this 40-foot, 4-inch-diameter core, which begins 20 

feet below the surface in the Tombigbee Sand Member of 

the Eutaw Formation and penetrates the lower, unnamed 

member of the Eutaw Formation. 

Plymouth Bluff: A long continuous exposure along 

the west bank of the Tombigbee River, approximately 1.2 

miles downstream from the intersection of Tibbee Creek 

and the Tombigbee River, 4 miles west-northwest of 

Columbus, Lowndes County, Miss. Seven samples were 

selected from this locality, which exposes the uppermost 

Tombigbee Sand Member of the Eutaw Formation and the 

lowest Mooreville Formation. 

Tibbee Creek: An exposure on the south bank of 

Tibbee Creek, immediately west of the point where the 

Gulf, Mobile, and Ohio Railroad bridge crosses Tibbee 

Creek, Clay County, Miss. Five samples were selected 

from this locality, which exposes the upper Mooreville 

Formation, including the Arcola Limestone Member, and 

the lowest Demopolis Formation. 

20 Santonian-Campanian and Austinian-Tayloran Stage Boundaries in Miss. and Ala. Using Calcareous Microfossils 
PLATES 1-7 

[Contact photographs of the plates in this report are available, at cost, 

from the U.S. Geological Survey Photographic Library, Federal Center, 

Denver, CO 80225] 
PLATE 1 

Figures 1-3. Globotruncanita elevata (Brotzen) 

1. Spiral view, x 12Q, ALA 7. 

2. Apertural view, X 120, ALA7. 

3. Umbilical view, X 120, ALA7. 

4-6. Globotruncana area (Cushman) Cushman 

4. Spiral view, X 120, ALAlO. 

5. Apertural view, x 120, ALAlO. 

6. Umbilical view, X 120, ALA10. 

7-9. Archaeoglobigerina cretacea (d'Orbigny) Pessagno 

7. Spiral view, x 180, ALA20. 

8. Apertural view, x 180, ALA20. 

9. Umbilical view, x 180, ALA20. 
U.S. GEOLOGICAL URVEY BULLET! 1884 PLATE 1 

ARCHAEOCLOBICERINA, CLOBOTRUNCANA, AND CLOBOTRUNCANITA 
PLATE 2 

Figures 1, 3, 5. Rosita fornicata (Plummer) 

1. Umbilical view, x 180, ALAlO. 

3. Spiral view, X 180, ALA10. 

5. Apertural view, x 180, ALA10. 

2, 4, 7. Globotruncana linneiana (d'Orbigny) Cushman 

2. Umbilical view, x 150, ALA21. 

4. Spiral view, X 150, ALA21. 

7. Apertural view, x 150, ALA21. 

6. Sigalia deflaensis (Sigal) Reiss, x 180, ALA3. 
U.S. GEOLOGI CAL SURVEY BULLETIN 1884 PLATE 2 

GLOBOTRUNCANA, ROSITA, AND SIGAL/A 
PLATE 3 

Figures 1-3, 5. Globotruncana ventricosa White 

1. Umbilical view, x 160, ALA2. 

2. Abapertural view, x 180, ALA2. 

3. Apertural view, x 180, ALA2. 

5. Spiral view, x 160, ALA2. 

4, 6. Marginotruncana marginata (Reuss) 

4. Umbilical view, x 78, ALA4. 

6. Apertural view, x 120, ALA4. 

7. Ventilabre/la glabrata Cushman, x 160, ALAlO. 
U.S. GEOLOGICAL SU RVEY BU LLETI 1884 PLATE 3 

GLOBOTRUNCANA, MARGINOTRUNCANA, AND VENTILABRELLA 
PLATE 4 

Figures 1, 2, 4. Dicarinella asymetrica (Sigal) 

1. Spiral view, x 120, ALAS. 

2. Umbilical view, x 120, ALAS. 

4. Apertural view, x 120, ALAS. 

3, 5. Vaginulina texana Cushman 

3. Side view, X 70, ALAIO. 

5. Side view, x 44, ALA4. 
U.S. GEOLOGICAL SU RVEY BULLETIN 1884 PLATE 4 

3 

0/CAR/NELLA AND VACINULINA 
PLATE 5 

Figure 1. Brachycythere acuminata (Hazel and Paulson), x 110, ALA48. 

2. Ascetoleberis rugosissima (Alexander) Brouwers and Hazel, x 94, MIS65. 

3. Veenia ozanana (lsraelsky) Butler and Jones, x 120, ALA4. 

4. Alatacythere cheethami (Hazel and Paulson) Hazel and Brouwers, x 110, 

ALA9. 

5. Cytheropteron furcalatum Alexander, X 120, ALA10. 

6. Veenia ponderosana (lsraelsky) Hazel and Brouwers, x 86, ALA4. 
U.S. GEOLOGICAL SU RVEY BULLET! 1884 PLATE 5 

6 

ALA TA C YTHERE, A SCETOLEBER/5, BRACHYCYTHERE, CYTHEROPTERON, AND VEENIA 

2 

4 
PLATE 6 

Figure 1. Ascetoleberis plummeri (lsraelsky) Brouwers and Hazel, X 86, MIS65. 

2. Veenia spoori (lsraelsky) Hazel and Brouwers, x 130, ALA20. 

3. Physocythere annulospinata (Hazel and Paulson) Hazel and Brouwers, x 180, 

ALA12. 

4. Veenia quadrialira (Swain) Hazel and Brouwers, x 150, ALA3. 
U.S. GEOLOGICAL SURVEY BULLETIN 1884 PLATE 6 

ASCETOLEBERIS, PHYSOCYTHERE, AND VEENIA 
PLATE 7 

[All photographs x I ,600] 

Figures 1, 2, 6. Ceratolithoides aculeus (Stradner) Prins and Sissingh 

1. Phase contrast, ALA26. 

2. Cross polarized, ALA26. 

6. Cross polarized, ALA26. 

3, 4, 7, S. Bukryaster hayi (Bukry) Prins and Sissingh 

3. Phase contrast, ALA11. 

4. Cross polarized, ALA 11. 

7. Phase contrast, ALA 11. 

S. Cross polarized, ALAll. 

5, 9, 10. Aspidolithus parcus (Stradner) Noel 

5. Cross polarized, ALAS. 

9. Cross polarized, ALAS. 

10. Phase contrast, ALAS. 

11, 12. Calculites obscurus (Deflandre) Prins and Sissingh 

11. Cross polarized, ALA15. 

12. Cross polarized, ALA15. 

13, 14. Marthasterites furcatus (Deflandre) Deflandre 

13. Cross polarized, ALA13. 

14. Cross polarized, ALA13. 

15, 16. Calculites ovalis (Stradner) Prins and Sissingh 

15. Phase contrast, ALAlO. 

16. Cross polarized, ALAlO. 
r 

U.S. GEOLOGICAL SURVEY BU LLETIN 1884 PLATE 7 

1 2 3 4 

5 6 7 8 

9 10 11 12 

13 14 15 16 

ASP/DOL/THUS, BUKRYASTER, CALCULITES, CERATOLITHOIOES, AND MARTHASTERITES 

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Dowsett-SANTONIAN:-CAMPANIAN AND AUSTINIAN-TA~ LORAN STAGE BOUNDARIES IN MISS. AND ALA. - U.S