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Revue de Micropaéeontologie Vol. 2, nº 4, pp. 219-230. March 1960.


by R.M. Stainforth*

Résumé. — Des corrélations au moyen de Foraminifères planctoniques ont été réalisées avec succès dans les sédiments oligo-miocènes des régions antillaises et sud-américaines. Dans les régions méditerranéennes, les Foraminifères planctoniques de l’Oligo-miocène n’avaient guère retenu l’attention jusqu’a ces dernières années. Mais, il est maintenant possible de faire des corrélations entre ces deux régions; tel est le but de cet article qui conduit à reconnaître, en Amérique, l’Aquitanien supérieur, le Burdigalien, l’Helvétien et le Tortonien. En ce qui concerne l’Oligocène et l’Aquitanien inférieur d’Amérique, les résultats sont plus incertains, a partir de données souvent contradictoires.


During the past forty years the Tertiary micropaleontology of the Antillean-South American region has been studied intensively, largely as an adjunct to petroleum geology. In particular the life-ranges of foraminifera were applied successfully to solving problems of local correlation. The next logical step was to apply them to regional correlation. For many years only the benthonic (bottom-living) species were considered for this purpose, but appreciable success was achieved by empirical comparison of their distribution in different areas and, to a lesser extent, by recognition of evolutionary sequences. The weakness of this technique is that the similarity, even the identity, of benthonic microfaunas may arise from ecologic, not chronologic, causes. A clearcut case of ambiguity arising from this cause is Dorr’s correlation (1933) of four deceptively similar deep-water microfaunas in Central and South America, now recognized as differing appreciably in age. A corollary is that the age-equivalence of two benthonic microfaunas may remain unrecognized because environmental factors make them utterly dissimilar.

Locally, and especially in Trinidad, the problem of distinguishing between the chronologic and ecologic aspects of microfaunas became so acute that special efforts were made to solve it. The solution, once found, was an easy one, simply to concentrate on the surface-living planktonic foraminifera whose distribution in the sediments was barely influenced by environmental factors of the sea-floor. In the Oligo-Miocene of the region a well-defined sequence of planktonic species was found, permitting division of the interval into several zones which could be identified in sediments representing every environment from shallow marine to abyssal. In the interval 1948-1951 a series of papers appeared which established the regional validity of this planktonic zonation, and since that time it has achieved wide acceptance.

As regards the age of the zones, this planktonic zonation was first established in Trinidad, hence it was natural to adopt the time-scale in use in that island. On that basis the Oligocene/Miocene boundary was first placed at the contact between the Globorotalia fohsi zone and the overlying Globorotalia menardii zone. Later dissatisfaction was expressed with this scheme, initially stemming from its assumed inclusion of the Aquitanian stage in the Oligocene, whereas the modern tendency is to treat the Aquitanian as Miocene. Furthermore, reasons have been given for considering the Globorotalia fohsi zone Burdigalian rather than Aquitanian. The result has been to reduce the Oligocene interval recognized in the Antillean-South American region.

The evidence used in this second phase of deciding on placement of the Oligocene/Miocene boundary within the American planktonic zones was partly indirect, based on other groups of fossils. It is not discussed or documented at length in this paper (though the principal references are listed) because transatlantic correlation of the zones has now, entered on its third phase of direct comparison. When the regional planktonic zonation was established in the New World there were no significant records of the distribution of the index-species in the Old World. Within the past few years, however, this situation has changed. The proven success of the technique in America has stimulated micropaleontologists in the Mediterranean region to list the planktonic foraminifera in some detail in their microfaunal inventories of various stratigraphic units. The cumulative result is an unsorted mass of records, potentially applicable to regional zonation and correlation.

The main purpose of the present paper is to compile these published data on the planktonic foraminifera in the Oligocene and Miocene of the Mediterranean region, then to compare their distribution with the established planktonic zonation of the Antillean-South American region. The outcome should be direct age-determination of the American zones in terms of the standard European stages. This objective has been achieved to a considerable extent and as far as it goes this transatlantic correlation is the most direct, hence presumably the most reliable, yet attained. Nevertheless there is scope for greatly improving its precision by further detailed studies. In particular the position of the Oligocene/Miocene (i.e. Chattian/ Aquitanian) boundary remains indefinite within the American sequence.

In this paper the American Oligo-Miocene is divided into the five major zones which were recognized, either formally or informally, in the first published references to regional planktonic zonation (e.g. Stainforth, 1948-b, p. 1302-1306). These zones are defined by the ranges of well known species which have been regularly reported in Mediterranean microfaunas, hence they form a practical basis for preliminary transatlantic correlation. It is recognized that a finer zonation is coming into use in America, first defined in Trinidad (Bolli, 1957) but already identified elsewhere (Blow, 1959; Woodring, 1958). However, the Mediterranean records are not yet precise enough for recognition of the new subdivisions. It must be a goal of future studies to apply the new zonation to both intraregional and transatlantic correlation. The equivalence between the original and the new schemes is tabulated below.


Zonal units of this paper


Subdivisions of Bolli (1957-a)

Zone of


Zone of

Globorotalia menardii

Globorotalia menardii

Globorotalia mayeri

Globorotalia fohsi

Globorotalia fohsi robusta

Globorotalia fohsi lobata

Globorotalia fohsi fohsi

Globorotalia fohsi barisanensis

Globigerinatella insueta

Globigerinatella insueta

Catapsydrax stainforthi

Globigerina dissimilis

Catapsydrax dissimilis

Globorotalia kugleri

Globigerina ciperoensis

Globigerina ciperensis

Globorotalia opima opima

Globigerina ampliapertura

The author expresses his thanks to the Creole Petroleum Corporation for permission to prepare and publish this paper. The original version was prepared for the Third Venezuelan Geological Congress and is due to be printed in Spanish. The present paper is a re-written version which includes and comments upon new data. Its preparation was materially assisted by discussions with Drs. H. M. Bolli, H. H. Renz and J. B. Saunders and by correspondence with Dr. W. H. Blow.


Since 1951 many papers on the Mediterranean region have included lists of Tertiary planktonic foraminifera. The large mass of data involved can most simply be presented on a distribution chart (figure). This shows the recorded ranges of Oligo-Miocene planktonic foraminifera in the Mediterranean region, with separation into four geographic sectors. The pattern of distribution of the same species in America is superimposed, and a close correspondence is evident. Nevertheless some discrepancies of species-ranges are to be expected in the compilation of heterogeneous data. The compiler must be objective in accepting authors’ identification of ages and species, even though he may have subjective reasons for doubt.

In the following summary the source-references for the Mediterranean species-ranges are noted, and comments are added on discrepancies and uncertainties. The species are discussed in their order of entry on the distribution chart. References are only dated where authors are listed more than once in the bibliography. In the Italian literature the «Langhiano» is treated as synonymous with the Burdigalian, a procedure which leads to no obvious discrepancies despite Drooger’s claim (1954-a) that it is incorrect.

Globigerina ampliapertura Bolli 1957

• (U.S. Nat. Mus., Bull. 215, p. 108, pl. 22, fig. 4-7).

This is a newly erected species and its records are largely tentative, based on assumed identity with forms listed under older names. The only definite published record appears to be in the late Oligocene of Algeria (Drooger et Magné). Tentative records include the Oligocene of Spain (Durand-Delga et Magné, as «G. gr. globularis»); the Stampian-Chattian of France (Drooger, 1956b, as «G. globularis») ; and the Lattorfian of Italy (Di Napoli), 1952, as «G. inflata»). The present writer has observed this species in the basal Oligocene of Egypt (Stainforth, 1949, as «Globorotalia centralis var.») and France (unpublished) and was notified of its presence in the basal Oligocene of Israel by Z. Reiss (private communication).

Globigerina ciperoensis Bolli 1954

• (Cushman Lab. Foram. Res., Contr., vol. 5, p. 1, fig. 3).

This important species has not yet been widely recorded but may have been included in records of the similar G. concinna Reuss. The limited records include the lower Aquitanian of Sicily (Blow, 1957) ; the Chattian of France (Drooger, 1956b; G. Malmoustier, private communication) and the basal Oligocene of Egypt (Stainforth, 1949, as «G. concinna »).

Globigerina dissimilis Cushman et Bermúdez 1937

• (Cushman Lab. Foram. Res., Contr., vol. 13, p. 25, pl. 3, fig. 4-6).

This species is so consistently recorded from the Oligocene and Aquitanian that a list of references is unnecessary. Comment is only made on the post-Aquitanian records, which are considered dubious. One is by Colom (1956, 1958) in Majorca, where the author notes certain Aquitanian affinities although the beds under discussion are treated as Burdigalian. It seems possible in this case that precise documentation would restrict G. dissimilis to the Aquitanian. Colom’s 1958 paper was partly issued as a correction to Drooger’s claim (1956-b) that this Majorcan fauna was as young as Helvetian. Likewise Blow (1957) and Eames and Clarke have corrected Drooger’s chronology, which placed G. dissimilis-bearing beds of Morocco in the Burdigalian-Helvetian interval.

Globigerinoides triloba (Reuss) 1850

• (Denkschr. Akad. Wiss. Wien. Math.-Nat. Classe, vol. 1, p. 374, pl. 47, fig. 11).

Globoquadrina altispira (Cushman and Jarvis) 1936

• (Cushman Lab. Foram. Res., Contr., vol. 12, p. 5, pl. 1, fig. 14, 14).

Globorotalia mayeri Cushman and Ellisor 1939

• (ibid., vol. 15, p. 11, pl. 2, fig. 4).

The members of this trio of species have almost identical stratigraphic significance. They are all consistently recorded from the Aquitanian into the Vindobonian, though neither G. altispira nor G. mayeri appears to have been recorded in the Tortonian by authors who subdivide the Vindobonian. Of special interest, since they seem to conflict with the upper range of G. ciperoensis, are sundry records of these species in the Stampian-Chattian interval. The following references include such mention: Spain-Colom, 1951 (text but not chart); Drooger, 1956-a (questionable); Italy-A.G.I.P., 1957; Ascoli, 1956; Di Napoli, 1952, 1953: North-Africa-Drooger and Magné; Rey: France-Stainforth, unpublished.

Globigerinatella insueta Cushman and Stainforth 1945

• (Cushman Lab. Foram. Res., Spec. Pub. 14, p. 69, pl. 13’ fig. 7-9).

Globigerinoides bisphericus Todd 1956

• (Amer. Jour. Sci., vol. 252, n° 11, p. 681, pl. 1, fig. 1, 4).

Globigerinoides glomerosus Blow 1956

• (Micropaleontology, vol. 2, p. 65, text, fig. 1, n° 15-19; text-fig. 2, n° 1-2).

Globigerinoides transitorius Blow 1956

idem (text-fig. 2, n° 12-15).

Members of this suite first appeared in the late Aquitanian and the specialised forms did not survive into the Burdigalian according to the records of Blow (Sicily and Malta), Durand-Delga and Magné (Spain) and Hagn (Greece). Colom (1958) indicates G. glomerosus and G. transitorius ranging up into the Vindobonian but, in view of Blow’s demonstration that these are stages in a rapidly evolving sequence, such a long upward extension appears unlikely.

The G. bisphericus form was apparently more stable and persistent and is also recorded in the post-Aquitanian by Colom, 1958 (Majorca), Drooger, 1956-b (Morocco, Majorca, Italy, but chronology open to question) and Stainforth, 1949 (Egypt, as «G. conglobatus»). Ferreira records G. bisphericus from Portugal but gives no local evidence indicative of its age. These higher records of G. bisphericus are noted here but are omitted from the distribution start in order to emphasize the stratigraphic significance of the whole suite.

Orbulina sp.

The genus Orbulina is mentioned in almost every list of Burdigalian and Vindobonian plankton. The only significant record of it in pre-Burdigalian beds is in Spain, where Colom (1952), Colom and Gamundi, and Durand-Delga and Magné all record the genus in (lower) Aquitanian beds. This is such an anomalous record that an error of age determination must be suspected.

Globorotalia praemenardii Cushman and Stainforth 1945

• (Cushman Lab. Foram. Res., Spec. Pub. 14, p. 70, pl. 13, fig. 14).

This species is recorded in Spain in the three references just noted, in which a Burdigalian age appears much more probable than the Aquitanian age claimed. It is also noted in the Burdigalian of Algeria by Colom and Muraour and Dame and Magné. Nominal records of G. menardii by A.G.I.P. and Ferasin in the Burdigalian of Italy are suspected to refer to G. praemenardii.

Globorotalia fohsi Cushman and Ellisor 1939

• (Cushman Lab. Foram. Res., Contr., vol. 15, p. 12, pl. fig. 6).

This species has not been widely recorded, but the few mentions of it are all from Burdigalian beds, viz. Blow (1957) - Malta ; Colom (1956, 1958) Majorca; Colom and Muraour -Algeria; and Hagn Greece.

Globorotalia menardii (d’Orbigny) 1826

• (Ann. Sci. Nat., vol. 7, p. 273).d

This species appears in most lists of Vindobonian assemblages. The only two pre-Vindobonian references encountered are not specifically figured and mis-identification of G. praemenardii is suspected (see above).

Sphaeroidinella sp.

Reference is to the vitreous forms variously identified as S. rutschi, S. seminula, S. dehiscens, etc. and excludes the non-vitreous forms of S. grimsdalei. Only three records have been noted on the Mediterranean literature but all are in the Vindobonian, namely in Italy (A.G.I.P.), Sicily (Blow, 1957) and Majorca (Colom, 1958).


On the accompanying distribution chart (fig. 1) the relative ranges of planktonic species in America are plotted, following Bolli (1957-a, p. 99). Strictly these data refer only to Trinidad, but in the author’s experience they are valid regionally. To a large extent the recorded order of appearance and extinction of species is the same on both sides of the Atlantic, hence the matching of American zones with European stages becomes almost self-evident. However, before discussing details it is desirable to emphasize certain factors which affect the reliability of transatlantic correlations, viz.

— 1. Age-determination. It has been widely admitted that the existing chronology of the European Tertiary is imperfect. The accepted sequence of stages probably includes both overlaps and lacunas, if compared to an ideal time-scale. The dominance of shallow-marine sediments in the classic type areas of the stages hinders precise dating of the deeper-marine sediments best suited for planktonic zonation. In this connection there is a great need for publication on subsurface sections (water and oil wells) which aid in correlating between the peripheral and axial provinces of sedimentary basins. Specialists in different phyla of fossils, such as the Mollusca, Echinoidea and Miogypsinidae, still tend to differ in their age determinations. Concerted international effort is desirable to improve the situation. Meanwhile some flexibility must be allowed in accepting authors’ references of Oligo-Miocene faunas to particular levels in the Mediterranean stages.

— 2. Species-determination. Morphologic adaptation to a specialized existence leads to homeomorphic tendencies among the planktonic foraminifera. Consequently speciation is based on rather fine differences. Almost all the index-species listed on the distribution chart could conceivably be confused with other species which occur at different stratigraphic levels. This is especially true in the shallower-marine sediments, in which the plankton is often small and immature. Consequently some discretion must be permitted in accepting seemingly anomalous records. Careful figuring and description of the species recorded is, unfortunately, exceptional in the Mediterranean literature compiled in this paper.

— 3. Ecologic factors. In principle the planktonic foraminifera are hardly affected by ecologic factors and for this reason are exceptionally useful zonal indices. Actually it has been noted in America that within a given zone the diversity of plankton diminishes progressively from deeper to shallower marine deposits. For instance, the Cipero formation of Trinidad and the Carapita formation of E. Venezuela intergrade laterally and respectively represent the very deep axial and the medium-depth to shallow peripheral provinces of a single basin. At certain levels in the Cipero marls Globigerinatella insueta and Globorotalia fohsi occur in abundance, but in the Carapita formation both species are scarcer. In the littoral to sublittoral deposits of the basin these species are almost absent and plankton in general is scarce and diminutive, although long-ranging species such as Globigerinoides triloba and Globorotalia mayeri are often present. In the Mediterranean region a comparable situation seems to exist, since records of both G. insueta and G. fohsi are very scanty, whereas G. triloba and G. mayeri are widely recorded.

These observations indicate some local ecologic control of distribution of plankton. Also important is regional control related to climatic belts. Studies of Recent plankton indicate marked preference of certain species for certain latitudes, ranging from tropical to sub-polar. In the Neogene the Antillean and Mediterranean planktonic assemblages are quite similar and represent the equatorial to sub-tropical belt, but there is evidence (e.g. Drooger, 1956-b) that the plankton of the boreal parts of Europe is quite different. It seems equally probable that a third distinctive suite of plankton may typify the austral parts of Africa and South America.

These aspects of the technique must be considered, at least tacitly, in applying the distribution of plankton to long-range and transoceanic correlations. Their net effect is to lower the precision of the results. This branch of biostratigraphy is still in a preliminary stage, and correlations now offered are subject to change as more data are collected and properly assessed. With these stipulations in mind, an attempt can now be made to apply the accompanying distribution chart to a direct correlation of the American zones with the Mediterranean stages.

A key point in transatlantic correlation, first noted by Blow (1957), is that the short-lived suite of Globigerinatella insueta, Globigerinoides glomerosus and G. transitorius, which defines the American G. insueta zone, is confined to the upper Aquitanian of the Mediterranean region.

Above this the first appearance of Orbulina, coupled with the short life-ranges of Globorotalia fohsi and G. praemenardii, defines equally the American G. fohsi zone and the Burdigalian stage of Europe and North Africa.

Still higher, the appearance of Globorotalia menardii and vitreous Sphaeroidinella above the level of extinction of G. fohsi indicates direct correlation between the American G. menardii zone and the Helvetian-Tortonian (Vindobonian) interval in the Old World. It is interesting to note that Bolli’s use of the level of extinction of G. mayeri to subdivide the G. menardii zone is also valid across the ocean, where it serves to separate the Helvetian from the Tortonian.

Hence the three upper zones in the American scheme appear to be precisely dated, in terms of the European stages, by direct comparison of planktonic microfaunas. It follows that the two lower zones in America represent the Oligocene and the lower Aquitanian, but the level of separation of these two zones is still open to some question. They are defined in America by the non-overlapping ranges of G. ciperoensis and G. ampliapertura below and of G. trilova-group, G. altispira and G. mayeri above. In contrast the Mediterranean literature indicates a pronounced overlap in the ranges of these five species, extending from the Stampian into the Aquitanian. It is this anomalous overlap of recorded ranges which accounts for the ambiguity.

The worldwide distribution of pre-Oligocene planktonic foraminifera is better documented than that of the Oligo-Miocene species. In this voluminous literature the author knows of no important case of species-ranges which overlap in one region but not in another. He therefore tends, by analogy, to suspect that the anomaly under discussion arises from erroneous data. Whether the error resides in faulty determination of age or in faulty identification of species cannot yet be detected. It seems unlikely that the anomaly has an ecologic or climatic cause.

Depending on which criterion is accepted for recognition of the G. ciperoensis zone in the Mediterranean region, two very different correlations result. If the levels of extinction of the name-species are matched across the Atlantic, then the G. ciperoensis zone represents the whole Oligocene and the basal Aquitanian. But if the levels of first appearance of the G. triloba-G. altispira-G. mayeri suite are matched, then the G. ciperoensis zone is confined to the Lower Oligocene (Lattorfian).

The present writer’s tendency in the past was to accept the latter correlation for several reasons. One was the longstanding tendency of paleontologists in general to place the base of the Middle Oligocene in America at a level which corresponds with the base of the G. dissimilis zone. Another reason was the generalization that the first appearance of distinctive new species, especially when coincident with widespread marine transgression, has fundamental significance in biostratigraphy. (cf. Glaessner, 1953, p. 649 «The first regional appearance of a new fauna… is the basic time-marking event in stratigraphy.»). The writer had personally noted appearance of the triloba-altispira-mayeri suite in the subsurface of Aquitaine in beds identified by local geologists as Stampian resting unconformably on « Sannoisian (Lattorfian), these lower beds being referred to the basal G. ciperoensis zone by the presence of G. ampliapertura. He therefore accepted the scattered records of the triloba-altispira-mayeri suite in Stampian-Chattian beds unquestioningly, especially as this led to the attractive concept of correlating the Stampian-Rupelian transgression in Europe with the so-called mid-Oligocene (G. dissimilis zone) transgression in America.

However, it must be admitted that new evidence has weakened the validity of these arguments. The records of G. ciperoensis and G. ampliapertura at Chattian-Aquitanian levels are contradictory to the postulated correlation. Certain authors state or imply that the triloba-altispira-mayeri suite is post-Oligocene in the Mediterranean region (e. g. Dame and Magné, 1956). The comparison of American and Mediterranean Miogypsinidae by Drooger, Eames and others tends to suggest an Aquitanian age for the G. dissimilis zone.

The conflicting lines of evidence will be resolved as gaps in present knowledge are filled, and the question is here left open. The first step in solving a problem is to state it, as has been done above. It now remains to scrutinize and amplify the Mediterranean records of the five index-species under discussion, with careful regard to correctness of identification and age-determination.


As noted in the introduction, the American zonation was developed before much information was available on the Mediterranean planktonic microfaunas. First attempts to date the zones therefore relied mainly on existing ideas derived from study of other fossil groups, mostly benthonic. Nevertheless some pioneer attempts were made to utilise planktonic organisms in direct transatlantic correlation, and the following paragraphs comment on these papers.

R. Rutsch (1934), at the suggestion of H.G. Kugler, made direct comparison of the pteropods (planktonic mollusks) of Trinidad with European forms. From the Ste-Croix limestone, which straddles the G. insueta and G. fohsi zones, he recorded Vaginella cf. lapugyensis, Cavolina audeninoi var., Clio pulcherrima and C. cf. lavaysea. At a corresponding level in Venezuela he again noted Clio pulcherrima (fide Senn, 1935). A close similarity was noted to the pteropod assemblage of the Italian Miocene. This early direct age determination conforms closely with present-day opinion, but for a long time it was overridden by evidence seeming to point to an Oligocene age.

L.W. Leroy (1948, 1952) collected worldwide records of the earliest occurrence of Orbulina universa. Assuming synchroneity of these records, his results indicated correlation of the so-called Upper Oligocene of the Antillean-South American region with the Lower Miocene of the Mediterranean region. This was the first positive step towards the downward revision of the Oligocene/ Miocene boundary now generally accepted in tropical America.

At the World Petroleum Congress in 1951 T.F. Grimsdale offered a summarized correlation of the ranges of planktonic foraminifera in the Gulf of Mexico and Caribbean area and in the Middle East. His results were expressed on a chart which demonstrated close parallelism in the order of appearance and extinction of species throughout the Tertiary of both areas. Data for the Eocene were more precise than for the Oligocene and Miocene, but the chart embodied a suggestion that the species then treated as Oligocene in the American region first appeared within the Miocene of the Middle East.

Grimsdale’s paper was compressed, with few annotations and no source references, leaving the way open for carefully documented studies. An early example of such work was the successful demonstration by M. Rey (1954) of direct matching of planktonic suites in Morocco with assemblages described from various Caribbean formations, one case being an assemblage typical of the G. dissimilis zone as described in Trinidad and Hispaniola. Similarly papers by Blow (1957) on Sicily and Malta and by Hagn (1958) on Greece have documented planktonic faunas representative of other American zones.

In a more ambitious paper C.W. Drooger (1956-b) made an attempt to correlate a widespread series of Mediterranean Oligo-Miocene planktonic assemblages with their American counterparts. This was a valiant effort but, unfortunately, the flood of European and North African data now available has rendered several of Drooger’s age determinations untenable, as demonstrated by Blow (1957), Eames and Clarke (1957), Colom (1958) and the present paper. Apparently he relied too heavily on the Miogypsinidae as age-indices without paying due regard to other criteria.

Nevertheless Drooger did, very properly, attempt to identify diagnostic plankton in the type developments of European stages, and his conclusions regarding these key faunas must be discussed. For the type Rupelian, Aquitanian, Burdigalian and Helvetian his studies were inconclusive because of paleo-ecologic factors unfavorable to the planktonic foraminifera. Regarding the type Tortonian he clearly misinterprets Gianotti (1953) in comparing the fauna to that of the G. fohsi zone. Actually Gianotti (p. 285), 286) records G. menardii and the closely related G. tumida, but no members of the G. fohsi lineage, and the same is true of the underlying Helvetian (Ruscelli, 1953). This Vindobonian of the Tortona area can therefore be identified directly with the G. menardii zone of America, a local conclusion in full accord with the regional evidence.

Drooger was clearly misled by the type Vindobonian faunas of the Vienna Basin, as recorded by Marks (1951), Grill (1953) and himself. At first sight the abrupt appearance of Orbulina in the upper («Tortonian») part is suggestive of the G. fohsi zone. Even though Marks listed G. menardii, this unfigured reference might be treated, as elsewhere, as a misidentification of G. praemenardii. However, the anomaly apparently arises from paleogeographic factors. The Helvetian sediments of the Vienna Basin represent a transgression from the north, which accounts for the non-Mediterranean «unusual planktonic fauna, possibly of a provincial nature» noted by Drooger. The Tortonian sediments, in contrast, represent a new transgression from the south, bringing in new faunal elements of a Mediterranean warm-water type (fide Gignoux and others). Orbulina universa, Globigerinoides triloba-group and Globorotalia menardii-group, newcomers to the Vienna Basin in the Tortonian, are acknowledged warm-water indices. Hence it appears probable that the brusque appearance of this fauna is of localized time significance in this special instance, representing overflow from a population already firmly established in the main Mediterranean region farther south.

A paper by W.H. Akers and C.W. Drooger (1957) is mainly concerned with regional correlation in the Gulf Coastal States, but it includes comments on European equivalence. The chronology follows Drooger’s earlier paper and is considered erroneous for the reasons discussed above. The ranges of planktonic species charted as late Helvetian to early Sarmatian should, in the present writer’s opinion, be lowered to the late Aquitanian and Burdigalian interval.

A summarized paper due for publication by H.M. Bolli (in press) offers a transatlantic correlation of the fine zonation now in use in Trinidad. Expressed in terms of the present paper, the three upper zones are dated the same except that the lower G. menardii zone (G. mayeri zone of Bolli, 1957) is placed in the upper Burdigalian, not the Helvetian. The two lower zones are likewise equated by Bolli with the whole Oligocene and part of the Aquitanian, their contact being placed within the Stampian-Chattian interval.


As indicated in the preceding text, continued studies have resulted in a progressive lowering of the accepted Oligocene-Miocene boundary in America. The question is here left open whether the whole G. ciperoensis zone and part of the G. dissimilis zone or only part of the G. ciperoensis zone represents the whole Oligocene. In either case the Oligocene is greatly reduced relative to the early concept that only the G. menardii zone was Miocene.

Eames (1955) goes so far as to suggest complete absence of the Oligocene in Trinidad, where the four lower zones are represented by the Cipero formation. He states that «probably all the Cipero formation is of Lower Miocene age». This statement implies regional absence of the Oligocene, since no post-Eocene American planktonic assemblages are recorded which do not fall in the well documented zonal sequence of Trinidad.

On several grounds the writer feels forced to contest this hypothesis. His studies in several sectors of the American region have led to a belief that sedimentation was essentially continuous up from the Upper Eocene into the G. ciperoensis zone, in which case at least the lower part of that zone must be Oligocene. The evidence for continued deposition is varied and includes

(1) Local lithologic sequences in which no unconformity or significant change of sedimentary type is discernible at the top of the Eocene.

(2) Lithostratigraphic compilations which show no angularity between the Upper Eocene and the G. ciperoensis zone, although marked angularity (i.e. regional unconformity) is apparent at the base of the Upper Eocene and at the base of the overlying G. dissimilis zone.

(3) Microfaunal continuity from the Upper Eocene into the G. ciperoensis zone. This seems indicated by persistence of the bulk of the fauna, marker-species restricted to one unit or the other forming a minor proportion. Still more striking are the evolutionary lineages, for instance in Bulimina, Uvigerina, Operculinoides, Lepidocyclina, and even the planktonic genera, which seem to proceed upwards from the Eocene with no gap in their morphologic development.

(4) The absence of Miogypsinidae but presence of the ancestral Rotalia mexicana-group in the post-Eocene interval (see Barker and Grimsdale, 1937).

(5) Paleogeographic considerations. The sequence of Upper Eocene followed by the G. ciperoensis zone (with the G. ampliapertura subzone at the base) is known in beds representing all marine environments from shallow, almost littoral, to deep, almost abyssal, yet the sequence of planktonic index-species remains constant. This implies that, if there is a time-hiatus in the American sequence, it is equally pronounced in the deep oceanic basins and in the areas peripheral to the land-masses. Such a conclusion is contrary to the normal precepts of paleogeography.


A final brief comment needs to be made on the systematics applied to the planktonic foraminifera in this paper. A simplified classification is employed, the original generic names being used for Globigerina dissimilis, Globigerinoides glomerosus and G. transitorius rather than one of the newer names Globigerinita, Catapsydrax or Tinophodella for the former or Porticulosphaera for the latter. The main reason for this simplification is ease of cross-reference with the Mediterranean literature, but as a stratigrapher the writer dares state that he finds the ever-growing complexity of genera and subspecies (vide Loeblich at al., 1957; Banner and Blow, 1959; et al.) more hindrance than help except where evolutionary relationships are clarified. Hofker (1959) has expressed a biologist’s objections to modern classification of the Globigerinidae.

As regards speciation, in one or two cases a well-known specific name has been employed in preference to a valid but little-used synonym. The most important example is Globigerinoides bisphericus Todd 1954 (not G. sicanus De Stephani 1951, in Plinia (Palermo), vol. 3 (1950-1951), nota 4, p. 9).


The following bibliography contains three categories of reference papers : (a) all works available to the author containing factual data on the distribution of planktonic foraminifera in the Oligo-Miocene of the Mediterranean region; (b) a selected list of works contributing to recognition of the regional validity of the Oligo-Miocene planktonic zonation in America; and (c) a few specific references to special points discussed in the preceding text.

A.G.I.P. Mineraria (1957) : Foraminiferi Padani (terziario e quaternario) : atlante iconografico e distribuzione stratigrafica. Milan.

Akers W.H. (1955) : Some planktonic foraminifera of the American Gulf Coast and suggested correlation with Caribbean Tertiary. Jour. Paleont., vol. 29, p. 646-664.

Akers W.H. and Drooger C.-W. (1957) : Miogypsinids, planktonic foraminifera and Gulf Coast Oligo-Miocene correlations. Amer. Assoc. Petrol. Geol., Bull., vol. 41, p. 656.678.

Ascoli P. (1956) : Microfauna della serie eocenica di Rio Repregoso e della serie oligocenica superiore de Mombisaggio-Mongariolo (Tortona-Alessandria). Riv. Ital. Pal. Strat., vol. 62, n° 3, p. 153-196.

Ascoli P. (1957) : Microfauna del Tortoniano di Mombisaggio e della serie pliocenica di Volpeglino. Ibid., vol. 63, n° 1, p. 3-30.

Banner F.T. and Blow W.-H. (1959) : The classification and stratigraphical distribution of the Globigerinaceae : Part I. Paleontology, vol. 2, pt. 1, p. 1-27.

Bandy O. (1949) : Eocene and Oligocene foraminifera from Little Stave Creek, Clarke County, Alabama. Bull. Amer. Pal., vol. 32, n° 131.

Barker R.W. and Grimsdale T.F. (1937) : Studies of Mexican foraminifera. Ann. Mag. Nat. Hist., ser. 10, vol. 19, p. 161-178.

Beckman J.P. (1953) : Die Foraminiferen der Oceanic Formation (Eocaen-Oligocaen) von Barbados, Kl. Antillen. Ecl. Geol. Helv., vol. 46, n° 2, p. 301-412.

Bermúdez P.J. (1949) : Tertiary foraminifera from the Dominican Republic. Cushman Lab. Foram. Res., Spec. Publ., n° 25.

Bermúdez P.J. (1950) : Contribución al estudio del cenozoico cubano. Soc. Cubana Hist. Nat., Mem., vol. 19, n° 3.

Bertraneau J. and Magné J. (1952) : Le Miocène marin du revers septentrional du bassin du Hodna (Constantine, Algérie). Soc. Géol. France, Bull., série 6, vol. 2, p. 275-281.

Blow W.H. (1956) : Origin and growth of the foraminiferal genus Orbulina. Micropaleontology, vol. 2, p. 57-70.

Blow W.H. (1957) : Transatlantic correlation of Miocene sediments. Ibid., vol. 3, p. 77-79.

Blow W.H. (1959) : Age, correlation and biostratigraphy of the upper Tocuyo (San Lorenzo) and Pozón formations, eastern Falcón, Venezuela. Bull. Amer. Pal., vol. 39, n° 178.

Bolli H.M. (1950): The direction of coiling in the evolution of some Globorotaliidae. Cushman Found. Foram. Res., Contr., vol. 1, p. 82-89.

Bolli H.M. (1951) : Notes on the direction of coiling of rotalid foraminifera. Ibid., vol. 2, p. 139.143.

Bolli H.M. (1954) : Note on Globigerina concinna. Ibid., vol. 5, p. 1-3.

Bolli H.M. (1957-a) : Planktonic foraminifera from the Oligocene-Miocene Cipero and Lengua formations of Trinidad, B.W.I. U.S. Nat. Mus., Bull., n° 215, p. 97-124.

Bolli H.M. (1957-b) Planktonic foraminifera from the Eocene Navet and San Fernando formations of Trinidad, B.W.I. Ibid., p. 155-172.

Bolli H.M. (1959) : Planktonic foraminifera as index fossils in Trinidad, West Indies, and their value for worldwide stratigraphic correlation. Ed. Geol. Helv., vol. 52, n° 2.

Bronnimann P. (1950) : Occurrence and ontogeny of Globigerinatella insueta Cushman and Stainforth from the Oligocene of Trinidad, B.W.I. Cushman Found. Foram. Res., Contr., vol. 1, p. 80-82.

Bronnimann P. (1951) : The genus Orbulina in the Oligo-Miocene of Trinidad. Ibid., vol. 2, p. 131-138.

Busson C. and Magné J. (1955) : Extension du Miocène supérieur du N. du Bassin du Chélif (Algérie occidentale). Soc. Géol. France, C.R., n° 7-8, p. 143.

Colom G. (1951) : Globigerina «ratio » — su distribución y complejidad en los mares terciarios alrededor de la meseta castellana. Inst. Biol. Aplic., Proc., vol. 9, p. 63-82. Madrid.

Colom G. (1952) : Aquitanian-Burdigalian diatom deposits of the North Betic Strait, Spain, Jour. Paleont., vol. 26, p. 867-885.

Colom G. (1954) : Estudio de las biozonas con foraminiferos del Terciario de Alicante. Inst. Geol. Mm. España, Bol., vol. 66, p. 1.279.

Colom G. (1956) : Los foraminiferos del Burdigaliense de Mallorca. Real. Acad. Cien. Artes Barcelona, Mem., vol. 32, n° 5, p. 92-230.

Colom G. (1958) : The age of beds with Miogypsina mediterranea on the island of Majorca. Micropaleontology, vol. 4, p. 347-362.

Colom G. and Gamundi J. (1951): Sobre la extensión e importancia de las «Moronitas» a lo largo de las formaciones aquitano-burdigalienses del estrecho nortbético. Inst. «Lucas Mallada» Invest. Geol., Rev., n° 14, p. 331-385. Madrid.

Colom G. and Muraour P. (1956): Les fossiles du Miocène inférieur (Burdigalien) de Basse-Kabylie. Serv. Carte Géol. Algérie, Bull., no 8, p. 217-250.

Cushman J.A. and Stainforth R.M. (1945) : The foraminifera of the Cipero marl formation of Trinidad, B.W.I. Cushman Lab. Foram. Res., Spec. Publ., no 14.

Dame E. and Magné J. (1956): Sur la position stratigraphique du «Dellysien » et sur l’existence de Miocène supérieur dans la région du Bas Sebaou (Grande Kabylie, Algérie). Serv. Carte Géol. Algérie, Bull., no 8, p. 199.216.

Durand-Delga M. and Magné J. (1958) : Données stratigraphiques et micropaléontologiques sur le Nummulitique de l’Est des cordillères bétiques (Espagne). Rev. Micropaléont., vol. 1, n° 3, p. 155-175.

Dorr J.B. (1933) : New data on correlation of the Lower Oligocene of South and Central America with that of Mexico. Jour. Paleont., vol. 7, p. 432-438.

Drooger C.W. (1954-a) : Miogypsina in northern Italy. Koninkl. Nederl. Akad. Weten., Proc., Ser. B, vol. 57, p. 227-249.

Drooger C.W. (1954-b) : The Oligocene-Miocene boundary on both sides of the Atlantic. Geol. Mag., vol. 91, no 6, p. 514.518.

Drooger C.W. (1955) : The microfauna of the Aquitanian. Burdigalian of south-western France : Part 2, Miogypsinidae. Koninkl. Nederl. Akad. Weten., Verh., vol. 21, n° 2, p. 17-49.

Drooger C.W. (1956-a) : Miogypsina at Puente Viejo, Spain. Ibid., Proc., Ser. V, vol. 59, n° 1, p. 68-72.

Drooger C.W. (1956-b) : Transatlantic correlation of the Oligo-Miocene by means of foraminifera. Micropaleontology, vol. 2, p. 183-192.

Drooger C.W. and Magné J. (1959) : Miogypsinids and planktonic foraminifera of the Algerian Oligocene and Miocene. Micropaleontology, vol. 5, n° 3, p. 273-284.

Eames F.E. (1953) : The Miocene/Oligocene boundary and the use of the term Aquitanian. Geol. Mag., vol. 90, p. 388.392.

Eames F.E. (1954) : The Caribbean «Oligocene». Ibid., vol. 91, p. 326.327.

Eames F.E. (1955) : The Miocene/Oligocene boundary in the Caribbean region. Ibid., vol. 92, p. 86.

Eames F.E. and Clarke W.J. (1957). : The ages of some Miocene and Oligocene foraminifera. Micropaleontology, vol. 3, p. 80.

Emiliani C. (1954): The Oligocene microfaunas of the central part of the northern Apennines. Paleontografica Ital., vol. 48 (n.s., vol. 18), p. 77-184.

Ferasin F. (1954) : Studio micropaleontologico e stratigrafico della campionatura del pozzo AGIP N. 4 di Podenzano (Piacenza). Inst. Geol. Univ. Padova, Mem., vol. 19, p. 1-77.

Ferreira J.M. (1957) : Note micropaleontológica sobre o oligocénico do Seixalinho (Arrábida). Assoc. Portuguesa Progr. Cien., XXIII Congr. Luso-Espanhol, Sec. 4, p. 5-13.

Forti A. (1958) : Studi statistici su una microfauna aquitaniana dell’ Appennino pavese-vogherese. Riv. Ital. Pal. Strat., vol. 64, p. 349-358.

Gianotti A. (1953): Microfauna della eerie tortoniana del Rio Mazzapiedi-Castellania (Tortona-Alessandria). Riv. Ital. Pal. Strat., Mem., n° 6, p. 167-300.

Gianotti A. (1956) : Sulla presenza e sul valore stratigrafico di Globigerinatheka in Sicilia. Riv. Mm. Siciliana, no 40-41, p. 1-12.

Gignoux M. (1950) : Géologie stratigraphique (4th ed.). Paris. Masson et Cie.

Glaessner M.F. (1953): Time-stratigraphy and the Miocene epoch. Geol. Soc. Amer., Bull., vol. 64, p. 647-658.

Grill R. (1953) : Der Flysch, die Waschbergzone und das Jungtertiär um Ernstbrunn (Niederösterreich). Geol. Bund., Jahrb., vol. 96, p. 65-116. Vienna.

Grimsdale T.F. (1951) : Correlation, age determination and the Tertiary pelagic foraminifera. Third World Petroleum Congr., Proc., Sec. I, p. 464-475. Leiden.

Hagn H. (1958) : Mikropaläontologische Untersuchungen an Gesteinen der Insel Kephallinia (Adriatisch-Jonisce Zone Griechenlands). Ann. Géol. Pays Helléniques, vol. 9, p. 89-114. Athens.

Henson F.R.S. (1938) : Stratigraphic correlation by small foraminifera in Palestine and adjoining countries. Geol. Mag., vol. 75, p. 227-233.

Hilly J. and Magné J. (1953): Le Burdigalien de la Kabylie de Collo et du Massif du Cap de Fer (Nord-Constantinois, Algérie). Soc. Hist. Nat. Afrique Nord, Bull., vol. 44, p. 149-163.

Hoffstetter R. (editor) (1956) : Amérique Latine : Antilles (sauf Cuba et Antilles vénézuéliennes). Lexique Stratigraphique International, vol. V, fasc. 2b. Paris.

Hofker J. (1959) : On the splitting of Globigerina. Cushman Found. Forum. Res., Contr., vol. 10, p. 1-9.

Kaasschieter J.P.H. (1955) : The microfauna of the Aquitanian-Burdigalian of southwestern France : Part 3, smaller foraminifera. Koninkl. Nederl. Akad. Weten., Verh., vol. 21, p. 51-99.

Kugler H.G. (1953) : Jurassic to Recent sedimentary environments in Trinidad. Assoc. Suisse Géol. lag. Pétrole, Bull., vol. 20, n° 59, p. 27-60.

Kugler H.G. (1954) : The Miocene/Oligocene boundary in the Caribbean region. Geol. Mag., vol. 91, p. 410-414.

Leroy L.W. (1948) : The foraminifer Orbulina universa, a suggested Middle Tertiary time indicator. Jour. Paleont., vol. 22, p. 500.508.

Leroy L.W. (1952) : Orbulina universa in central Sumatra. Ibid., vol. 26, p. 576.584.

Loeblich A.R. and collaborators (1957) : Studies in foraminifera. U.S. Nat. Mus., Bull., n° 215.

Macfadyen W.A. (1930) : Miocene foraminifera from the Clysmic area of Egypt and Sinai. Geol. Survey Egypt.

Magné J. (1955) : Microfaunes oligocènes de la série a numidienne » de Petite Kabylie (Algérie). Soc. Hist. Nat. Afrique Nord, Bull., vol. 46, p. 269-274.

Magné J. and Tempère C. (1952) : Micropaléontologie de deux bassins néogènes algériens : le Chélif et le Hodna. 19e Congr. Géol. Internat., C.R., Sec. 14, fasc. XVI.

Marks P. (1951) : A revision of the smaller foraminifera from the Miocene of the Vienna Basin. Cushman Found. Foram. Res., Contr., vol. 2, pt. 2.

Martin-Kaye P.H. (1958) : The geology of Carriacou. Bull. Amer. Pal., vol. 38, no 175.

Muir J.M. (1936): Geology of the Tampico region of Mexico. Amer. Assoc. Petr. Geol.

Di Napoli Alliata E. (1952) : Foraminiferi pelagici e facies in Italia. VII Conv. Naz. Metano e Petrolio, Atti., p. 1-34. Palermo.

Di Napoli Alliata E. (1953) : Microfauna della parte superiore della serie oligocenica del Monte San Vito e del Rio Mazzapiedi-Castellania (Tortona-Alessandria). Riv. Ital. Pal. Strat., Mem., no 6, p. 25-98.

Ogniben L. (1958) : Stratigrafia e microfauna del Terziario della zona di Caiazzo (Caserta). Ibid., vol. 64, p. 89-142 ; 199-286.

Perconig E. (1955) : Ricerche stratigrafiche e micropaleontologiche nella regione marchigiana (foglio Fermi). Serv. Geol. Ital., Boll., vol. 77, p. 199-265.

Petters V. and Sarmiento R. (1956) : Oligocene and Lower Miocene biostratigraphy of the Carmen-Zambrano area, Colombia. Micropaleontology, vol. 2, p. 7-35.

Reiss Z. (1957) : Stratigraphic distribution of some Mesozoic and Cainozoic foraminifera of Israel. Israel Geol. Surv., Notes on foraminifera from Israel, no 6.

Renz H.H. (1948) : Stratigraphy and fauna of the Agua Salada group, State of Falcón, Venezuela. Geol. Soc. Amer., Mem., no 32.

Rey M. (1954) : Comparaison des microfaunes du Nummulitique nord-marocain et du Nummulitique du Golfe du Mexique et de la mer des Caraïbes. 19e Congr. Géol. Internat., C.R., fasc. 19, p. 39-60.

Rocha A.T. and Ferreira J.M. (1955) : Estudos dos foraminiferos fosséis as a argiles azuis com Nonionella atlantica,) de Cabo Ruivo. Lisbon Univ, Ciencia, n° 11-12, p. 53.69.

Ruscelli M. (1953) : Microfauna della senie elveziana del Rio Mazzapiedi-Castellania (Tortona.Alessandnia). Riv. Ital. Pal. Strat., Mem., n° 6, p. 99-166.

Ruscelli M. (1956) : La serie aquitaniano-elveziana del Rio Mainia (Asti-Piemonte). Ibid., vol. 62, p. 11-51 63-109.

Rutsch R. (1934) : Pteropoden und Heteropoden aus dem Miocaen von Trinidad, Britisch Westindien. Eclog. Geol. Helv., vol. 27, no 2.

Said R. and Basiouni M.A. (1958) : Miocene foraminifera of Gulf of Suez region, Egypt. Amer. Assoc. Petr. Geol., Bull., vol. 42, p. 1958-1977.

Santini L. (1956) : Studio stratigrafico e micropaleontologico delle formazioni marnoso-arenacee della gonfolite di Coma. Riv. Ital. Pal. Strat., vol. 62, p. 239-264.

Sean A. (1935) : Die stratigraphische Verbreitung den tertiaren Orbitoiden. Eclog. Geol. Helv., vol. 28, no 1.

Sean A. (1948) : Die Geologic den Insel Barbados, B.W.I. (Kleine Antillen) und die Morphogenese der umliegenden marinen Grossformen. Ibid., vol. 40, p. 199-222.

Stainforth R.M. (1948-a) : Applied micropaleontology in coastal Ecuador. Jour. Paleont., vol. 22, p. 113-151.

Stainforth R.M. (1948-b) : Description, correlation and paleo-ecology of Tertiary Cipero marl formation, Trinidad, B.W.I. Amer. Assoc. Par. Geol., Bull., vol. 32, p. 1292-1330.

Stainforth R.M. (1949) : Foraminifera of the upper Tertiary of Egypt. Jour. Paleont., vol. 23, p. 419-422.

Stainforth R.M. (1953) : The basis of Paleogene correlation of Middle America. Soc. Geol. Peru, Bol., vol. 26, p. 247-262.

Stainforth R.M. (in press) : Estado actual de las correlaciones transatlánticas del Oligo-Mioceno por medio de foraminiferos planctónicos. III Congreso Geologico Venezolano, 1959, Mem.

Weiss L. (1955) : Planktonic index foraminifera of northwest Peru. Micropaleontology, vol. 1, p. 301-319.

Woodring W.P. (1957) : Geology and paleontology of Canal Zone and adjoining parts of Panama. U.S. Geol. Surv., Prof. Pap., n° 306-A.

Woodring W.P. (1958) : Geology of Barro Colorado Island, Canal Zone. Smithsonian Misc. Coil., vol. 135, n° 3.

* Creole Petroleum Corporation, Jusepín, Venezuela.