30 resultados para US Marine Corps


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Algarve Province, Southern Portugal, corresponds in part to a meso-cenozoic basin running along the coast from Cabo S. Vicente to beyond Spanish border. Structurally it is a big monocline plunging southwards much deformed mainly by two East-West longitudinal flexures. Lithostratigraphical and chronostratigraphical studies dealt specially with Jurassic formations. This and the geological mapping of the post-Hercynian sedimentary formations allow us to define the following units: Triassic-Lower Liassic Arenitos de Silves (Silves sandstones sensu P. Choffat, pro parte) - At their base the Silves sandstones (0-150m) are represented mainly by cross-bedded red sandstones. This unit is Upper Triassic (Keuper) in age, on the evidence of some Brachiopoda. Complexo margo-carbonatado de Silves (Silves marl-limestone complex=Silves sandstones sensu P. Choffat, pro parte) (80-200m) overlies the preceding, it may be reported to the Upper Triassic-Hettangian. It consists of a thick pelite-marl-dolomite-limestone series with many intercalations of greenstones. Since no fossils were found it is not possible to conclude whether it is still Hettangian or if it does correspond, in the whole or in part, already to the Sinemurian. Liassic Dolomitos e calcários dolomíticos de Espiche (Espiche dolomite-rocks and dolomitic-limestones) - The usually massive and finely crystalline or saccharoidal dolomites and dolomitic-limestones are the toughest strata of the Algarve margin giving rise to several hills. Its thickness attains in certain points 60 metres at least. Based on geometry and on lithological similarities with the carbonated complex of the northern basin of Tagus river (Peniche, São Pedro de Muel, Quiaios), this formation can be accepted as Sinemurian in age. As it happens with the carbonated complex, here also the first dolomite beds are non-isochronal throughout the region; upper time-limit of the dolomitic facies is either Lower Carixian, Lower Toarcian or even Lower Dogger. The dolomitization is secondary but not much later than sedimentation. However, between Cabo S. Vicente-Vila do Bispo there is evidence of an even later secondary dolomitization related to the regional fault complex. Calcário dolomítico com nódulos de silex da praia de Belixe (Belixe beach dolomitic-limestone with silex nodules) (50-55m) - Ascribed to Lower or Middle Carixian on the basis of Platypleuroceras sp., Metaderoceras sp. nov. and M. gr. Venarense. Calcário cristalino compacto com Protogrammoceras, Fuciniceras e ? Argutarpites de Belixe (Belixe compact crystalline limestone with Protogrammoceras, Fuciniceras and ? Argutarpites) (30m) - Ascribed to Lower Domerian. Middle and Upper Domerian are indicated but by a single specimen of ? Argutarpites. Calcários margosos e margas com Dactylioceras semicelatum e Harpoceratídeos de Armação Nova (Armação Nova marly limestones and marls with D. semicelatum and Harpoceratidae) (25m) -Ascribed to Lower Toarcian. Middle and Upper Toarcian formations are not known in the Algarve. Dogger Calcários oolíticos, c. corálicos, c. pisolíticos, c. calciclásticos, c. dolomíticos e dolomitos de Almadena (Almadena oolitic-limestones, coral-reef-limestones, pisolite-limestones, limeclastic-limestones, dolomitic-limestones and dolomite-rocks) (more than 50 metres), with lagoonal facies. Ascribed to Aalenian-Bathonian-? Callovian. Margas acinzentadas e calcários detríticos com Zoophycos da praia de Mareta (Mareta beach greyish marls and detritical limestones with Zoophycos) (40m) - Pelagic transreef facies with Upper Bajocian and Bathonian ammonites. Calcários margosos e margas da praia de Mareta (Mareta beach pelagic marly-limestones and marls) (110m) - Ascribed to the Callovian on its ammonites. Malm Near Cabo S. Vicente and Sagres the first Upper Jurassic level consists of a yellowish-brown nodular, compact, locally phosphated and ferruginous, sometimes conglomeratic, marly limestone (0,35-1,50m) containing a rich macrofauna, which includes: 1) Callovian forms unknown at Lower Oxfordian; 2) Upper Callovian forms that still survived in Lower and Middle Oxfordian; 3) Lower Oxfordian forms (Mariae and Cordatum Zones); 4) Lower and Middle Oxfordian forms (Mariae to Plicatilis Zone); 5) Middle Oxfordian forms (plicatilis Zone), and some ones appearing in Middle Oxfordian. This condensed deposit is therefore dated from Middle Oxfordian (Plicatilis Zone). The other Upper Jurassic lithostratigraphical units were also mapped but their detailed study is not presented in this work. Correlations between lithostratigraphical and chronostratigraphical scales from P. Choffat, J. Pratsch, C. Palain and from the author are stated. Further correlations are attempted between zonc scales of Carixian-Lower Toarcian and Upper Bajocian-Middle Oxfordian of France, Spain (Asturias, Iberian and Betic Chains), Argel (Orania) and Portugal (northern Tagus basin and Algarve). The study of pyritous fossil assemblages common in Upper Bathonian-Lower Callovian marly levels of the praia da Mareta seems to suggest that these sediments were deposited in a bay or in an almost closed coastal re-entrance virtually without deep water circulation. Although such conditions may occur at any depth one may suppose that these ones actually correspond to an infralittoral neritic environment. The thaphocoenosis collected there are almost entirely composed of nektonic (ammonites, Belemnites) and planktonic (Bositra) faunas. The sedentary (crinoids, brachiopods) or free (sea-urchins, gastropods) epibenthonic forms are very scarce; endobenthonic forms are not known. The palaeontological study of all Nautiloids and Ammonoids of the Liassic and Dogger is presented (except Kosmoceratidae and Perisphinctaceae). Among the thirty one taxa dealt with, one is new (Metaderoceras sp. nov.) and the great majority of the others has been identified for the first time in Algarve. Some others have never been reported before in Portuguese formations. The evolution, during Jurassic times, of the sedimentary basins of the Portuguese plate margin is described. The absence of Cephalopods in the very extensive marly and dolomitic limestones, partly marine, suggests that, during Lower Liassic, palaeogeography underwent no great changes. Dolomitic-limestone with silex nodules from Cabo S. Vicente contain the first ammonites recorded at the base of the Middle Liassic. This facies, although very common in Tethys, is unknown north of the Tagus. The faunal assemblage has a mediterranean to submediterranean character. Comparisons between faunal assemblage" from Algarve with the ones known north of the Tagus show that communications between Boreal Europe and Tethys, virtually non-existent during Lower and Middle Carixian, became very easy during Lower Domerian. In earlier Pliensbachian times two distinct seas were adjacent to the Iberian plate. One, an epicontinental sea with a tethyan fauna, extended southwards from the Meseta margin. Another, was a boreal sea; during its transgressive episodes boreal faunas attained into the basin north of the Tagus. During Middle Carixian and Lower Domerian, owing to simultaneous transgressions, these two seas joined together allowing faunal exchanges along the epicontinental areas which limited the emerging hercynian chains belts. During Liassic, the Algarve belonged undoubtedly to the tethyan submediterranean province. The area north of the Tagus, on the contrary, was a complex realm where subboreal and tethyan affinities alternatively prevailed. In the Algarve the first Middle Jurassic deposits do frequently show lateral thickness reductions as well as unconformities contemporaneous with other generalized disturbances on the sedimentation processes in other parts of Europe. By this time, near Sagres, a barrier reef developed separating lagoonal or ante-reef facies from the transreef pelagic zone. The presence of tethyan fauna, the abundance of Phylloceratidae and the absence of boreal forms allow us to consider the Algarve basin as a submediterranean province. The presence of Callovian pelagic fossiliferous formations in the Loulé area shows that during Middle Jurassic the marl-limestone transreef sedimentation was not confined to the western Algarve. They would extend eastwards where they only can be seen in the core of some anticlines. This is due to the progressive sinking of the meso-cenozoic formations as we proceed towards the South of the Sagres-Algoz-Querença flexure. In the whole of the Peninsule, and as for the Middle Callovian, an important regression can be clearly recognized on the evidence of an erosion surface which strikes obliquely the Middle and Upper Callovian strata. The geographic boundaries of the different faunal provinces are not changed by the presence of many Kosmoceratidae in the phosphate nodules since they are but a minority in comparison with the tethyan forms. An abstract model can be constructed showing that in Western Europe the Kosmoceratidae may have migrated South and westwards through a channel of the sea that linked Paris basin to Poitou and Aquitaine. By migrating between the Iberian meseta and the Armorican massif this fauna reached northern Tagus basin at the beginning of Upper Callovian (Athleta Zone); this south and southwest bound migration would have proceeded, allowing such forms to reach Algarve basin only in latest Callovian times (Lamberti Zone). This migration means that during Middle Jurassic a widely spread North Atlantic sea would exist, flooding the western part of Portugal up to the Poitou.

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This note is concerned with fish remains from Upper Neogene beds at Farol das Lagostas (and nearby quarry of SECIL) and Baía Farta, mainly recovered by the author in 1960, 1961, 1963 and 1967. For further data see ANTUNES, 1964, pp. 213-215. All the forms identified until now (many of them for the first time) are show in «tableau I». Smaller ones are poorly represented. I. benedeni is provisorily accepted as a distinct species, though it may correspond to a dental morphotype that does exist equally in the extant I. oxyrhinchus (see text): therefore I. benedeni from Farol das Lagostas may after all represent only some dental variations that really belong in the form described as I. cf. oxyrhinchus. The presence of Aprionodon and Hypoprion could not be ascertained: Procarcharodon megalodon, Carcharodon carcharias, Isurus benedeni. Galeocerdo cuvieri, and Carcharhinus sp. I and sp. II are specially discussed. The whole fauna does not correspond either to a very shallow and coastal environment, or to deep waters far away from the coast. It clearly points out to warm waters: an acceptable model would be the fauna from the tropical Atlantic between Northern Angola and Senegal-Cape Verde. The age of this fauna was long regarded as Burdigalian. The data formerly presented (ANTUNES, 1963) that allowed us to ascribe a pliocene age to the uppermost Neogene beds of Farol das Lagostas (Neogene III, ANTUNES, 1964) are reviewed and developed in this paper. This view is corroborated by planctonic foraminifera and stratigraphical data which provide further evidence to prove the presence of miocene beds much younger than Burdigalian, and that some deposits previously correlated to this stage have instead a Plio-Pleistocene age. Fish fauna from Farol das Lagostas is very characteristic, with giant P. megalodon in association with C. carcharias (which predominates, and whose stratigraphical distribution is particularly discussed), and with other very advanced forms like the extant tiger shark, G. cuvieri, enormous I. Benedeni, Hemipristis, and Carcharhinus (whose size largely exceeds the maximum observed with miocene material). With the exception of P. megalodon (extinct) all the other forms show very close affinities, or even identity with modern species. Comparisons with very similar faunas from some South African localities that may also have a Pliocene age are also presented.

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This note is concerned with fish remains from upper Neogene beds at Farol das Lagostas (and nearby quarry of SECIL) and Baía Farta, mainly recovered by the author in 1960, 1961, 1963 and 1967. For further data see ANTUNES, 1964, pp. 213-215. All the forms identified until now (many of them for the first time) are show in «tableau I». Smaller ones are poorly represented. I. benedeni is provisorily accepted as a distinct species, though it may correspond to a dental morphotype that does exist equally in the extant I. oxyrhinchus (see text): therefore I. benedeni from Farol das Lagostas may after all represent only some dental variations that really belong in the form described as I. cf. oxyrhinchus. The presence of Aprionodon and Hypoprion could not be ascertained: Procarcharodon megalodon, Carcharodon carcharias, Isurus benedeni. Galeocerdo cuvieri, and Carcharhinus sp. I and sp. II are specially discussed. The whole fauna does not correspond either to a very shallow and coastal environment, or to deep waters far away from the coast. It clearly points out to warm waters: an acceptable model would be the fauna from the tropical Atlantic between Northern Angola and Senegal-Cape Verde. The age of this fauna was long regarded as Burdigalian. The data formerly presented (ANTUNES, 1963) that allowed us to ascribe a pliocene age to the uppermost Neogene beds of Farol das Lagostas (Neogene III, ANTUNES, 1964) are reviewed and developed in this paper. This view is corroborated by planctonic foraminifera and stratigraphical data which provide further evidence to proove the presence of miocene beds much younger than Burdigalian, and that some deposits previously correlated to this stage have instead a Plio-Pleistocene age. Fish fauna from Farol das Lagostas is very characteristic, with giant P. megalodon in association with C. carcharias (which predominates, and whose stratigraphical distribution is particularly discussed), and with other very advanced forms like the extant tiger shark, G. cuvieri, enormous I. Benedeni, Hemipristis, and Carcharhinus (whose size largely exceeds the maximum observed with miocene material). With the exception of P. megalodon (extinct) all the other forms show very close affinities, or even identity with modern species. Comparisons with very similar faunas from some South African localities that may also have a Pliocene age are also presented.

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Improved bromoform concentration as developped at CEPUNL allowed better recovery of small mammals'teeth. At Universidade Católica and Avenida do Uruguay 19 taxa (and a further one with doubt) were recognized. Some are new for the level and for Tagus basin: Lagopsis cadeoti and Melissiodon dominans (1st reference for the genus); Glirudinus modestus (formerly under another name); Armantomys (1st reference for this level); Peridyromys murinus (referred before under another name); Microdyromys legidensis (1st ref. of gen. and sp. for this level); and Heteroxerus rubricati, formerly reported to other species of the same genus. Both localities share the same position viz marine levels under and above. This allows us to correlate them with NS or N6 Blow's zones. Both are distinctly younger-than glauconite in underlying beds about 21 MY old (K-Ar). Small mammals point out to MN3a Neogene subunit. Fauna is much alike Lower Burdigalian ones in Spain, France, Germany and Austria. Terrestrial, maybe steppe forms predominate. Land environment was open, with scant plant cover but not devoid of trees. Peridyromys murinus numerical importance and other data suggest a not so warm climate in correspondance to a minimum temperature event. This is corroborated by associated marine fish fauna entirely without warm water stenotherm species, and by paleobotanical/palynological data. Results are in close agreement with Central Northern Spain. The localities studied here are even more interesting as direct correlations between marine and continental stratigraphical scales are possible.

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New radiocarbon measurements were obtained from middle and upper Paleolithic sites currently under research by the CEPUNL, in well defined stratigraphical situations. With other dates, they yield an approximative chronological global view. Measurement distribution in function of time does not seem to be an hazardous one. In the actual status of our knowledge, this distribution seems to fit in some assemblages: (a) 14000 to 15000 BP, Solutrean; (b) about 20 000 BP, Solutrean; (c) circa 25 000 BP, already Solutrean, and slightly older than 26 000 BP, still Mousterian; (d) between 29 000 and 31 000 BP, Mousterian. The persistance of Mousterian much later than its acknowledged upper limit at about 34 000 BP (and hence the survival of its neanderthalian authors) is demonstrated. For the first time it has been possible to ascertain the upper time limit of the marine 5-8 metres raised beach (Tyrrhenian III) at Serra da Arrábida, and also the age of archaeological sites without stone artifacts, or with uncharacteristic ones. The obtained measurements allow US to correlate localities and sedimentary units with last glaciation events. There seems to have been a distinct correlation between cave and shelter human occupation and events marked by the worsening of climate.

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New radiocarbon measurements were obtained from middle and upper Paleolithic sites currendy under research by the CEPUNL, in well defined stratigraphical situations. With other dates, they yield an approximative chronological global view. Measurement dístribution in function of time does not seem to be an hazardous one. ln the actual status of our knowledge, this distribution seems to fit in some assemblages: (a) 14000 to 15000 BP, Solurrean ; (b) about 20 000 BP, Solurrean ; (e) area 25 000 BP, already Solurrean, and slightly older than 26 000 BP, still Mousterian ; (d) between 29 000 and 31 000 BP, Mousterian. The persistance of Mousterian much later than its acknowledged upper limit at about 34 000 BP (and hence the survival of its neanderthalian authors) is demonstrated. For the first time it has been possible to ascertain the upper time limit of the marine 5-8 metres raised beach (Tyrrhenian III) at Serra da Arrábida, and also the age of archaeological sires wirhout srone arrifacts, or with uncharacteristic ones. The obtained measurements allow us to correlate localities and sedimentary units with last glaciation events. There seems to have been a distinct correlation between cave and shelter human occupation and events marked by the worsening of climate.

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It is very difficult to make paleoclimatic correlations between continental and marine areas, but it is possible with biostratigraphic data. Reliable correlations can be made only between broad periods: between 3.5 and 3 Ma, around 2.4 Ma, until 1.6 Ma and after 1.6 Ma. The arid Mediterranean phases led to the disappearance of the European Villafranchian fauna (1.0 Ma).

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Proceedings of tile 1" R.C.A.N.S. Congress, Lisboa, October 1992

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The section at Cristo Rei shows sandy beds with intercalated clayey lenses (IVb division from the Lisbon Miocene series) that correspond to a major regression event dated from between ca. 17.6 and 17 Ma. They also correspond to a distal position (relatively to the typical fluviatile facies in Lisbon), nearer the basin's axis. Geologic data and paleontological analysis (plant fossils, fishes, crocodilians, land mammals) allow the reconstruction of environments that were represented in the concerned area: estuary with channels and ox-bows; upstream, areas occupied by brackish waters where Gryphaea griphoides banks developped; still farther upstream, freshwaters sided by humid forests and low mountain subtropical forests under warm temperate and rainy conditions, as well as not far away, seasonally dry environments (low density tree or shrub cover, or steppe).

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The present work follows a stratigraphic model for the marine Neogene of Portugal based on the definition of three main marine sedimentary cycles. Conceptually the I, II and III Neogene Cycles can be defined as 2nd order sedimentary sequences with duration ranging from 5 to 8 Ma. The I Neogene Cycle is fully represented only in the Lower Tagus Basin. Ranging from the Early Aquitanian to the Late Burdigalian the I Neogene Cycle testify a transgressive episode in the region of Lisbon and Setúbal Peninsula. Rapid lateral facies variations suggest a shallowmarine basin. This cycle ends with an important Late Burdigalian tectonic compressive event expressed by uplift of the surrounding areas and deformation affecting the Early Miocene deposits of the Arrábida Chain. The II Neogene Cycle includes thick sedimentary sequences covering Paleozoic and Mesozoic formations in the Algarve and Alvalade-Melides regions and it extends as far north as Santarém in the Lower Tagus Basin. Mainly controlled by global eustasy, it was generated by the important positive eustatic trend that characterized the Middle Miocene worldwide to which the Portuguese continental margin acted more or less passively. This cycle ended with a second and the most important compression event starting after the end of the Serravallian affecting the entire Portuguese onshore and shelf areas. This led to an important depositional hiatus of marine sediments for more than 2.5 Ma. During the Early and the Middle Tortonian occurred the clockwise rotation of the Guadalquivir Basin. The thickmarine units deposited afterwards in this basin produced a litostatic load, which seems to have induced subsidence farther west resuming the Neogene marine sedimentation in the Cacela region (Eastern Algarve), during the Late Tortonian. This marks the beginning of the III Neogene Cycle. To the north, in the Sado Basin (Alvalade-Melides region), a similar depositional sequence starts its sedimentation during the Messinian. Further north, in the Pombal-Caldas da Rainha region, marine sedimentation started during the Late Pliocene (Piacenzian). The migration in time, from south to north for the beginning of the marine sedimentation of this cycle is interpreted as reflecting a visco-elastic propagation of the deformation from the Betic chain northwards.

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The sub-fossil fauna from the Late Quaternary marine deposits of Santa Maria is made of more than 50 species of gastropods and bivalves, 19 of them collected recently and for the first time in the northern coast of the island (Lagoinhas Bay). The sub-fossil shells are found in deposits of beach sands, situated 2-3 meters above the present low tide. The carbonated sands from the basal part of the succession yield an autochthonous association of borers dominated by the bivalve Myoforceps aristata (Dillwin, 1817). Upwards, the marine sands contain concentrations of beach drift shells, including well-preserved supratidal and intertidal gastropods, among them a large number of Rissoidae. The bivalve fauna is dominated by disarticulated valves of Ervilia castanea (Montagu, 1803), a small infaunal coloniser of mobile sandy substrates. The composition of the fauna is made essentially of West European species, many of them common to the West Coast of Portugal. However, a few "warm guests" with West African or Caribbean affinities were also found, suggesting a close relation with some of the "Tyrrhenian" warm associations found in the Western Mediterranean.

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Neogene marine mammals are still incompletely known in Portugal. However, a general overview of the geographic and stratigraphic distribution of marine mammal localities in the Miocene of Portugal is already possible. An attempt of correlation between the trends shown by these distributions and the horizontal and vertical environmental shifts is presented. In general, sirenians occur in deposits representing shallow, warm, low energy aquatic environments; while cetaceans are more frequent in more open, deep and temperate marine environments.

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Several Lower and Middle Miocene localities in the Lower Tagus basin near Lisbon yielded Latidae fragmentary remnants. No really decisive character has been recognized that would allow us to state these remnants could surely be ascribed to the genus Lates Cuv. & Val., although we regard this as nearly certain. There are some differences between the Miocene latidae under study and the type species Lates niloticus L. this suggests us to report the concerned remnants to a Lates (?) sp. that could belong to a new, hitherto undescribed species. The occurrence of Lates in fluviatile or lagoonal beds in the Lower Tagus basin Miocene series is not at all surprising under a paleoeciological view point. Even less if account is taken of the presence in the same levels of Siluriforms remnants belonging to Bagridae and Ariidae, two families that are well represented in Africa. Bagrid spines have been found at Quinta das Pedreiras in association with Lates (?) sp. remnants. The Lates (?) sp. discovery in the Lower and Middle Miocene from the Lower Tagus basin results in extending to the West this genus' biogeographic distribution. It is indeed the first discovery of this genus on Europe's Atlantic coasts. No matter which was the geographic origin of these fishes, they had to migrate several hundreds of kilometers through marine waters before entering the Tagus' estuary. The association of Lates (?) sp. remnants with Siluriform ones that have an extant, broad repartition in Africa south of the Sahara points out to an African origin. These thermophyll fishes imigration along the Atlantic coasts from lberian Peninsula probably has been possible owing to a warm climatic event that allowed them to migrate ca. 5 degrees (in latitude) northwards in Burdigalian times.

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Sandpit exploitation near Lisbon allowed collecting of many Miocene, non marine fossils. These sands are part of the mostly marine Miocene series in the Lower Tagus basin. The particularly favourable situation led several researchers to deal with marine-continental correlations. Difficulties often concern methodologic aspects. Some poorly based interpretations exerced a lasting influence. A critical approach is presented. Analysis requires data. Methods based upon models often lead to the temptation of fitting data in order to confirm a priori conclusions, or of mixing up data as if of equal statistic value while they have not at all the same weight. Erroneous interpretations' uncritical repetition for many years "upgraded" them into absolute truth. Another point is endemism vs. europeism. Miocene mammals from Lisbon compared well with corresponding French, contemporaneous taxa, while this was apparently not true for Spanish ones. Too much accent had been put on the endemic character of Spanish, or even regional, mammalian faunas. Nationalist bias and sensationalism also weigh, albeit negatively. Meanwhile nearly all the more evident examples as the rhinoceros Hispanotherium are discredited as Iberian endemisms. Taxa may appear as endemic just because they have not yet been found elsewhere. At least for the medium to large-sized mammals, with their huge geographic distribution, faunal differences depend much more on ecology, climate and environmental conditions. Emphasis on differences may also result from researchers that are often in a precarious situation and need very much to achieve short-term, preferably sensational results. Overvalued differences may mask real similarities. Unethic and not scientific behaviour are further enhanced by "nomina nuda" tricks that may simply be a way to circunvent or cheat the Priority Rule. On the other hand, access to communication networks may present as sensational novelties items that are not new at all, misleading the audience. A new class of "science people" arose, created by the media and not by the value of their real achievements. Discussion is presented on sedimentation processes and discontinuities that are often regarded as absolute precision dating tools, as well as on some geochemical and paleomagnetic interpretations. A very good chronologie frame has been obtained for the basin under study on the basis of an impressive set of data, providing a rather detailed and accurate frame for Miocene marine-continental correlations.