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International audience; We evaluate the topographic evolution of the southwestern Alps using Eocene to Pleistocene pollen data combined with existing sedimentological, petrographic and detrital geo-and thermochronological data. We report 32 new pollen analyses from 10 sites completed by an existing dataset of 83 samples from 14 localities situated across the southwestern Alps, including both the pro-and the retro-foreland basins. The presence of microthermic tree pollen (mainly Abies, Picea) indicates that this part of the mountain belt attained elevations over 1900 m as early as the Oligocene. Inferred rapid surface uplift during the mid-Oligocene coincided with a previously documented brief phase of rapid erosional exhumation, when maximum erosion rates may have reached values of up to 1.5–2km/Myr. Slower long-term average exhumation rates of ∼0.3km/Myr since the Late Oligocene helped maintaining the high Alpine topography of the southwestern Alps until today. The relative abundances of meso-microthermic tree pollen (Cathaya, Cedrusand Tsuga) and microthermic tree pollen (Abies, Picea) in the pro-and retro-foreland basin deposits, indicate that the present-day asymmetric topography, with a relatively gentle western flank and steeper eastern flank, was established early in the southwestern Alps, at least since

Aim Our aims were to provide a detailed chronology of past vegetation changes in the tropical mountains of west-central Africa since the Last Glacial Maximum and to discuss montane forest responses to climate change in terms of distribution and biodiversity. Location Lake Bambili, western Cameroon (05°56′ N, 10°14′ E, 2273 m a.s.l.). Methods Fossil pollen was extracted from a long, continuous and well-dated sedimentary sequence extending back 20,000 years. Pollen diversity and evenness estimates were based on rarefaction analysis and on Simpson's (1/D) index. Results Forest was nearly absent from high elevations during the last glacial period. It expanded gradually from 18.4 cal. kyr bp, interrupted only by reversals coincident with the Heinrich 1 (H1) and Younger Dryas (YD) climatic events, and then suddenly collapsed at 3.3 cal. kyr bp. This switch from forest to grassland communities occurred within a time span of three centuries. After 3.3 cal. kyr bp only short and taxon-poor forest phases are recorded, specifically between 2.7 and 1 cal. kyr bp and in recent centuries. Main conclusions Our data indicate that the mountain forests of Cameroon are recent, resulting from plant migrations from various sources from 18.4 cal. kyr bp onwards. Their progressive development closely followed intensification of the Atlantic monsoon, leading to the formation of a dense forest between 11.7 and 3.3 cal. kyr bp. The composition of this forest included the co-occurrence of species whose ranges do not overlap today, and indicates the potential for the development of unique iterations of climax forests through time. These forests appear to be very sensitive to Northern Hemisphere climate change, with phases of expansion/contraction coeval with the boreal deglacial signal, including widely recognized events such as H1, the YD and the 8.2 ka event. From 8.2 cal. kyr bp onwards, the progressive opening of the canopy is likely to reflect increased seasonality in rainfall related to more frequent El Nino/Southern Oscillation (ENSO) events. The final step of this history was the collapse of the montane forest at 3.3 cal. kyr bp. During the last millennium, very severe disruptions have meant that only the most rapidly dispersing species could spread, contributing to a drastic loss of forest biodiversity that has been accentuated by human impact in the last few centuries.

A pollen record from Puyehue area (40°S; 72°W) in the southern Lake District, Chile, indicates that prior to 13,410 14C yr BP (ca. 16,500-15,200 cal yr BP), cold resistant and hygrophilous vegetation, particularly Nothofagus forest and myricaceous vegetation, covered the area. From ca. 15,000 cal yr BP onward, the forest became increasingly dense. Between 10,010 and 7450 14C yr BP (ca. 11,000-8000 cal yr BP), the expansion of Nothofagus obliqua and the spread of grasses suggests the climate became warmer and semi-arid. Lowland deciduous forest (Nothofagus obliqua, Aextoxicon punctatum, Laurelia sempervirens) and Valdivian rainforest (Nothofagus dombeyi, Eucryphia cordifolia, Caldcluvia paniculata, Aextoxicon punctatum, Laureliopsis philippiana) were abundant. During the next two thousand years, stable warm climatic conditions prevailed, and the diversity of the vegetation increased. From 5760 to 1040 14C yr BP (ca. 6500-900 cal yr BP), the North Patagonian rainforest expanded. The presence of Pilgerodendron/Fitzroya, together with Nothofagus forest, suggests that humid conditions prevailed. During the last millennium, human impact intensified and regional vegetation was disturbed, particularly the lowland deciduous forest and Valdivian rainforest. North-Patagonian and subantartic taxa, such as Podocarpus nubigena, Pilgerodendron/Fitzroya, Nothofagus dombeyi type, Austrocedrus chilensis and Drimys winteri, occupied the low and high-altitude parts of the Cordillera. Five hundred years ago, shrub and grasses expanded in the Nothofagus forest, suggesting that forest became more open under cool-cold, and humid climatic conditions. These conditions prevail to the present day.

International audience; The Cap d'Ailly area (Upper Normandy, France) shows several terrestrial–lagoonal sections recording the negative carbon isotope excursion (CIE) associated with the Paleocene–Eocene Thermal Maximum (PETM; 55.8 Ma). A study of the biomarkers and spore/pollen content of the Vasterival section gave com-plementary information on paleofloral changes that occurred around the Paleocene–Eocene (P–E) bound-ary. Aliphatic hydrocarbon fractions revealed a high abundance of vascular plant biomarkers, including tricyclic diterpanes derived from conifers, fernenes derived from ferns and des-A-triterpenes derived from angiosperms. Whereas the vegetation of the depositional environment surroundings seemed alter-nately dominated by ferns and angiosperms (revealed from biomarkers), the regional flora seemed dom-inated strictly by angiosperms such as Juglandaceae (revealed by pollen). Spore/pollen assemblages revealed no major turnover in the paleovegetation, but slight variation in vegetation composition. How-ever, both biomarkers and spores/pollen exhibited two intervals of rapid floral change: the first occurred around the P–E boundary and the second at the top of the strictly terrestrial unit that coincides with a marine transgression. Comparison of the data with published paleoclimatic results, obtained from the same samples, indicated that the first interval of floral change correlates with strong paleohydrological perturbations, whereas the second is linked to an increasing marine influence.

The Paris Basin represents an historical cradle of Palaeogene stratigraphy, where during the nineteenth century the Palaeocene Series and the “Sparnacian Stage” were established. As highlighted by Aubry et al. (2005), whereas the chronostratigraphic connotation of the “Sparnacian Stage” has been controversial since its definition, modern studies of the late Palaeocene–early Eocene interval have revealed that the so-called “Sparnacian” deposits encompass a remarkable and short (~170 kyr) episode of the Cenozoic, the Palaeocene–Eocene Thermal Maximum (PETM, ~55.8–55.6 Ma). Dinoflagellate assemblages from the “Sparnacian” of the Dieppe–Hampshire and Paris basins do not contain the key species Apectodinium augustum, whereas it is present in the northern Belgian Basin Tienen Formation and is coeval there with the CIE and the Apectodinium acme interval. However, our calibration of the Apectodinium acme to the CIE in the Dieppe–Hampshire and Paris basins suggests its attribution to the A. augustum zone. The absence of species A. augustum in the Anglo–Paris Basin may be explained by its restriction to more offshore conditions.

The stratigraphy of the Late Paleocene-Early Eocene has been revised in Avesnois thanks to drillings supporting a geological mapping project. Detailed sampling and analyses were performed along selected drillings, among which sedimentological, mineralogical, chemostratigraphic (δ13Corg), biostratigraphic and palynological data have been obtained. New Mbs/Fms are defined around the Paleocene-Eocene boundary (PEb) and compared to the lithostratigraphic nomenclatures of the Belgian and Paris Basins (Steurbaut, 1998; Aubry et al., 2005). Biostratigraphy based on the study of foraminifera and mammal fauna, palynological content and chemostratigraphy enable correlation to be established between adjacent basins as well as sea level and landscape evolutions to be refined during this critical interval. Upper Thanetian marine units In the AVE 007-drilling (Mormal Forest, Locquignol, between Englefontaine, Landrecies and Maroilles villages), the Coniacian chalk is overlain by a flint conglomerate, whose sandy-clayey matrix contains Thanetian pollen and dinocysts. Widespread in Avesnois and containing often reworked Upper Cretaceous foraminifera and occasionally glauconite, this unit constitutes the Vervins Mb (cf. 'Argile a silex de Vervins' interpreted as a marine conglomerate by Gosselet, 1879). It is often overlain by the Mondrepuis-Bettrechies Sand Mb (cf. 'Sable verts de l'Avesnois'), a thin sandy glauconiferous unit, more clayey and silty westward (cf. 'Tuffeau de Valenciennes' Mb). The three Mbs constitute the Hainaut-Valenciennois Fm and can be correlated to the Belgian Grandglise Mb (upper part of the Hannut Fm) and Bois-Gilles Fm, and to the Paris Basin Châlons-sur-Vesles and Bracheux Fms, all Thanetian in age. Uppermost Paleocene to lowermost Eocene terrestrial units In AVE 007 the Vervins Mb is unconformably overlain by flint gravels (Mormal Mb), then a pyritic sand (Le Quesnoy Sand Mb, cf. 'Sables et Gres du Quesnoy' of Gosselet, 1890), and a lignitic clay (Locquignol Mb), silty and ochreous at the top. All but the top ochreous paleosol contain spores and pollen grains and are devoid of dinocysts, they were thus probably deposited in terrestrial environments. The Carbon Isotope Excursion (CIE) of the PEb begins below the top of the sandy unit and continues in the lignitic clay. The palynological study confirms the Locquignol Mb's earliest Eocene age and allows correlation with the base of the Tienen Fm. To the East of AVE 007 along the Belgium-France border, fluvial fossiliferous gravels and sands have been studied in past sand quarries (Erquelinnes Sand Mb). Above a sharp unconformity, they i) overly Upper Thanetian marine sands (Bois-Gilles Fm, NP9a, then Grandglise Mb, NP8), ii) contain a mammal fauna referred as MP7 in the Mammalian biochronological scale for the European Paleogene (Missiaen et al., 2013) and iii) record the first part of the CIE onset in the basal fossiliferous gravel and marl beds. Three km west of Erquelinnes and toward AVE 007 a few drillings have recognized a sandy and pyritic unit containing resinite fragments, lignite and peat beds (Vieux Reng Mb), overlying a thin basal flint gravel bed (Mormal Mb). These five Mormal, Le Quesnoy, Locquignol, Vieux-Reng and Erquelinnes Sand Mbs form the Sambre Fm. Such fluvial gravels and sands, more or less lignitic, clayey or marly are widespread in northern France and southeastern Belgium. They belong to the so-called Upper "Landenian" and are correlated to the Tienen Fm. In AVE 007, they record the CIE onset marking the PEb and 2.5 m of Upper Paleocene fluvial units, in contrast with Belgian drillings such as Doel and Kallo where a hiatus is present at the PEb. Lower Ypresian hiatus and marine units In AVE 007, a laminated silty unit overlies the Locquignol Mb, contains dinocysts Wetzeliella sp. and agglutinated foraminifera similar to those of the base of the Orchies Clay Mb. Widespread in Avesnois-Valenciennois that marine unit is named Avesnois Mb, it is locally richer in very fine sand, and correlated to the base of the Kortrijk Clay Fm (Ieper Gp). In Avesnois, Sparnacian lagoonal units are absent upon the terrestrial ones described above, again marking a reverse trend when compared with the Belgian and adjacent Basins. This may result from restricted terrestrial environments coinciding with Variscan accidents and structural highs between the Artois anticline and Ardenne Masssif, or to their deposition followed by subsequent erosion prior to the Lower Ypresian marine transgression (cf. sea level drop 2 of Dupuis et al, 2011). Correlations and PETM impact on land All terrestrial units here described fill fluvial channels incised in marine Thanetian and older units such as the Cretaceous or the Variscan basement in Avesnois and Belgium, as already reported elsewhere in northern France (cf. sea level drop 1 of Dupuis et al., 2011). They exhibit locally cross stratification, lignite, flora or vertebrate fauna, for example at Leval, Hoegaarden and Dormaal, and/or are intensively silicified with scarce root or leaf casts. Similar fluvial sediments and silcretes are recognized in the first Sparnacian units and paleogeography of the Paris, Dieppe-Hampshire and London Basins, where the PEb is also present, the CIE being recorded on thicknesses between 3 m (as in AVE 007) to >20 m (as in Sinceny). These features may be regarded now as constant in those Sparnacian landscapes recording the PETM, with very rapid lateral and vertical facies shift, particular paleosols, a few fossiliferous fluvial to lacustrine units and variable deposition rates/sediments preservation. Terrestrial sediments, flora and fauna have been described there before the CIE onset as well, for example at Cobham, Vasterival or Rivecourt (e.g. Smith et al., 2014). Lihons, an intermediate outlier situated between AVE 007 and Sparnacian sites of those basins has further been investigated: marine Thanetian sands are overlain by thin fluvial, lacustrine then lagoonal sediments, the two latter recording the CIE of the PETM on an interval 4 m thick. Here again the basal terrestrial sediments have been deposited before the PEb. In AVE 007, depositional environments are fluvial for the Mormal and Le Quesnoy Mbs, and evolve toward flood plain then palustrine ones for the Locquignol Mb, probably here after the river bed migration, but still recording sporo-pollen fluvial inputs from the hinterland, the whole indicating a rather humid subtropical climate. Compared to the Locquignol Mb, the sporopollinic assemblage of the Mormal and Le Quesnoy Mbs (below the CIE onset) is different, particularly regarding the Normapolles distribution, the Tricolpates, Tricolporates and Monocolpates relative pollen abundances and the pollen ratio of Plicapollis pseudoexcelsus/Juglandaceae. In the three Mbs, rapid vertical variations characterize pollen and fern spores assemblages, with peaks of particular taxa reaching 25% of the total counts, such as for P. pseudoexcelsus, T. platycaryoides, C. dorogensis, P. mcgregorii, T. robustus. They suggest rapid floral changes in the catchment and/or sources changes in the surrounding landscapes compartments for the rivers supplying the fluvial sediments. Resinite particles are irregularly abundant as well as microcharcoals are occasionally abundant, notably slightly before the CIE onset and 1.5 m above it, still within the CIE. The clay mineral assemblage is homogeneous along marine Thanetian units and strongly dominated by Illite-Smectite (IS) mixed layers, whatever the facies, while it is more variable in the marine Ypresian silts (abundant IS, followed by Kaolinite, Illite, Chlorite and Vermiculite). In contrast terrestrial units are dominated by IS followed by Kaolinite, Illite and very rare Chlorite, and no variation is observed across the PEb. Those data would suggest that major environmental changes have regionally begun before the PETM, at the very end of the Paleocene, when terrestrial realm has settled, in relation with a regional uplift. Clay minerals reflect constant reworking of preexisting weathering profiles established upon Cretaceous strata and Variscan basement, while vegetation modifications are subtle and more likely attributable to changes of depositional environments

International audience; The Paleocene-Eocene Thermal Maximum (PETM, 55.8 Ma [1]) is regarded as one of the most rapid global warming of the Cenozoic era, with temperature increase of 4-8°C in about 10-20 ka [2]. Thus, it is often proposed as a potential analogue of future climatic conditions expected in the IPCC screenplays. The PETM is recorded in both marine and continental deposits by an abrupt negative Carbon Isotope Excursion (CIE) associated with other sedimentary and biological anomalies. The consequences of the PETM on terrestrial environments are less documented than in marine ones. This limits our regional- and global-scale understanding of the impact of such a climate change on continents and the associated response of ecosystems. This study focuses on the Vasterival section (Seine- Maritime, Upper Normandy) located in the southern part of the Dieppe-Hampshire Basin, in which the PETM is attested by a negative 13Corg shift in the organic matter (OM), and confirmed by the stratigraphic record in this locality belonging to the Cap d’Ailly composite section [3]. The 2 m thick section, which presents a notably well preserved OM, is mainly constituted by terrestrial sediments from lacustrine to coastal swamp environments, and in which OM-poor clays are followed by OM-rich clays, centimetric lignite beds and clays with roots evidences. The uppermost part of the section is constituted by 50 cm thick lagoonal clay with shell debris that records the Apectodinium acme. Global organic geochemical, palynofacies and isotopic analyses were performed on thirty samples. The total organic carbon of this section is ranging from 0.5 % for OM-poor-clays to 45 % for lignite levels. Hydrogen Index (from 6 to 210 mg HC/g TOC), Oxygen Index (from 80 to 630 mgCO2/g TOC) and Tmax values (from 410 to 430°C) show that the OM is of Type III (terrestrial higher plants), and immature. These results are reinforced by palynofacies observations that show a large amount of ligno- cellulosic phytoclasts in most of the samples. In the uppermost shale the presence of many Apectodinium species would suggest the continuity of the PETM in marine deposits. Thus, the continental deposits would represent a time interval that includes the uppermost Paleocene and the basal part of the PETM. Lipid biomarkers extracted from twenty five samples were quantified and their hydrogen and carbon isotopic composition were determined by GC-irMS. Important changes in palynofacies, biomarker assemblages and compound-specific isotopic data are coincident with the CIE onset interval. This is consistent with an important environmental modification in the Vasterival area during the Early Eocene that could be linked to the PETM climatic change. References [1] Aubry, M. P., Ouda, K., Dupuis, C ., Berggren, W. A., Van Couvering, J A., and the Members of the Working Group on the Paleocene/Eocene Boundary, 2007. The Global Standard Stratotype-section and Point (GSSP) for the base of the Eocene Series in the Dababiya section (Egypt). Episodes 30 (4): 271-286. [2] Zachos, J. C., Pagany, N., Sloan, L., Thomas, E., Billups, K., 2001. Trends, rythms, and aberrations in global climate 65 Ma to Present. Science 292: 686– 693. [3] Dupuis, C., Steurbaut, E., De Coninck, J. and Riveline, J., 1998. The Western Argiles à Lignites facies. In: M. Thiry and C. Dupuis (Eds.), The Paleocene/Eocene boundary in Paris basin: the Sparnacian deposits. Field trip guide. ENSMP Mém. Sc. De la Terre, 34, 60-71.

The Paleocene-Eocene Thermal Maximum (PETM, 55.8 Ma, Aubry et al, 2007) is regarded as one of the most rapid global warming of the Cenozoic era, with temperature increase of 4-8°C in about 10-20 ka. Thus, it is often proposed as a potential analogue of future climatic conditions expected in the screenplays provided by the International Panel on Climate Change (IPCC). The PETM is recorded in both marine and continental deposits by an abrupt negative Carbon Isotope Excursion (CIE) associated with other sedimentary and biological anomalies. The consequences of the PETM in terrestrial environments are less documented than in marine ones. This limits our regional- and global-scale understanding of the impact of such a climate change on continents and the ecosystems response. This study focuses on the Vasterival section (Seine-Maritime, Upper Normandy) located in the southern part of the Dieppe-Hampshire Basin, in which the PETM is recorded in the organic matter (OM) by the negative shift in δ13Corg of the CIE, and confirmed by the stratigraphic record in this locality belonging to the Cap d'Ailly composite section (Dupuis et al., 1998). The 2 m thick section, which presents a notably well preserved OM, is mainly constituted by terrestrial sediments from lacustrine to coastal swamp environments and in which OM-poor clays are followed by OM-rich clays, centimetric lignite beds and clays with roots evidences. The uppermost part of the section is constituted by 50 cm thick lagoonal clay with shell debris that records the Apectodinium acme. Global organic geochemical, palynofacies and isotopic analyses were performed on thirty samples. The total organic carbon of this section is ranging from 0.5 % for OM-poor-clays to 45 % for lignite levels. Lipid biomarkers extracted from twenty five samples were quantified and their hydrogen and carbon isotopic composition were determined by GC-irMS. Important changes in palynofacies, biomarker assemblages and compound-specific isotopic data are coincident with the CIE onset interval. This is consistent with an important environmental modification in the Vasterival area during the Early Eocene that could be linked to the PETM climatic change.

International audience; Biome reconstruction from pollen and plant macrofossil data provides an objective method to reconstruct past vegetation. Biomes for Africa and the Arabian peninsula have been mapped for 6000 years sp and provide a new standard for the evaluation of simulated palaeovegetation distributions. A test using modern pollen data shows the robustness of the biomization method, which is able to predict the major vegetation types with a high confidence level. The application of the procedure to the 6000 years data set (pollen and plant macrofossil analyses) shows systematic differences from the present that are consistent with the numerous previous regional and continental interpretations, while providing a more extensive and more objective basis for such interpretations. Madagascar, eastern, southern and central Africa show only minor changes in terms of biomes, compared to present. Major changes in biome distributions occur north of 15 degrees N, with steppe in many low-elevation sites that are now desert, and temperate xerophytic woods/scrub and warm mixed forest in the Saharan mountains. These shifts in biome distributions, imply significant changes in climate, especially precipitation, between 6000 years and present, reflecting a change in monsoon extent combined with a southward expansion of Mediterranean influence.

Die Grundlage der ypresianischen Ablagerung gibt die plötzliche Erscheinung an von Steinarten des Paläozoikums (Illit und Chlorit) und von Kaolinit, was durch geochemischen Missbildungen und abgeändertes palynologisches Fugenwerk zu erklären ist., The bottom layer of the Ypresian transgression shows the sudden appearance of primitive minerals (illite, chlorite) and of kaolinite, and is characterized by geochemical abnormalities and by modified palynological compounds., La base de la transgression yprésienne est marquée par l'apparition brutale de minéraux argileux primaires (illite et chlorite) et de kaolinite, par des anomalies géochimiques (U, Th, K₂O) et des modifications des assemblages palynologiques., Mercier Monique, Roche Emile, Quinif Yves, Dupuis Christian. Modalités du passage du continental-lagunaire au marin dans l'Yprésien du Bassin de Paris et du Bassin belge à partir des données de la palynologie, de la minéralogie des argiles et de la géochimie des radioéléments. Continental-brakish to marine transition modalities of the Ypresian in the NW of the Paris Basin and of the belgian Basin from the data of the palynology, the clay mineralogy and the radioelements geochemistry. In: Sciences Géologiques. Bulletin, tome 38, n°1, 1985. Palynologie. pp. 61-66.

Die Florenverbreitung und die Entwicklung des Klimas im Laufe der Zeit bringen interessante Beweise zum Problem der Kontinentalverschiebung. Im Karbon bestand ein einheitlicher Kontinent : die Pangaea. Im Mesozoikum bildeten sich verschiedene Blöcke, die bis zur Mittleren Kreide in ziemlich engem Kontakt standen. Dies bezeugen die weltweite Flora im Jura und im .Wealden sowie die Ausbreitung der Angiospermen über alle Kontinente während der Kreidezeit. Die Öffnung des Atlantischen Ozeans im Paläogen erscheint deutlich, da die europäischen und die nordamerikanischen Floren sich seit dem Eozän in verschiedener Richtung entwickelt haben., Палеоботаника, палеоклиматология и материковыи дрейф Исследования по распределению флоры и эволюции климата на протяжении геологического времени дают интересные аргументы в защиту теории материкового дрейфа. В каменноугольный период существовала единая континентальная масса : земля Пангео. В мезозое эта масса распадается на отдельные блоки остающиеся в тесном контакте вплоть до среднего мела. Доказательством последнего служит космополитизм флоры средней юры и вельда, также как и распространение покрытосемянных на всех континентах в меловом периоде. В палеогене, открытие атлантического океана становится явным, на что указывает различная эволюция европейской и североамериканской флоры., The geographical distribution of past floras and the evolution of climates during geological times bring evidence in support of the hypothesis of continental drift. In the Late Paleozoic began the break up of the primitive universal land mass Pangaea into a northern group of continents (Laurasia) and a southern group (Gondwana). In the first one grew a flora in which Coniferae and Pteridospermae (Alethopteris, Neuropteris...) are dominant ; in the other one grew the Glossopteris flora. During the Mesozoic, the different continents of Laurasia and Gondwana remain closely together, which is proved by the cosmopolitan flora of the Jurassic and the progression of Angiosperms in all continents in Mid-Cretaceous time. Floristic provinces appeared in the Late Cretaceous and in the Paleogene periods : the North-Atlantic province, the Siberian-Pacific province and the American-African province. From the Eocene epoch the individual evolutions of european and american floras indicate the opening of the Atlantic ocean., L'étude de la répartition des flores et de l'évolution des climats au cours des temps géologiques apporte des arguments intéressants en faveur de la dérive des continents. Au Carbonifère existait une masse continentale unique : la Pangée. Durant le Mésozoïque, celle-ci va se fractionner en différents blocs qui resteront en contact étroit jusqu'au Crétacé moyen ; en témoignent : la flore cosmopolite du Jurassique et du Wealdien ainsi que l'extension des Angiospermes dans tous les continents au Crétacé. Au Paléogène, l'ouverture de l'Atlantique apparaît nettement comme l'indiquent les évolutions distinctes des flores européenne et nord-américaine à partir de l'Éocène., Roche Emile. Paléobotanique, paléoclimatologie et dérive des continents. In: Sciences Géologiques. Bulletin, tome 27, n°1-2, 1974. Palynologie et dérive des continents. Problèmes posés par les aires pluricontinentales. pp. 9-24.