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Although mountain belts and orogenic plateaus occupy only a limited portion of the Earth's surface (about 4% above 2 km in elevation), they are among the most prominent landscape features with global implications for tectonic deformation, climate, hydrology, and biodiversity. Topographic growth locally modifies the crustal stress field and the locus of active deformation; it re-arranges fluvial networks and atmospheric circulation patterns; it generates highly asymmetric precipitation and marked temperature gradients, and favors the development of diverse ecosystems over geographically limited areas; it thus dramatically impacts biodiversity and the evolution of flora and fauna over geological scales. In recent years, a growing number of studies have tried to investigate the chronology and amplitude of topographic growth in deep time (millions of years), using various field-, laboratory-, and computer-based approaches from a wide range of scientific disciplines. The accuracy and uncertainty associated with these approaches are still being discussed, and studies providing quantitative paleoaltimetry estimates remain rare despite their relevance. Moreover, most quantitative studies so far have concentrated on the youngest and most extensive mountain ranges such as the Himalayas or the American Cordilleras, while the topographic evolution of smaller or much older orogens remain virtually undocumented. This Research Topic contains 11 articles covering a wide range of paleotopography research, from short reviews and perspectives of either established or innovative paleo-topographic approaches, new datasets and syntheses of topographic uplift in well-known and understudied areas, and outlooks on the future development and improvement of paleoaltimetry. Botsyun and Ehlers present recent advances and caveats in high-resolution isotope-based general circulation models (iGCMs) to calibrate stable isotope paleoaltimetry approaches, a growing and dynamic direction for paleotopographic reconstructions. Hren and Ouimet propose a new method to quantify paleotopography based on the isotopic signature of organic molecular biomarkers integrated over river catchments. Following the recent development of triple oxygen analysis, Chamberlain et al. review the application of this method to crystalline rocks and their high potential for paleoaltimetry on the crystalline cores of mountain belts. Ibarra et al. propose to use triple oxygen on lacustrine sediment as a paleoaltimetry tool, which they combine with carbonate clumped isotope data to reconstruct the paleoelevation of Eocene Nevadaplano rocks (North American Cordillera). Gébelin et al. report present-day stream water isotopic lapse rates from the west facing slopes of the equatorial Andes in Ecuador, underscoring that tropical regions can be targeted for future paleoaltimetry studies. Ingalls and Snell provide an exhaustive review of state-of-the-art and emerging tools to investigate the diagenetic alteration of carbonates, a crucial step in stable isotope paleoaltimetry, with an illustration of their impact on Tibetan paleoelevation estimates. McLean and Bershaw investigate the isotopic composition of carbonates while Kukla et al. focus on authigenic clays in paleosols from the John Day Formation (Eocene to Miocene), United States, in the rainshadow of the modern Oregon Cascades, with contrasting interpretations regarding the evolution of regional topography. Beyond stable isotope paleoaltimetry, Montes et al. combine field mapping and detrital zircon geochronology to show that the northern and central Andes were separated between ca. 13–4 Ma by lowlands that connected this region with western Amazonia at ca. 3°N, providing a pathway for biotic exchange. Fox et al. examine the role of fluvial reorganization in the formation of elevated landscapes that resemble uplifted formerly contiguous low-relief landscapes. Taking the southeastern Tibetan highlands as an example, they propose that an interpolated paleosurface across low-relief remnants cannot be used to robustly measure geodynamic processes in space and time. Finally, Heitmann et al. review the recent paleoaltimetry work from the Colorado Plateau and propose several test studies to fill the gap in its uplift history. In summary, this research topic presents new ideas, tools, and results on a wide range of aspects of the paleotopography of mountain and plateau regions around the world. It emphasizes that the future of paleoaltimetry has to be interdisciplinary and combine multiple proxies, considering the numerous uncertainties of individual tools. To increase their robustness and accuracy, the next generation of paleotopography studies will have to incorporate results from a variety of approaches, which is well-illustrated by the array of methods and applications in the eleven articles of this research topic.

In the Miocene , a large wetland system extended from the Andean foothills into western Amazonia. This system has no modern analogue and the driving mechanisms are not yet fully understood. Dynamic topography and Andean uplift are thought to have controlled deposition, with allocyclic base level changes driven by eustasy and orbital forcing also playing a role. In this study we investigate the presumed orbital cyclicity that controlled sediment deposition, while also assessing sediment source and biomes in the Miocene wetland. We do this by integrating lithological, palynological, malacological and geochemical data from the Los Chorros site (Amazon River, Colombia), and by placing our data in a sequence stratigraphic framework. In this sequence biostratigraphic evaluation, the Los Chorros succession is visualized to be composed of a series of flood-fill packages, with a rapid initial flood, marine-influenced conditions at the time of maximum flood, followed by a longer regressive infill phase. Based on the palynology we could differentiate local vegetation, such as palm swamps, from regional origin such as terra firme vegetation (non-flooded Amazonian forest) and Andean montane forest, while from sediment geochemistry we could separate local and regional sediment sources. At the times of flooding, oligotrophic and eutrophic aquatic conditions alternatively characterized the wetland, as is shown by the presence of algae, floating ferns, and mollusc assemblages, while intervening subaquatic debris points to proximal submerged lowlands. In the lower 20 m of the section, marine influences are intermittently evident and shown by short-lived maxima of mangrove pollen, foraminiferal test linings, dinoflagellate cysts , coastal mollusc species, and an episodic decline in terrestrial biomarkers. The upper 5 m of the section is characterized by floodplain forest taxa with a diversity in tropical rain forest taxa and relatively few lacustrine indicators. These marine, mangrove, and lacustrine indicators suggest that the outcrops at Los Chorros represent predominant marine-influenced lacustrine conditions during periods of sea level highstand . The sequence biostratigraphic evaluation further points to eight 41 kyr obliquity-driven depositional cycles, with rapid phases of transgression. Mangrove elements would have colonised within the timeframe of each sea level rise . Based on this relative age constraint and comparison to regional records, deposition likely took place prior to the 13.8 Myr global sea level fall, and most likely during the period just after 14.5 Ma, between Middle Miocene Climatic Optimum (MMCO; 17–14 Ma) and Middle Miocene Climate Transition (MMCT; 14.7–13.8 Ma). Palynological evidence further suggests that to the west, surface elevation ranged from ~1000 up to ~3500 m and hosted protoparamo vegetation, the oldest yet reported and in agreement with predictions from molecular studies. In contrast, contemporaneous sites to the northeast of the wetland consisted of fluvial and cratonic formations, as shown by their Nd and Sr isotopic sediment signature. In summary, our data lead to an improved understanding of how geological and astronomical mechanisms controlled the floral and faunal distribution and controlled sediment deposition in western Amazonia during the middle Miocene. As Miocene conditions strongly contrast with modern western Amazonia, our data provide an important context for the deep time history and evolution of the modern western Amazon rainforest.

The steppe-desert is much older than previously thought, but has evolved substantially from the Paleogene to the present., The origins and development of the arid and highly seasonal steppe-desert biome in Central Asia, the largest of its kind in the world, remain largely unconstrained by existing records. It is unclear how Cenozoic climatic, geological, and biological forces, acting at diverse spatial and temporal scales, shaped Central Asian ecosystems through time. Our synthesis shows that the Central Asian steppe-desert has existed since at least Eocene times but experienced no less than two regime shifts, one at the Eocene–Oligocene Transition and one in the mid-Miocene. These shifts separated three successive “stable states,” each characterized by unique floral and faunal structures. Past responses to disturbance in the Asian steppe-desert imply that modern ecosystems are unlikely to recover their present structures and diversity if forced into a new regime. This is of concern for Asian steppes today, which are being modified for human use and lost to desertification at unprecedented rates.

Over the past decade, species distribution models (SDMs) have become an indispensable item in the ecologist’s toolbox. SDMs, also known as ecological niche models, bioclimatic models, or habitat suitability models, characterize the multivariate ecological space delimiting species’ distributions and project this subset of ecological space back on to geography, resulting in a map of habitat suitability. Although SDMs build on correlations, they offer an important capacity to elucidate the altitudinal zoning on mountains, to forecast the effects of climate change on the risk of plant invasions on to mountains, and to predict the potential of mountains as climate refugia, among many other ecological applications. There are more than 600million digitized and georeferenced collection records currently available through the Global Biodiversity Information Facility (GBIF) portal, which, together with large amounts of spatial data on past, present, and future climatic conditions, quantitative soil conditions, and high‐resolution topographic data, will further increase the popularity and applications of SDMs. In this chapter, we describe the principles and data requirements of SDMs, and provide an introduction to estimating species ranges from collection records and projecting these estimates in space and time.

Mountains, Climate and Biodiversity: A comprehensive and up-to-date synthesis for students and researchers Mountains are topographically complex formations that play a fundamental role in regional and continental-scale climates. They are also cradles to all major river systems and home to unique, and often highly biodiverse and threatened, ecosystems. But how do all these processes tie together to form the patterns of diversity we see today? Written by leading researchers in the fields of geology, biology, climate, and geography, this book explores the relationship between mountain building and climate change, and how these processes shape biodiversity through time and space. •In the first two sections, you will learn about the processes, theory, and methods connecting mountain building and biodiversity •In the third section, you will read compelling examples from around the world exploring the links between mountains, climate and biodiversity •Throughout the 31 peer-reviewed chapters, a non-technical style and synthetic illustrations make this book accessible to a wide audience •A comprehensive glossary summarises the main concepts and terminology Readership: Mountains, Climate and Biodiversity is intended for students and researchers in geosciences, biology and geography. It is specifically compiled for those who are interested in historical biogeography, biodiversity and conservation.

Geodiversity mapping has become an established tool for assessing the value of the abiotic part of the landscape. We present two methods, which have been developed in the mountains of the State of Vorarlberg (Austria), but have a wider application in alpine areas. The first is a region‐wide index‐based mapping of Vorarlberg that is designed with the purpose of generating, in a preliminary evaluation, an inventory of clusters of high geodiversity. The second method comprises detailed geomorphological mapping at a local scale and supports landscape planning and management by identifying potential geoconservation sites. The latter approach also enables the evaluation of the relationship between geodiversity and biotopes. We generated a geodiversity (index) map of Vorarlberg in a GIS showing the spatial distribution of a combination of six abiotic factors (subindices) expressed as numeric values in five classes. Both conventional and unconventional data sets were used, ranging from field‐based geological maps to digital data sets acquired in airborne LiDAR surveys. In this approach, high geodiversity is found more often in areas of combined complex topography and varied geological substrata. The geodiversity map can be used to rapidly assess the occurrence of clusters of high geodiversity, which subsequently can be evaluated in detail using a landform‐based approach. As an example of the latter, we present the case study of a small area near the village of Au in central Vorarlberg, Austria. Using a detailed area‐covering polygon‐based morphogenetic map as the basis for the assessment of the Au West area, the various classes of the legend were weighted and ranked in an automated GIS procedure with four factors: scientific relevance and frequency of occurrence (primary factors) and vulnerability and disturbance (secondary factors). Three levels of importance for geoconservation potential are differentiated (low, medium and high significance) and displayed in a map on which the highly ranked units are identified as potential sites for geoconservation. Comparison of the morphogenetic types and existing biotope data in the case‐study area suggests that most biotopes occur together with specific morphogenetic types. It appears that the distinction between “wet” and “dry” mass‐movement processes is an important factor, together with slope steepness and material properties, for effectively characterizing the natural biotopes.

International audience; Global climate cooling from greenhouse to icehouse conditions occurred across an enigmatic transitional interval during the Eocene epoch characterized by incipient polar ice-sheet formation as well as short-lived warming events, of which the Middle Eocene Climatic Optimum (MECO) is most noticeable. Understanding this critical period requires high-resolution records that are being gathered in marine basins, but are still lacking in the terrestrial realm. Here, we provide a precisely-dated terrestrial record crossing the MECO time interval from the Xining Basin (NW China). We document a rapid aridification step and the onset of obliquity-dominated climate cyclicity indicated by lithofacies and pollen records dated at 40.0 Ma at the base of magnetochron C18n.2n. This shift is concomitant - within error - with the MECO peak warming in Ocean Drilling Program Site 1258 for which we reassessed the magnetostratigraphic age at 40.0 Ma (also at base of magnetochron C18n.2n). The rapidity of the shift observed in the Xining Basin and the region-wide aridification and monsoonal intensification reported around 40 Ma suggests Asian paleoenvironments were responding to global climate changes associated with the MECO. However, the Xining records show only the permanent shift but not the transient peak warming observed in marine MECO records. We thus relate this permanent aridification to occur during the post-MECO cooling. We propose the mechanisms linking global climate to Asian paleoenvironments may be eustatic fluctuations driving the stepwise retreat of the proto-Paratethys epicontinental sea or simply global cooling reducing moisture supply to the continental interior. In any case, Eocene global climate cooling from greenhouse to icehouse conditions seem to have played a primary role in shaping Asian paleoenvironments.

Climate change follows from the interaction between global atmospheric and oceanic processes with regional processes. In this chapter we review which factors determined climate evolution in Amazonia and the Brazilian Northeast and present a recompilation of Neogene palynological and paleobotanical records. These records suggest generally warm and humid conditions throughout this region during the Neogene. The uplift of the Andes, in the western half of South America, created a pattern of intense orographic precipitation in Western Amazonia that derived from humid air masses of Atlantic origin. During this time interval uplift of the Borborema Plateau, in the northern Brazilian Highlands, also formed an orographic barrier that allowed the development of a lush forest on the Atlantic side (Mata Atlantica), while rain shadow on the western flank gave place to the semi-arid Caatinga vegetation. The arid conditions in the Brazilian Northeast were further exacerbated by the evolution of the oceanic current system in the Atlantic, a system that was also responsible for the creation of the Namib Desert. The palynological and paleobotanical data illustrate the long history of Amazonia’s tropical forest, but also the influence of the Andes formation on this region. The limited paleobotanical remains from the Brazilian Northeast tentatively point at longstanding humid conditions that, in the latter part of the Neogene transformed into the predominantly arid conditions that characterize the area at present.

This chapter examines the geological development of the Orinoco and Amazon River basins. It analyzes the evolution of aquatic Amazonian ecosystems from the Late Cretaceous to the Quaternary period and provides and considers the potential impacts on the development of modern Amazonian fish faunas. It provides paleogeographic reconstructions of northern South America from the Oligocene to the Late Miocene based on the geological and paleontological records.

The Amazonian Craton is an old geological feature of Archaean/Proterozoic age that has determined the character of fluvial systems in Amazonia throughout most of its past. This situation radically changed during the Cenozoic, when uplift of the Andes reshaped the relief and drainage patterns of northern South America. Here we review the sedimentary characteristics of Amazonian rivers and compare these with four fluvial depositional settings from the Meso-Cenozoic sedimentary record. These sedimentary units are the Alter do Chão Formation (Brazil, Late Cretaceous-Paleogene), the Petaca Formation (Bolivia, Late Oligocene to Middle Miocene), the Mariñame and Apaporis Sand Units (Colombia, Miocene), and the Iquitos White Sand Unit (Peru, Late Miocene-Pliocene). This review illustrates that the river systems born on the craton share features such as sediment texture and composition, depositional environments and transport directions. Evidence for the diminished role of cratonic fluvial systems and the onset of Neogene Andean uplift can be identified in the sedimentary record by changes in sediment provenance and transport directions. Although the Andean uplift and related processes discontinued the major Amazonian-born fluvial systems it also created new topographic features such as the Iquitos and Fitzcarrald Arches. These newly formed reliefs triggered a new generation of rivers, some of which are presently known as biodiversity hotspots.

The northwestern Amazonian landscape includes most of the representative landscape units that characterize Amazonia, and for this reason it constitutes an excellent place to investigate relationships between the abiotic environment (geology, geomorphology, soils) and biodiversity. In this review we assess these relationships on three temporal/spatial scales. At the macroscale, the geology of this area includes the sub-Andean zone in the west, the Guiana Shield to the north, and the varied Neogene substrate and river valleys. These geological units account for much of the habitat variation that can be linked to species distributions. For instance, observations of different tree species communities in Ecuadorian or Peruvian Amazonia are explained by variations in soils and geological substrate. Mesoscale abiotic heterogeneity is reflected in the spatial configuration of different land units, which create conditions for habitat-specific forest types. Experimental field studies arc needed to compare effects of the abiotic environment' (water and soil nutrients) with those related to dispersal and species interactions. At micro scales, processes in the biotic environment probably contribute most strongly to pattern formation in diversity and composition of floras or plant communities.

The paleontological data presented in this special issue provide a new insight into species migration and radiation in Amazonia during the Miocene. At the time, Amazonia was characterized by a very extensive, long-lived, semi-isolated, freshwater wetland ecosystem that was supplied with water and sediment from the Andes and repeatedly influenced by marine conditions. As a result, the wetland had a fauna of characteristic and unusual species composition, containing marine lineages that adapted to freshwater as well as obligate freshwater species. The marine imprint is particularly well reflected in fish and ostracod faunas. Floodplain and isolated lakes in this Miocene wetland also harbored an abundant and highly diverse endemic mollusc fauna. Of these, only Anticorbula (extant in the heart of Amazonia and coastal Guyana) adapted from marine to freshwater conditions (Vermeij and Wesselingh, 2002). However, the Miocene mollusc fauna was decimated somewhere between the Neogene and Quaternary, though it is not clear why this occurred. As Lundberg et al. (1998) point out, it is likely related to the onset of the Amazon River, because the molluscs were highly specialized to a life in shallow lakes and poorly equipped for channel and floodplain lake environments. This explains why only a very small percentage of Miocene molluscs survived until the Present, specifically, those that inhabited the floodplain lake environment. The lacustrine taxa could not handle the fully fluvial conditions that resulted from a full-blown Amazon River and probably perished in the Late Miocene. Evidence from mollusc and fish migration patterns suggest that during the Early-Middle Miocene, a biogeographic connection existed between Amazonia and areas across the present Eastern Cordillera and Caribbean, as Albert et al. and Wesselingh and Mactosay, respectively, note in this issue. In contrast, the findings by Hulka et al. presented in this issue reveal Middle-Late Miocene marine deposits in Bolivia which further underline the regional extent of these incursions. Although the relation between the Bolivian marine deposits and northwest Amazonia remains uncertain, they illustrate that, whether from the north, west, or south, marine incursions reached central South America. Late Miocene sedimentary sequences in Brazil and Peru (Räsänen et al., 1995; Latrubesse et al., 1997; Campbell et al., 2001) are still debated. Rebata et al. give us insight into sediments along the Marañon River (Peru), which they interpret as marine. Ongoing work by other research groups might in the near future provide further insight into the details of the depositional environments and paleogeography during this time interval. The implications of the 'adaptation by marine lineages to freshwater' scenario for aquatic and terrestrial flora and fauna developments are far reaching, as already has been shown for fishes. A recent paper by Nores (2004) also suggests that the marine incursions may be responsible for dispersion patterns in birds. In addition, Wilkinson et al. provide new models on speciation of freshwater organisms in megafan/river systems. Together with these models, they offer new clues about how diversification may have intensified, along with megafan activation, during the Neogene Andean paroxysm. © 2005 Elsevier Ltd. All rights reserved.