Abstract The study of meandering patterns created by geophysical flows is important for a number of fundamental and applied research topics, including stream and wetland restoration, land management, infrastructure design, oil exploration and production, carbon sequestration, flood-hazard mitigation and planetary palaeoenvironmental reconstructions. This volume, Meandering Streamflows: Patterns and Processes across Landscapes and Scales , contains 13 papers that present field, laboratory and numerical investigations of meandering channels found in distinct environmental and geological contexts and focus on how the interactions of different autogenic and allogenic processes, both in the horizontal and the vertical dimension, affect meander kinematics and the resulting morphology, sedimentology and stratigraphic architecture. In this introductory chapter, we offer an overview of the evolution of scientific research on meandering streams over time, aiming to review and discuss meandering patterns in both fluvial and non-fluvial settings. Additionally, we present a new compilation of data on meander morphological features, drawn from both existing literature and novel sources, encompassing over 8000 meander bends discovered across a diverse array of environments.

Abstract The middle Mesozoic of the southern Junggar Basin is a source of abundant Late Triassic–Jurassic non-marine and Early Jurassic marine–littoral bivalves. The bivalve chronology provides a framework for dating the strata and documents Early Jurassic transgressions and the end-Triassic mass extinction in the Junggar Basin. The first occurrences (FOs) and last occurrences (LOs) of Utschamiella cf. tungussica and Utschamiella cf. obrutschevi lie in the basal upper Rhaetian. The FOs of Ferganoconcha sibirica , Ferganoconcha subcentralis , Unio manasensis , Unio mirabilis and Waagenoperna are at, and the FOs of Margaritifera isfarensis , Tutuella rotunda and Tutuella chachlovi adjoin, the base of the middle Sinemurian. The LOs of Yananoconcha hengshanensis and Waagenoperna are at the Lower–Middle Jurassic boundary. The LOs of Psilunio , Cuneopsis and F . subcentralis are near the Middle–Upper Jurassic boundary. Non-marine bivalves disappeared in the late Rhaetian, due to a sudden Norian–Rhaetian temperature drop. New forms did not return until the Sinemurian, when the climate warmed. The transgressions created low-relief terrestrial environments, in which organisms including bivalves thrived, leading to the formation of large quantities of coal, oil and gas. The Junggar Basin shifted from Arctic to subtropical latitudes in the Northern Hemisphere between the Early and Middle Jurassic.

Abstract We briefly outline the progressive development of approaches to both the characterization and simulation of the hydrogeology of northern European chalk aquifers, which were some of the first in the world to be studied. The volume's scope includes work on water resources and quality, chalk streams and wetland ecosystems, chalks as heat reservoirs for building temperature regulation, sources of groundwater flood risk and impacts of engineering on the subsurface, and diffuse and point-source pollution affecting these aquifers. It excludes hydrocarbon-related studies and those focused on offshore chalk sequences. We briefly outline the current state of knowledge of hydrogeological processes, characterization, assessment and modelling, and the increasingly recognized importance of karst features. The latter were little discussed 20 years ago and are still often neglected. There follows a brief quantitative analysis of publication topics relating to chalk hydrogeology in the scientific literature over the past three decades, which highlights key trends including both the purposes of studies and the methods employed. We present a summary of the topics and contributions within this volume, and conclude by identifying the key issues that need to be addressed in order to ensure the sustainability of our chalk aquifers for the future.

Abstract Water resource management is a major concern in Marquenterre, a maritime plain located in the western part of the Somme department. Water management is particularly indispensable for protecting wetlands in Marquenterre, regulating water usage and avoiding saline intrusion into aquifers. Various approaches including geological modelling and hydrogeological and hydrogeochemical studies were used to prepare a conceptual model of the Marquenterre hydrosystem and to provide better water management in this sector. The conceptual model shows that the chalk aquifer and the various Quaternary deposit aquifers are in hydrogeological continuity. No seawater intrusion has been discovered in groundwater. Salinization discovered at depth is a result of the most recent marine transgressions. Finally, wetlands are primarily supplied by the chalk groundwater or by rainfall. The study results are used to direct policies for surface and subsurface water resource management. The proposed conceptual model may be useful for other coastal aquifers along the English Channel in order to address challenges of managing the chalk groundwater and backshore swamps.

Abstract The UK, and England in particular, is the stronghold for chalk rivers, streams and wetlands in Europe. A number of sites are recognized as being important for nature conservation and have been designated as such under UK and European legislation. However, as the chalk is also an important aquifer for southern and eastern England, there have been significant impacts on these groundwater-dependent ecosystems from abstraction. Chalk rivers and streams have been used for centuries for mills and water meadows, so impacts have not just occurred in recent times. Intensification of agriculture in the twentieth century has added to the pressure by increasing levels of pollution, especially nitrates, with significant levels now being recorded. However, moves have been made to resolve some of these issues, with investigations into the effects of abstraction and options for reducing these impacts, research into the nature of the chalk aquifer so that it can be modelled more accurately, and assessment made of pollution pathways and their timescales. Associated projects have characterized the ecosystems associated with the chalk in more detail, enabling the mechanism for impacts to be better understood. While the extent of impacts is increasingly understood, action is also being taken to reduce their effects and restore chalk ecosystems.

Abstract In Groundwater-Dependent Terrestrial Ecosystems (GWDTEs), atmospheric nitrogen (N) inputs have often been studied in isolation from terrestrial groundwater and surface water inputs. We describe for the first time the development and application of a combined atmospheric and terrestrial N source apportionment methodology, able to identify contributing catchment and N loadings to GWDTEs. We combined all N inputs using a site-specific conceptual model supported by 12 months’ monitoring for a Chalk-fed GWDTE at Newbald Becksies, East Yorkshire. We discuss implications for effective catchment management, wetland protection and development of a source apportionment methodology. Potential sources of nitrate include: atmospheric deposition, mineralization, leaching from agricultural soils, manure heaps, septic tanks, sewer and mains water leakage. Atmospheric deposition was calculated from measurements of ammonia and nitrogen dioxide concentrations together with rainfall inputs of ammonium and nitrate. Quantification of agricultural sources used the FarmScoper modelling tool to estimate nitrate leaching in the groundwater catchment. Comparison between modelled nitrate concentrations in leachate (15–17 mg N l −1 ) and observed groundwater nitrate concentrations (12.3–19.8 mg N l −1 ) are good. The majority of nitrate is leached from arable land. FarmScoper allows mitigation scenarios to be tested, supporting measures to reduce nitrate within a groundwater catchment.

Abstract A threshold-like vegetational change in tropical wetlands occurred in the early Kasimovian (the US Desmoinesian–Missourian boundary) – Event 3. Two earlier significant changes occurred, first in the mid-Moscovian (Atokan–Desmoinesian; ∼Bolsovian–Asturian) – Event 1, and the second in the late Moscovian (mid-Desmoinesian; mid-Asturian) – Event 2. These changes occurred during a time period of dynamic and complex physical change in Euramerican Pangaea driven by changes in polar ice volume and accompanying changes in sea level, atmospheric circulation, rainfall, and temperature. During the Event 3 change, hyperbolized as ‘the Carboniferous rainforest collapse’, lycopsid dominance of (mostly peat) swamps changed to marattialean tree-fern and medullosan pteridosperm dominance, and biodiversity decreased. Event 3 encompassed one glacial–interglacial cycle and included vegetational turnover in other wetland habitats. For several subsequent glacial–interglacial cycles peatland dominance varied, known from palynology, before stabilizing. These vegetational changes likely reflect climatic events driving unidirectional, non-reversible wetland vegetational changes, during cooler, wetter parts of glacial–interglacial cycles. Discussion is complicated by different placements of crucial stratigraphic boundaries, but under the same names, compromising both clear communication and understanding of the literature. Not the least is the floating base of the Cantabrian Substage, together with the position of the Westphalian–Stephanian Stage boundary.

Abstract We present the first analysis of vegetational change in far western equatorial Pangaea (New Mexico, USA) during the Middle–Late Pennsylvanian transition (determined by conodonts and fusulinids) of the Late Paleozoic Ice Age. The study is based on the largest database assembled from this region: 28 of 44 quantitatively analysed floras from 14 of 26 stratigraphic levels. Most sampled floras are ‘mixed’, both below and above the boundary, including both hygromorphic and mesomorphic/xeromorphic taxa. The taxonomic data were recalibrated morphometrically focusing on foliar traits of lamina width and venation. All data were examined using stratigraphic credible intervals, capture–mark–recapture analyses, and resampling analyses. Results indicate no substantive taxonomic turnover across the boundary. This stands in marked contrast to patterns in mid-Pangaean coal basins where there is a large wetland vegetational turnover. However, plant and physical geological data indicate that immediately following the boundary in New Mexico, and for approximately half of the Missourian Stage, floras previously dominated by hygromorphs become overwhelmingly dominated by mesomorphic/xeromorphic taxa. Although expressed differently, the western Pangaean physical and palaeobotanical patterns parallel those from mid-Pangaean coal basins and suggest a widespread environmental change.

Abstract The Middle–Late Pennsylvanian Subperiod was marked by recurrent glacial–interglacial cycles superimposed on a longer-term trend of increasing aridity. Wetland and drought-tolerant floras responded with repeated migrations in the tropics, and a major plant turnover occurred in swamp ecosystems in parts of Euramerica near the Middle–Late Pennsylvanian boundary. However, the corresponding ecological and evolutionary responses of insects and other terrestrial arthropods are poorly understood. Here, we review the record of plant–arthropod interactions and analyse origination and extinction rates of insects during the Middle–Late Pennsylvanian. Although preliminary, plant–arthropod associations broadly persist through the Middle–Late Pennsylvanian boundary, and new damage types and host-plant associations first appear in the Late Pennsylvanian, possibly related to increased availability of accessible vascular and foliar tissues associated with the shift from arborescent lycopsid to tree and seed fern dominance in Euramerican wetlands. Likewise, our analysis of the insect body fossil record does not suggest especially high rates of origination or extinction during this interval. Together, these results suggest that insects did not suffer major extinctions during the Middle–Late Pennsylvanian, despite short- and long-term changes in climate and environmental conditions.

Global sea-level rise increased during the twentieth century from 1.5 to 3.0 mm/yr and is expected to at least double over the next few decades. The Western Louisiana and Texas coast is especially vulnerable to sea-level rise due to low gradients, high subsidence, and depleted sediment supply. This Memoir describes the regional response of coastal environments to variable rates of sea-level rise and sediment supply during Holocene to modern time. It is based on results from more than six decades of research focused on coastal and nearshore stratigraphic records. The results are a wake-up call for those who underestimate the potential magnitude of coastal change over decadal to centennial time scales, with dramatic changes caused by accelerated sea-level rise and diminished sediment supply.