J.C. Woodward

River Basin Sediment Systems: Archives of Environmental Change

The context: fluvial archives of environmental change alluvial systematics. Tectonic forcing: crustal instability and the fluvial record the mass terrace sequence at Maastricht, SE Netherlands - evidence for 200m of late Neogene and Quaternary surface uplift flow in the lower continental crust as a mechanism for the Quaternary uplift of the Rhenish Massif, northwest Europe. Climate forcing: records of Pleistocene and Holocene river behaviour. Geoarchaeological perspectives and the human impact. Modelling and monitoring of sediment fluxes and river channel dynamics.

The glacial history of the Pindus Mountains, Greece

Geomorphological evidence for Pleistocene glaciation has been mapped in the Pindus Mountains of northwest Greece, and the chronology of glaciation in this area has been established through soil profile analysis and U‐series dating of secondary carbonates (calcite) formed within glacial deposits. Three glacial stages are evident in the sedimentological and geomorphological records. The earliest and most extensive recorded glaciation predates 350,000 yr B.P. and was characterized by extensive valley glaciers and ice fields. A more recent glaciation occurred before the last interglacial and was characterized by glaciers that reached midvalley positions. The last phase of glaciation in Greece is recorded by small cirque glacier moraines and relict periglacial rock glaciers. The glacial and periglacial sequence on Mount Tymphi has been used in conjunction with a reference parastratotype, the long lacustrine sequence at Ioannina, to provide a chronostratigraphical framework for cold‐stage deposits in Greece. The three glacial stages are formally defined: the Skamnellian Stage, equivalent to the Elsterian Stage of northern Europe and marine isotope stage (MIS) 12; the Vlasian Stage, equivalent to the late Saalian Stage of northern Europe and MIS 6; and the Tymphian Stage, which is equivalent to the Weichselian/Würmian stages of northern Europe and the Alps, respectively, and MIS 5d‐2. This is the first formalized chronostratigraphical framework based on the glacial record to be established for cold stages in the Mediterranean and provides a new platform for paleoclimatological investigations in the region.

Use of a field based water elutriation system for monitoring the in situ particle size characteristics of fluvial suspended sediment

There is increasing evidence that a substantial proportion of the suspended sediment load transported by many rivers is composed of composite rather than primary particles. In consequence, improved techniques for determining the in situ or effective particle size characteristics of the suspended sediment and the grain size of the primary particles making up the composite particles are required in order to obtain a better understanding of both the transport and fate of such material in fluvial systems and the geochemistry of suspended particulate material. This paper describes a field-based water elutriation apparatus which has been successfully employed to investigate the in situ particle size characteristics of suspended sediment transported by the River Exe in Devon, U.K. The reported procedure allows suspended sediment to be drawn directly from the river channel and hydraulically sorted, without disturbance, into five effective size classes. In addition to providing information on the effective grain size distribution, the approach also enables the absolute grain size composition of each effective size class to be determined.

The fluvial record of climate change

Fluvial landforms and sediments can be used to reconstruct past hydrological conditions over different time scales once allowance has been made for tectonic, base-level and human complications. Field stratigraphic evidence is explored here at three time scales: the later Pleistocene, the Holocene, and the historical and instrumental period. New data from a range of field studies demonstrate that Croll–Milankovitch forcing, Dansgaard–Oeschger and Heinrich events, enhanced monsoon circulation, millennial- to centennial-scale climate variability within the Holocene (probably associated with solar forcing and deep ocean circulation) and flood-event variability in recent centuries can all be discerned in the fluvial record. Although very significant advances have been made in river system and climate change research in recent years, the potential of fluvial palaeohydrology has yet to be fully realized, to the detriment of climatology, public health, resource management and river engineering.

Pleistocene glaciation in the mountains of Greece

This chapter reviews some of the recent literature on glaciation in Greece and presents new data on the age of the glacial deposits on the southern flanks of Mount Tymphi in Northwest Greece. The chapter presents radiometric (uranium-series) ages obtained for glacial sediments in Greece and discusses the wider implications of this new chronostratigraphic framework. Recent work has shown that the mountains of Greece contain evidence for multiple phases of ice build up and decay during the Middle and Late Pleistocene. However, there is still a need for detailed field mapping in many areas to establish the precise spatial extent and style of glacial activity in the Greek mountains. The morphological and sedimentological evidence for glaciation is less extensive and less preserved in Central and Southern Greece. At present, the only glaciated terrain in Greece where detailed field-based mapping and lithostratigraphic assessment have been carried out is on Mount Olympus and the surrounding piedmont zone. However, the absence of a reliable and internally consistent chronology for this work limits its value as a source of palaeoclimatic information and prevents detailed comparison with data from Mount Tymphi and with the long pollen sequences in Greece and other records of proxy climate.

Reach-scale river dynamics moderate the impact of rapid Holocene climate change on floodwater farming in the desert Nile

The relationship between climate change and the development of Old World riverine civilizations is poorly understood because inadequate dating control has hindered effective integration of archaeological, fluvial, and climate records. This paper presents the most comprehensive and robustly dated archaeological and paleoenvironmental data sets yet compiled for the desert Nile. It focuses on the valley floor hinterland of the Kingdom of Kerma (2400–1450 B.C.) in northern Sudan. Kerma emerged as a rival to Egypt during Africa’s first “Dark Age” drought. In contrast to other irrigation-based agriculturists in Egypt and Asia, Kerma flourished during the environmental crisis ca. 2200 B.C. We have studied the stratigraphy and archaeological records of paleochannels across an 80 km reach of the Nile upstream of Kerma using optically stimulated luminescence to date when channels flowed and when they dried up. The dynamics of the local alluvial environment were critical in determining whether climatic fluctuations and changes in river flow represented an opportunity for floodwater farmers (5000–3500 B.C.), a hazard that could be managed (2400–1300 B.C.), or an environmental catastrophe that resulted in settlement abandonment (after 1300 B.C.).

Quaternary glaciation in the Atlas Mountains of North Africa

Glacial and periglacial features, formed during the Quaternary, are present throughout the Atlas Mountains in Morocco and Algeria. Moraines, U-shaped troughs, roche moutonee, riegels and cirques all provide evidence of former glacier occupation in these mountains. At least three discrete glaciations have been identified, the most recent of which occurred during the Soltanian. During the most extensive recorded phase of Pleistocene glaciation, snowlines were lowered to c. 3300 m a.s.l. in the High Atlas. Snowlines were progressively lower from the southwest of the range to the northeast with snowlines of c. 2400–2500 m a.s.l in the Middle Atlas and c. 1900–2100 m a.s.l in the Algerian Tell. This difference can probably be attributed to a precipitation gradient from north to south, with greatest levels over the Mediterranean coastal mountains of the Algerian Tell.

Quaternary glaciation in the Mediterranean mountains: a new synthesis

Abstract The Mediterranean mountains were repeatedly glaciated during the Pleistocene. Glaciers were present in most of the major mountains areas from Morocco in the west to the Black Sea coast of Turkey in the east. Some mountains supported extensive ice caps and ice fields with valley glaciers tens of kilometres long. Other massifs sustained only small-scale ice masses, although this was the exception rather than the norm. Glaciers still exist today and there is evidence that small glaciers were a common sight in many regions during the Little Ice Age. The Mediterranean mountains are important for palaeoclimate research because of their position in the mid-latitudes and sensitivity to changes in the climate regimes of adjacent areas including the North Atlantic. These mountains are also important areas of biodiversity and long-term biological change through the Quaternary ice age. All of this provided challenges and opportunities for Palaeolithic societies. This paper reviews the history of the study of glaciation in the Mediterranean mountains from pioneer nineteenth century observations through to the detailed geomorphological mapping and advanced geochronological datasets of recent times. We also review the current state of knowledge to frame the contributions presented in this volume. Lastly, this new synthesis then identifies outstanding research problems and assesses the prospects for new studies of glaciation in the Mediterranean mountains.

Middle Pleistocene glacier behaviour in the Mediterranean: sedimentological evidence from the Pindus Mountains, Greece

Detailed sedimentological analyses of diamicton sequences in two areas of the Pindus Mountains, Greece, indicate multiple episodes of glacier advance and retreat during cold stages of the Middle-Pleistocene. These glacial sequences represent some of the most southerly in Europe and are important archives of regional and global climate change. The Pindus glaciers were relatively small by world standards and would have been highly responsive to changes in air temperature and precipitation. On Mount Tymphi, at least three phases of glacier advance are recorded within deposits assigned to the Skamnellian Stage (MIS 12). Further north on Mount Smolikas, a thick multiple diamicton sequence records evidence for multiple glacier advances during both the Skamnellian Stage and the Vlasian Stage (MIS 6). These records highlight the dynamic nature of glacier behaviour in the Mediterranean mountains during the Middle Pleistocene and provide new evidence for unstable cold stage climates.

Microplastic contamination of river beds significantly reduced by catchment-wide flooding

Microplastic contamination of the oceans is one of the world’s most pressing environmental concerns. The terrestrial component of the global microplastic budget is not well understood because sources, stores and fluxes are poorly quantified. We report catchment-wide patterns of microplastic contamination, classified by type, size and density, in channel bed sediments at 40 sites across urban, suburban and rural river catchments in northwest England. Microplastic contamination was pervasive on all river channel beds. We found multiple urban contamination hotspots with a maximum microplastic concentration of approximately 517,000 particles m−2. After a period of severe flooding in winter 2015/16, all sites were resampled. Microplastic concentrations had fallen at 28 sites and 18 saw a decrease of one order of magnitude. The flooding exported approximately 70% of the microplastic load stored on these river beds (equivalent to 0.85 ± 0.27 tonnes or 43 ± 14 billion particles) and eradicated microbead contamination at 7 sites. We conclude that microplastic contamination is efficiently flushed from river catchments during flooding.Winter floods flushed out 70% of the microplastic contamination from riverbed sediments in northwest England, according to analyses of sediment samples from 40 rural and urban sites.