Scale-dependent perspectives on the geomorphology and evolution of beachdune systems

Despite widespread recognition that landforms are complex Earth systems with process-response linkages that span temporal scales from seconds to millennia and spatial scales from sand grains to landscapes, research that integrates knowledge across these scales is fairly uncommon. As a result, understanding of geomorphic systems is often scale-constrained due to a host of methodological, logistical, and theoretical factors that limit the scope of how Earth scientists study landforms and broader landscapes. This paper reviews recent advances in understanding of the geomorphology of beach-dune systems derived from over a decade of collaborative research from Prince Edward Island (PEI), Canada. A comprehensive summary of key findings is provided from short-term experiments embedded within a decade-long monitoring program and a multi-decadal reconstruction of coastal landscape change. Specific attention is paid to the challenges of scale integration and the contextual limitations research at specific spatial and/or temporal scales imposes. A conceptual framework is presented that integrates across key scales of investigation in geomorphology and is grounded in classic ideas in Earth surface sciences on the effectiveness of formative events at different scales. The paper uses this framework to organize the review of this body of research in a 'scale aware' way and, thereby, identifies many new advances in knowledge on the form and function of subaerial beach-dune systems. Finally, the paper offers a synopsis of how greater understanding of the complexities at different scales can be used to inform the development of predictive models, especially those at a temporal scale of decades to centuries, which are most relevant to coastal management issues. Models at this (landform) scale require an understanding of controls that exist at both ‘landscape’ and ‘plot’ scales. Landscape scale controls such as sea level change, regional climate, and the underlying geologic framework essentially provide bounding conditions for independent variables such as winds, waves, water levels, and littoral sediment supply. Similarly, an holistic understanding of the range of processes, feedbacks, and linkages at the finer plot scale is required to inform and verify the assumptions that underly the physical modelling of beach-dune interaction at the landform scale

Ichnofabrics of the Upper Cretaceous fine-grained rocks from the Stołowe Mountains (Sudetes, SW Poland)

Upper Cretaceous fine-grained rocks (the “Plänermergel”) from the Stołowe Mountains are in general strongly bioturbated. The sections studied (180 m thick), located in the southern part of the mountains, are dominated by mudstones, marlstones and siltstones; sandstones, partly unbioturbated, are subordinate. The entire sequence shows a succession of ichnofabrics, which reflects a transgressive-regressive cycle (Cenomanian) and a regressive cycle (lower to middle/upper? Turonian). The trace fossil assemblage contains nine ichnogenera: Asterosoma, Cylindrichnus, Ophiomorpha, Palaeophycus, Phycosiphon, Planolites, Taenidium, Teichichnus, and Thalassinoides. Three basic types of ichnofabrics have been recognized: Ophiomorpha, Thalassinoides and Phycosiphon, all representing fully marine ichnofacies. The first two of these belong to the Cruziana ichnofacies, indicating the offshore zone, and the third one probably to the Zoophycos ichnofacies indicating a quiet shelfal setting below storm wave base

The hydrological flow regime of the rivers in the light of scenarios global climate change

Will the hydrological flow regime of rivers be transformed as a result of global climate change, assuming physical-geographical properties of catchments to be permanent? An answer to this question was sought by way of comparison of the behaviour patterns of a river (its discharge structure in the normal yearly cycle) in real conditions defined on the basis of an observation series from the years 1961-1990 (scenario 0) and in the conditions of the assumed climate change (scenarios GFDL and GISS). The assessment of changes in the regime was made in the quantitative and qualitative terms. Three rivers were chosen for the analysis: the Rega, the Utrata and the Soła, whose catchments lie in the different physical-geographical regions of Poland, in order to gain an insight into the direction and intensity of changes also at a regional scale. The results obtained colaborate the impact of the global climate change on the rivers, both at the mesoscale of Poland and the regional scale. The total annual discharge may change significantly (table 1), either by going up, according to the GISS scenario, or going down, according to the GFDL scenario. The transformation of the discharge rhythm may manifest itself in a shift in the stages of discharge while maintaining its seasonality, and in a change in its magnitude in the particular seasons (e.g., the lowering of the level of base flows and their lengthening, mainly in mountain and lowland rivers, as well as restricted and greatly reduced meltwater floods)

The first geological record of a palaeotsunami on the southern coast of the Baltic Sea, Poland

Tsunami deposits were unknown along the southern coast of the Baltic Sea for a long time. The results of present research provided evidence of high-energy event layers. They occur on the bottom of two hemispherical hollows that are cut into glaciolimnic silt and glaciofluvial sand and gravel from the Late Weichselian Age. The event deposits are represented by poorly sorted marine sand with admixtures of pebbles and allochthonous detritus of biogenic origin: marine, brackish and occasionally freshwater shells and shell debris of molluscs and snails, plant macrofossils from the marine nearshore zone, shreds and lumps of peaty material, gyttja and organogenic silt, lumps of charcoal, wood pieces and tree branches and trunks. All these features are commonly considered indicative of tsunamis. The age of the biogenic detritus found in the tsunami layer ranges from 10 390 to 6 630 cal. yr BP, whereas the oldest gyttja covering the event layers is 6 600 cal. yr BP old. This means that the tsunami occurred between 6 630 and 6 600 cal. yr BP. Various causes of tsunami event have been taken into consideration, including the impact of meteorites within the coastal plain and the littoral zone of the southern Baltic Sea