The Storegga tsunami along the Norwegian coast, its age and run up

The statigraphy in 25 coastal lakes shows that most of the Norwegian coastline was impacted by a large tsunami about 7200 ¹⁴C BP. The methodology has been to core a staircase of lake basins above the contemporary sea level in several areas and to map the tsunami deposit to its maximum elevation. The tsunami was identified in the sedimentary record as an erosional unconformity overlain by graded or massive sand with shell fragments, followed by redeposited organic detritus. The greatest recorded runup along the coast (10–11 m above high tide) is found in areas most proximal to the Storegga slide scar on the Norwegian continental slope (Sunnmøre). To the north and south, runup is less, about 6–7 m at Bjugn (250 km north of Sunnmøre) and about 3–5 m in Austrheim (200 km to the south of Sunnmerre). This runup pattern supports the suggestion that the tsunami was generated by the Second Storegga Slide. The recorded runup heights are consistent within and between the investigated areas, and imply that the tsunami wave was not significantly influenced by the local topography, suggesting a very long wave length. The mapped runup estimates are in good agreement with a numerical model of the tsunami generated by the Second Storegga slide, and indicate that the slide was a single major event rather than a set of smaller slides.     

Quaternary magnetostratigraphy in Denmark

Magnetostratigraphical results from various historical, Holocene, Lateglacial and Glacial deposits from Central Jutland, Vendsyssel, the Baltic Sea and Schleswig-Holstein are illustrated and discussed. Although only a few archaeomagnetic case studies have yet been made in Denmark, magnetic datings with accuracies of about ±50 years have been obtained on mediaeval kilns by comparing with a dipole transformed modification of the British archaeomagnetic master curve. Furthermore, a study of the expected east–west orientation of some 330 Romanesque churches in Denmark seem to indicate that about 25% of these churches were magnetically orientated; thus some kind of a magnetic compass may have been in common use in the twelfth century in Denmark. Radiocarbon-dated Holocene lake sediments from lake Skanderborg reveal a distinct pattern of magnetic secular variation with fairly short time constants, which may be useful in magnetostratigraphical correlations of other lake sediments. Also Lateglacial and Early Postglacial sediments from the southern Baltic Sea show systematical magnetic patterns, whereas glacial boulder clay at the bottom shows disturbed directions, obviously moulded by the moving ice. Lateglacial Younger Yoldia clay from North Jutland shows well-developed short periodic swings as well as an extreme declination variation of some 80° to 90°, the so-called 'Nørre Lyngby declination excursion' around 14,000 B.P. A sequence of Older Yoldia clay at the same site furthermore shows significantly low inclination values, the so-called 'Rubjerg low inclination excursion' of an age between 23,000 B.P. and 40,000 B.P. Finally, a well-clustering palaeomagnetic direction from a Weichselian glacial boulder clay from Timmerhorn north of Hamburg is discussed from a hierarchical, statistical point of view.     

Climatic Influence on Morphology and Chemistry of Nine Loess-Profiles,Argentine

Frcdcriksen, Peter: Climatic influence on morphology and chemistry of nine loess profiles, Argentine. Geografisk Tiddskrift 81:16–24. Copenhagen, October, 1981.

Nine profiles developed in loess under a subtropical, continental climate with a pronounced climatic gradient (udic to aridicj were investigated morphologically and chemically in order to elucidate the influence of climate on soil genesis. Four morphological types developed: a) A1A2BtC-soils, b) ABC-soils, c) A(B)C-soils and d) AC-soils. Some variations could be related to the climatic variation, others were better related to texture or to palaeoclimatic (periglacial) conditions.     

The U.K. Regional Research Laboratory Initiative 1987–1991

Abstract

The Economic and Social Research Council in the United Kingdom (U.K.) established the Regional Research Laboratory (RRL) Initiative in 1987 to improve facilities for data processing in the social sciences. The Trial Phase in 1987, which was modestly funded for 18 months, established four trial sites and a National Co-ordinator. The Main Phase of the Initiative, covering 8 laboratories at 10 locations, was launched in October 1988, following submission and selection of proposals. Although not originally planned as such, the initiative became a Geographical Information Systems (GIS) programme because the best proposals came from geographers and planners skilled in the processing of spatial data and because of interest stimulated by the influential Chorley Report. This article reviews the major aims of the Initiative and the progress reached after two years to September 1990. The initiative was highly effective in stimulating new research and development work that had regional, national and international dimensions. Nevertheless, with the exception of one RLL, funding has not been continued beyond 1991 and the initiative has been replaced by a network of University Departments working to continue the academic work with GIS in the U.K. for the next three years.     

PLACE INVADERS: CONSTRUCTING THE NOMADIC THREAT IN ENGLAND*

Over the centuries, the image of nomads threatening sedentary ways of life has been a common pejorative representation. In order to understand what geographies underpin narratives about nomads, I examine how social theory and media representations invoke the image of nomads. Both media and academic representations are buttressed by limited understandings of place and space, framing nomads as the quintessential “place invaders.” Focusing on nomadic Gypsies and Travelers in England provides a contemporary example of this process. British media representations construct nomadic Gypsies and Travelers in England as out‐of‐place and threatening. Deconstructing essentialist geographical conceptions allows us to avoid reproducing the common image of placeless nomads, reveals how people utilize place to render others inferior, and highlights the fact that conflicts between nomadic and sedentary ways of life are not intractable and natural. Adopting a more nuanced understanding of place can challenge the dominant trope of nomads as place invaders.     

Depolarization ratio profiling at several wavelengths in pure Saharan dust during SAMUM 2006

Vertical profiles of the linear particle depolarization ratio of pure dust clouds were measured during the Saharan Mineral Dust Experiment (SAMUM) at Ouarzazate, Morocco (30.9°N, –6.9°E), close to source regions in May–June 2006, with four lidar systems at four wavelengths (355, 532, 710 and 1064 nm). The intercomparison of the lidar systems is accompanied by a discussion of the different calibration methods, including a new, advanced method, and a detailed error analysis. Over the whole SAMUM periode pure dust layers show a mean linear particle depolarization ratio at 532 nm of 0.31, in the range between 0.27 and 0.35, with a mean Ångström exponent (AE, 440–870 nm) of 0.18 (range 0.04–0.34) and still high mean linear particle depolarization ratio between 0.21 and 0.25 during periods with aerosol optical thickness less than 0.1, with a mean AE of 0.76 (range 0.65–1.00), which represents a negative correlation of the linear particle depolarization ratio with the AE. A slight decrease of the linear particle depolarization ratio with wavelength was found between 532 and 1064 nm from 0.31 ± 0.03 to 0.27 ± 0.04.     

Facies architecture and depositional processes of the Holocene–Recent accretionary forced regressive Skagen spit system, Denmark

Spit systems are seldom recognized in the pre‐Quaternary sedimentary record compared to their common occurrence along present‐day coasts and in Quaternary successions. This lack of recognition may partly be due to the lack of widely accepted depositional models describing the facies characteristics of spit systems and their subaqueous platforms in particular. The Skagen spit system is a large active system that began to form 7150 yr bp and from 5500 bp to Recent times it has prograded 4 m year^?1 and accumulated 3·5 × 10⁹ m³ of sand. The spit system provides a unique opportunity for establishing a well‐constrained depositional model because uplift and erosion have made large windows into the preserved facies, while active spit‐forming processes can be examined at the young prograding end of the same system. The depositional model presented here thus builds on excellent outcrops, surface morphology, a well‐defined palaeogeography and detailed C¹⁴ age control supplemented with observations from continuous well cores and profiles obtained by ground‐penetrating radar and transient electromagnetic surveys. The factors that have governed the development of the spit system, such as relative sea‐level change, wave and current climate, tidal range, sediment transport and depositional rates are also well‐understood. The sedimentary facies of the spit system are grouped into four principal units consisting from below of thick storm sand beds, dune and bar‐trough deposits, beach deposits and peat beds. These four units form a coarsening and shallowing upward sand‐dominated succession, up to 32 m thick, which overlies offshore silt with a transition zone and is topped by a diastem overlain by young aeolian dune sand. The sedimentary structures and depositional processes are described in detail and integrated into a depositional model, which is compared to other spit systems and linear shoreface models.     

Stromatolites in the Late Ordovician Eureka Quartzite: implications for microbial growth and preservation in siliciclastic settings

Well-preserved siliciclastic domal stromatolites, up to 2 m wide and 1·5 m high, are found in a 10 to 15 m thick interval within the Late Ordovician Eureka Quartzite of Southern Nevada and Eastern California, USA. These stromatolites appear as either isolated features or patchy clusters that contain more than 70% by volume quartz grains; their association with planar, trough and herringbone cross-bedding suggests that they were formed in an upper shoreface environment with high hydraulic energy. In this environment, sand bars or dunes may have provided localized shelter for initial microbial mat colonization. Biostabilization and early lithification of microbial mats effectively prevented erosion during tidal flushing and storm surges, and the prevalence of translucent quartz sand grains permitted light penetration into the sediment, leading to thick microbial mat accretion and the formation of domal stromatolites. Decimetre-scale to metre-scale stromatolite domes may have served as localized shelter and nucleation sites for further microbial mat colonization, forming patchy stromatolite clusters. Enrichment of iron minerals, including pyrite and hematite, within dark internal laminae of the stromatolites indicates anaerobic mineralization of microbial mats. The occurrence of stromatolites in the Eureka Quartzite provides an example of microbial growth in highly stressed, siliciclastic sedimentary environments, in which microbial communities may have been able to create microenvironments promoting early cementation/lithification essential for the growth and preservation of siliciclastic stromatolites.