scholarly journals The Eemian stratotype locality at Amersfoort in the central Netherlands: a re-evaluation of old and new data

2000 ◽  
Vol 79 (2-3) ◽  
pp. 197-216 ◽  
Author(s):  
P. Cleveringa ◽  
T. Meijer ◽  
R.J.W. van Leeuwen ◽  
H. de Wolf ◽  
R. Pouwer ◽  
...  
Keyword(s):  
North Sea ◽  
Water Environment ◽  
Type Locality ◽  
Local Conditions ◽  
Sedimentary Environments ◽  
The North ◽  
Sea Bed ◽  
New Information ◽  
Clastic Sediments ◽  
The North Sea

AbstractIn order to obtain a better understanding of the infilling of the Saalian glacial basins during the Eemian, particularly following the recent research in the Amsterdam Basin (Terminal borehole), it was necessary to re-investigate the type locality of the Eemian at Amersfoort. Both published and unpublished data from various biota (diatoms, foraminifers, molluscs, ostracods, pollen) provide new information on the changing sedimentary environments during the Eemian. Although the organic and clastic sediments of the infilling represent nearly all the pollen zones, the sedimentary sequence at Amersfoort is discontinuous: four breaks at least are recognised at the type locality.The successive sedimentary environments and the breaks in the record are linked with the transgression of the Eemian sea, the topographic position at the margin of an ice-pushed ridge, and the changes in hydrodynamic conditions. Local conditions, such as a sandy sea bed, shallow water and a reduced water exchange near the North Sea margin, influenced the salinity of the basin. Rib counts of Cerastoderma edule shells indicate a higher salinity at the end of the Taxus (E4b) and the beginning of the Carpinus (E5) zones than that present in the modern North Sea. Local conditions were responsible for the higher salinity following the climate optimum.During the Abies phase (the later part of regional pollen zone E5), the sea level had already fallen. The change from eu-trophic peat growth (with Alnus and Salix) to an oligotrophic Ericaceae/Sphagnum community at the end of the Eemian resulted from the change from a marine to a fresh-water environment, probably coherent with a deterioration of the climate.

The Thirty-Ninth Thomas Lowe Gray Lecture: Offshore Drilling, with Particular Reference to the North Sea and the ‘Sea Quest’

1966 ◽  
Vol 181 (1) ◽  
pp. 848-875 ◽  
Author(s):  
R. G. S. Avery
Keyword(s):  
North Sea ◽  
Essential Factor ◽  
Safety Equipment ◽  
Offshore Drilling ◽  
Advantages And Disadvantages ◽  
The North ◽  
Drilling Equipment ◽  
Sea Bed ◽  
Weight Problems ◽  
The North Sea

The origins of offshore drilling work and the development of structures used at sea are traced. Comparison of the various types illustrates the advantages and disadvantages of each. Tables show the numbers in operation, being built, and the apparent liability of each type to damage. Typical bore-hole structures are illustrated, the need for undersea well-heads explained and their development into a sea-bed completion is discussed. Much more research is necessary before this can be considered a practical proposition. The design of drilling barge equipment is compared with typical land rigs and the development of drilling equipment, including the sophisticated electric drive and turbo-drill, discussed. Rigs in various types of barge are compared. Fire precautions and other safety equipment are described. The problems associated with control by the driller lead to complications of motive power layout. The lecture describes in some detail the design of the semi-submersible drilling barge Sea Quest, illustrates the weight problems and their effect on floating stability and indicates the need for management decisions on the degree of resistance to damage. This is measured by the variable deck load of drilling equipment that can be held on board and the degree of weather deterioration that can be tolerated before disengaging the drill from the hole. The need for, and extent of, diving is discussed, with some comparison between diving vehicles. Weather too is an essential factor of work in the North Sea and both pre-surveys and day-to-day reporting are described.

scholarly journals Observations on herring spawning and larval distribution in the Firth of Clyde in 1958

1959 ◽  
Vol 38 (3) ◽  
pp. 445-453 ◽  
Author(s):  
B. B. Parrish ◽  
A. Saville ◽  
R. E. Craig ◽  
I. G. Baxter ◽  
R. Priestley
Keyword(s):  
North Sea ◽  
Predatory Fish ◽  
Hatching Rate ◽  
Atlantic Herring ◽  
The North ◽  
Larval Distribution ◽  
Sea Bed ◽  
The North Sea ◽  
Newly Hatched Larvae ◽  
The Relationship

Apart from the extensive egg surveys carried out by Norwegian workers (Runnstrom, 1941) most of the investigations on the spawning of the Atlantic Herring have depended on studies of the distribution of the spawning fish, on captures of newly hatched larvae, and on records of the occurrence of herring eggs in the stomachs of predatory fish species (principally haddock). With the exception of recent observations by Bolster and Bridger (1957), attempts to sample egg concentrations quantitatively in the North Sea and neighbouring areas have usually proved abortive. In consequence little is known of the distribution and density of eggs on the spawning grounds, their percentage fertilization, mortality during the egg stage, hatching rate, and the relationship between the distribution of eggs and the nature of the sea-bed.

A series of North Sea benthos surveys with trawl and headline camera

1982 ◽  
Vol 62 (2) ◽  
pp. 297-313 ◽  
Author(s):  
M. F. Dyer ◽  
W. G. Fry ◽  
P. D. Fry ◽  
G. J. Cranmer
Keyword(s):  
North Sea ◽  
Local Population ◽  
Demersal Fish ◽  
Population Densities ◽  
The North ◽  
Sea Bed ◽  
Successful Series ◽  
The North Sea

During a series of North Sea demersal fish surveys, a headline camera was used to photograph the sea-bed at intervals of 1 min, throughout the duration of 60 min trawls. A successful series of underwater photographs were obtained at 119 stations throughout the North Sea. In addition, the benthos caught at 317 stations was recorded.A total of ca. 30 species could be identified on the underwater photographs, and of these ten species were sufficiently common or locally abundant for estimates of local population densities to be made. Distributions throughout the North Sea based on specimens trawled and specimens photographed were compared.

The Orography of the North Sea Bed

1935 ◽  
Vol 86 (4) ◽  
pp. 334 ◽  
Author(s):  
R. G. Lewis
Keyword(s):  
North Sea ◽  
The North ◽  
Sea Bed ◽  
The North Sea

Doggerland: a Speculative Survey

1998 ◽  
Vol 64 ◽  
pp. 45-81 ◽  
Author(s):  
B.J. Coles
Keyword(s):  
North Sea ◽  
Human Occupation ◽  
River Systems ◽  
The North ◽  
Geological Surveys ◽  
Geological Processes ◽  
Sea Bed ◽  
The North Sea

Archaeologists tend to refer to the land that once existed between Britain and the continent as a landbridge. It was, however, a landscape as habitable as neighbouring regions, and here called Doggerland to emphasise its availability for settlement by prehistoric peoples. Evidence from the Geological Surveys undertaken by countries bordering the North Sea Basin, together with allied research, is drawn together to provide an overview of the possibilities. A range of interacting geological processes implies that the present-day relief of the North Sea bed does not provide a sound guide to the relief of the former landscape, nor to the chronology and character of its submergence. A series of maps accompanies the text to provide a speculative reconstruction of the topography, river systems, coastline, vegetation, fauna, and human occupation of Doggerland from the Devensian/Weichselian maximum to the beginnings of the Neolithic.

Precipitation and flocculation of spherical nano-silica in North Sea chalk

Clay Minerals ◽  
2000 ◽  
Vol 35 (1) ◽  
pp. 175-184 ◽  
Author(s):  
F. Jakobsen ◽  
H. Lindgreen ◽  
N. Springer
Keyword(s):  
North Sea ◽  
Water Environment ◽  
Free Water ◽  
Water Phase ◽  
Spherical Particles ◽  
Force Microscopy ◽  
The North ◽  
Atomic Force ◽  
The North Sea ◽  
Nano Size

AbstractIn the Maastrichtian-Danian chalk in the North Sea, discrete intervals, appearing as normal white chalk, contain up to 60% α-quartz <2 μm in size. Atomic force microscopy (AFM) reveals that the particles are of nm size, appearing as spherical particles and aggregates. Similar particles consisting of opal-CT were found in surface exposures of chalk in Denmark. Two new abiogenic pathways of silica formation in chalk are proposed. The first model proposes that SiO2 nano-size particles and aggregates precipitated and flocculated in the free-water phase as opal and were diagenetically transformed from opal-CT at low temperature to α-quartz at elevated temperature. In the second model, the dominance of radiolarians in the deep-water environment of the North Sea resulted in low dissolution supply with subsequent precipitation and flocculation of nano-size α-quartz particles. In the shallower water of the shelf environment of the present onshore chalk, the abundance of sponges and their dissolution supplied enough Si to precipitate opal-CT in the free-water phase.

Local and global: Seafaring communities in the North Sea area, c. 1600–2000

2015 ◽  
Vol 27 (4) ◽  
pp. 629-646 ◽  
Author(s):  
Karel Davids
Keyword(s):  
Twentieth Century ◽  
North Sea ◽  
Small Towns ◽  
Substantial Part ◽  
Local Conditions ◽  
The North ◽  
The First World War ◽  
The North Sea ◽  
Late Twentieth ◽  
Sea Area

A seafaring community is a village, a small town or a neighbourhood where a substantial part of the population earns its livelihood wholly or partly by work at sea or is directly dependent on seafaring. A seafaring community can arise because an established population at a particular locality increasingly takes up seafaring, or it can be created by the settlement of a sizeable number of seafaring immigrants. The former type of community might be called ‘endogenous’, the latter one ‘exogenous’. This essay analyses in what respect seafaring communities of these two types (or mixtures between them) in the North Sea area changed over time and in what ways these changes were connected to larger, transnational processes or to local conditions. It examines three periods of great transformation: the seventeenth and early eighteenth centuries; the period between about 1850 and the First World War; and the last decades of the twentieth century. The story of endogenous seafaring communities in the North Sea area differed from the story of exogenous communities in many ways. While seafaring communities in villages and small towns vanished in one region and emerged in another, social differentiation within communities increased as well, with shipmasters organising separately from common seamen; eventually, this type of seafaring community disappeared in the late twentieth century. Seafaring communities in big port cities, by contrast, thanks to immigration, continued to exist, although this category, too, has seen shifts in geography in the last 150 years, notably from Amsterdam and London to Rotterdam and Hamburg; moreover, the origin of immigrant seamen vastly changed. This article offers several explanations for these changes and variations.

scholarly journals North Sea palaeogeographical reconstructions for the last 1 Ma

2014 ◽  
Vol 93 (1-2) ◽  
pp. 7-29 ◽  
Author(s):  
K.M. Cohen ◽  
P.L. Gibbard ◽  
H.J.T. Weerts
Keyword(s):  
North Sea ◽  
Large Scale ◽  
Middle Pleistocene ◽  
Glacial Cycle ◽  
Last Interglacial ◽  
Sedimentary Environments ◽  
The North ◽  
Basin Scale ◽  
The North Sea ◽  
Cyclic Changes

AbstractThe landscape evolution of the southern North Sea basin is complex and has left a geographically varying record of marine, lacustrine, fluvial and glacial sedimentation and erosion. Quaternary climatic history, which importantly included glaciation, combined with tectonics gave rise to cyclic and non-cyclic changes of sedimentation and erosion patterns. Large-scale landscape reorganisations left strong imprints in the preserved record, and are important for the detail that palaeogeographical reconstructions for the North Sea area can achieve. In the spirit of the North Sea Prehistory Research and Management Framework (NSPRMF; Peeters et al., 2009), this paper provides background geological information regarding the North Sea. It summarises current stratigraphical and chronological frameworks and provides an overview of sedimentary environments. As we go back in time, the understanding of Quaternary palaeo-environmental evolution in the North Sea basin during the last 1 million years becomes decreasingly accurate, with degree of preservation and accuracy of age control equally important controls. Comparing palaeogeographical reconstructions for the Middle Pleistocene, the last interglacial-glacial cycle and the period following the Last Glacial Maximum illustrates this. More importantly, a series of palaeogeographical maps provide an account of basin-scale landscape change, which provides an overall framework for comparing landscape situations through time.

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