The stratigraphy and history of Groenvlei, a South African coastal fen

1959 ◽  
Vol 7 (2) ◽  
pp. 142 ◽  
Author(s):  
ARH Martin
Keyword(s):  
Sea Level ◽  
Marine Diatom ◽  
Maximum Height ◽  
Eastern Basin ◽  
The North ◽  
14C Age ◽  
Eastern Australia ◽  
Main Lake ◽  
Sand Bar ◽  
Marine Mud

Borings on the fen at Groenvlei show that the earliest sediment was a diatomaceous nekron mud in a small freshwater lake. This filled in and fen peat formed over it. Subsequently, marine mud was spread over almost the whole basin, the course of the transgression being followed by diatom analysis. A change in composition of the marine diatom flora, apparently due to an unexplained change of temperature of the sea, is recorded. The marine incursion graded into brackish lagoon stages, towards the end of which conditions were rather unfavourable to diatom growth, followed by increasingly freshwater conditions, during which calcareous muds were laid down. The eastern basin of the lake became more or less separated from the main lake by a sand bar. The calcareous lake mud was overgrown by the latest reedswamp and sedge fen. Radiocarbon dating gave an age of 6870 years for a sample from the upper part of the submerged peat bed at Groenvlei, and a lapse of little under 5000 years before freshwater deposits again occupied the eastern basin of the lake (14C age of gyttja sample, 1905 years). This dating of the Groenvlei transgression is compatible both with the main post-Glacial eustatic rise of sea-level in the North Temperate latitudes, and with similar transgressions on the coasts of south-eastern Australia, New Zealand, and Fuego–Patagonia. The maximum height of the sea-level is considered to have been about 1.5 m higher than at present.

Customs and Traditions of the Isle of Portland Dorset

Antiquity ◽  
1949 ◽  
Vol 23 (91) ◽  
pp. 140-152
Author(s):  
Robert Douch
Keyword(s):  
Sea Level ◽  
Maximum Height ◽  
English Channel ◽  
Maximum Width ◽  
The North ◽  
Solid Block

The Isle of Portland reaches out into the waters of the English Channel. Almost a solid block of stone, it is the most southerly point on the Dorset coast. Its greatest length from north to south is four miles and its maximum width one and a half miles, while its entire circumference is less than nine miles. The north of the island is low-lying, but half a mile inland the ground rises steeply to a maximum height of 496 feet above sea-level at the Verne. From here it slopes away gradually to the southern tip or Bill, 20 feet above sea-level. There has never been a town of Portland and the chief centres of population were originally eight hamlets. Today, three of these, Castletown, Fortuneswell and Chesil have merged to form the main settlement in the north or Underhill, as the district is called, On Tophill three more of the hamlets, Reforne, Easton and Wakeham have similarly run together. Weston and Southwell remain hamlets, while another settlement has grown up around the prison at ‘The Grove’.The ‘Island’ is, in fact, joined to the mainland by the Chesil Beach. But since this pebble bank extends westwards for ten miles before it meets the Dorset coast at Abbotsbury and could be used as a thoroughfare only with the greatest difficulty, the term ‘island’ is no real misnomer. Between Portland and the immediate mainland to the north runs the Fleet, a narrow arm of the sea, wide enough to make the approach across Smallmouth by ferry, before the building of the modern bridge, awkward and, at times, dangerous.

IV.—The Carrara, Massa, and Versilia Marble District

1915 ◽  
Vol 2 (12) ◽  
pp. 554-565
Author(s):  
C. S. Du Riche Preller
Keyword(s):  
Sea Level ◽  
Coarse Grained ◽  
Maximum Height ◽  
The South ◽  
The North ◽  
The Mediterranean ◽  
Apuan Alps ◽  
Marble Industry

The range of the Apuan Alps, commonly called the Carrara Mountains, is an offshoot of the Apennines, trending N.N.W. to S.S.E., parallel to the Mediterranean littoral, from which it rises within a distance of barely four miles to a maximum height of 6,000 feet above sea-level. Exclusive of the outer belt of the more recent strata, the Triassic formation, within which the saccharoidal marble beds are situated, covers about 25 by 13 kilometres or about 130 square miles, of which the marble zone proper represents 64 square miles or about half. The range is bounded on the north by the Aullela valley in the Lunigiana district; on the east by the Serchio valley in the Garfagnana district; and on the south by the Serchio valley in the Province of Lucca. The marble district, whose western part faces the Mediterranean, comprises the three divisions of Carrara, Massa, and the Versilia in the corresponding parallel valleys of the Carrione, Frigido, and Serravezza Rivers. The Versilia division, which forms part of the Province of Lucca, is composed of the Seravezza, Stazzema, and Arni subdivisions, of which the last-named lies on the eastern watershed of the Apuan range. The Versilia division also includes Pietrasanta, Camajore, Massarosa, and the wellknown watering-place of Viareggio, near the last-named of which are situated extensive subaqueous deposits of a peculiarly coarse-grained, sharp macigno sand. These deposits, formed as a delta in a lacustrine expanse by the River Serchio, constitute an important and indispensable adjunct of the marble industry as grinding material for the numerous marble saw-mills in the three parallel valleys already referred to.

scholarly journals Transboundary geophysical mapping of geological elements and salinity distribution critical for the assessment of future sea water intrusion in response to sea level rise

2012 ◽  
Vol 16 (7) ◽  
pp. 1845-1862 ◽  
Author(s):  
F. Jørgensen ◽  
W. Scheer ◽  
S. Thomsen ◽  
T. O. Sonnenborg ◽  
K. Hinsby ◽  
...  
Keyword(s):  
Groundwater Flow ◽  
Sea Level Rise ◽  
Sea Level ◽  
Preferential Flow ◽  
Sea Water ◽  
Saline Water ◽  
Seismic Survey ◽  
Salinity Distribution ◽  
Geological Structures ◽  
The North

Abstract. Geophysical techniques are increasingly being used as tools for characterising the subsurface, and they are generally required to develop subsurface models that properly delineate the distribution of aquifers and aquitards, salt/freshwater interfaces, and geological structures that affect groundwater flow. In a study area covering 730 km2 across the border between Germany and Denmark, a combination of an airborne electromagnetic survey (performed with the SkyTEM system), a high-resolution seismic survey and borehole logging has been used in an integrated mapping of important geological, physical and chemical features of the subsurface. The spacing between flight lines is 200–250 m which gives a total of about 3200 line km. About 38 km of seismic lines have been collected. Faults bordering a graben structure, buried tunnel valleys, glaciotectonic thrust complexes, marine clay units, and sand aquifers are all examples of geological structures mapped by the geophysical data that control groundwater flow and to some extent hydrochemistry. Additionally, the data provide an excellent picture of the salinity distribution in the area and thus provide important information on the salt/freshwater boundary and the chemical status of groundwater. Although the westernmost part of the study area along the North Sea coast is saturated with saline water and the TEM data therefore are strongly influenced by the increased electrical conductivity there, buried valleys and other geological elements are still revealed. The mapped salinity distribution indicates preferential flow paths through and along specific geological structures within the area. The effects of a future sea level rise on the groundwater system and groundwater chemistry are discussed with special emphasis on the importance of knowing the existence, distribution and geometry of the mapped geological elements, and their control on the groundwater salinity distribution is assessed.

V.—On the Cretaceous Fossils found at Moreseat, Aberdeenshire

1898 ◽  
Vol 5 (1) ◽  
pp. 21-32
Author(s):  
A. J. Jukes-Browne ◽  
John Milne
Keyword(s):  
Sea Level ◽  
The South ◽  
The North ◽  
Cretaceous Fossils

Moreseat is in the parish of Cruden, in the east of Aberdeenshire. It lies at an elevation of 300 feet above sea-level, and the surface of the ground slopes to the sea at Cruden Bay, distant five miles to the south. On the north the ground rises gradually, reaching the height of 450 feet above sea in Torhendry Ridge, which is strewn with chalk-flintsingreat abundance.

scholarly journals Ensemble models on palaeoclimate to predict India's groundwater challenge

2013 ◽  
Vol 2 (3) ◽  
Author(s):  
Partha Sarathi Datta
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Humid Climate ◽  
Ensemble Models ◽  
North West ◽  
The Past ◽  
The North ◽  
14C Age

In many parts of the world, freshwater crisis is largely due to increasing water consumption and pollution by rapidly growing population and aspirations for economic development, but, ascribed usually to the climate. However, limited understanding and knowledge gaps in the factors controlling climate and uncertainties in the climate models are unable to assess the probable impacts on water availability in tropical regions. In this context, review of ensemble models on δ18O and δD in rainfall and groundwater, 3H- and 14C- ages of groundwater and 14C- age of lakes sediments helped to reconstruct palaeoclimate and long-term recharge in the North-west India; and predict future groundwater challenge. The annual mean temperature trend indicates both warming/cooling in different parts of India in the past and during 1901–2010. Neither the GCMs (Global Climate Models) nor the observational record indicates any significant change/increase in temperature and rainfall over the last century, and climate change during the last 1200 yrs BP. In much of the North-West region, deep groundwater renewal occurred from past humid climate, and shallow groundwater renewal from limited modern recharge over the past decades. To make water management to be more responsive to climate change, the gaps in the science of climate change need to be bridged.

Oscillations of the Black Sea sea level in the north part of the coast

1999 ◽  
Vol 10 (2) ◽  
pp. 123-130
Author(s):  
Yu. I. Goryachkin ◽  
V. A. Ivanov ◽  
Yu. A. Stepanyants
Keyword(s):  
Sea Level ◽  
Black Sea ◽  
The Black Sea ◽  
The North ◽  
North Part

scholarly journals Interdecadal Baroclinic Sea Level Changes in the North Pacific Based on Historical Ocean Hydrographic Observations

2015 ◽  
Vol 28 (11) ◽  
pp. 4585-4594 ◽  
Author(s):  
Tatsuo Suzuki ◽  
Masayoshi Ishii
Keyword(s):  
Sea Level ◽  
Wind Stress ◽  
North Pacific ◽  
Water Mass ◽  
Mass Density ◽  
Baroclinic Mode ◽  
Sea Level Changes ◽  
The North ◽  
Basin Scale ◽  
The North Pacific

Abstract Using historical ocean hydrographic observations, decadal to multidecadal sea level changes from 1951 to 2007 in the North Pacific were investigated focusing on vertical density structures. Hydrographically, the sea level changes could reflect the following: changes in the depth of the main pycnocline, density gradient changes across the pycnocline, and modification of the water mass density structure within the pycnocline. The first two processes are characterized as the first baroclinic mode. The changes in density stratification across the pycnocline are sufficiently small to maintain the vertical profile of the first baroclinic mode in this analysis period. Therefore, the first mode should represent mainly the dynamical response to the wind stress forcing. Meanwhile, changes in the composite of all modes of order greater than 1 (remaining baroclinic mode) can be attributed to water mass modifications above the pycnocline. The first baroclinic mode is associated with 40–60-yr fluctuations in the subtropical gyre and bidecadal fluctuations of the Kuroshio Extension (KE) in response to basin-scale wind stress changes. In addition to this, the remaining baroclinic mode exhibits strong variability around the recirculation region south of the KE and regions downstream of the KE, accompanied by 40–60-yr and bidecadal fluctuations, respectively. These fluctuations follow spinup/spindown of the subtropical gyre and meridional shifts of the KE shown in the first mode, respectively. A lag correlation analysis suggests that interdecadal sea level changes due to water mass density changes are a secondary consequence of changes in basin-scale wind stress forcing related to the ocean circulation changes associated with the first mode.

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