Beach ridges

2011 ◽  
Keyword(s):  
Beach Ridges

INTERPRETING PALEOHYDROGRAPHIC DATA RECONSTRUCTED FROM STRANDPLAINS OF BEACH RIDGES IN THE LAURENTIAN GREAT LAKES

2017 ◽  
Author(s):  
John W. Johnston ◽  
◽  
Erin P. Argyilan ◽  
Steve J. Baedke ◽  
Sean Morrison ◽  
...  
Keyword(s):  
Great Lakes ◽  
Laurentian Great Lakes ◽  
Beach Ridges

A new Clitocybe from the Alaskan Arctic

1976 ◽  
Vol 54 (9) ◽  
pp. 976-980 ◽  
Author(s):  
Gary A. Laursen ◽  
Orson K. Miller Jr. ◽  
Howard E. Bigelow
Keyword(s):  
New Species ◽  
Beach Ridges ◽  
Microscopic Features ◽  
Alaskan Arctic ◽  
A New Species ◽  
High Center

A new species of Clitocybe is described from the Alaskan Arctic. This agaric grows on low-center polygon rims, high-center polygons, and on beach ridges. Drawings of microscopic features and macrophotographs are included.

Late-Holocene Formation of Lake Michigan Beach Ridges Correlated with a 70-yr Oscillation in Global Climate

1996 ◽  
Vol 45 (3) ◽  
pp. 321-326 ◽  
Author(s):  
Paul A. Delcourt ◽  
William H. Petty ◽  
Hazel R. Delcourt
Keyword(s):  
Late Holocene ◽  
Lake Michigan ◽  
Global Climate ◽  
Temperature Oscillation ◽  
Beach Ridges ◽  
Climate Fluctuations ◽  
The Past ◽  
Fundamental Part ◽  
Atmosphere System ◽  
Centennial Time Scale

AbstractA radiocarbon-dated series of 75 beach ridges, formed at regular intervals averaging 72 yr over the past 5400 yr, provides further support for the existence of a 70-yr oscillation in Northern Hemisphere climate, postulated recently from instrument data representing less than two cycles of this climate oscillation. Results from this study lend support to the interpretation that internal variations in the ocean–atmosphere system are an important factor in climate fluctuations on a decadal–centennial time scale. A temperature oscillation with a period of about 70 yr has been a previously unrecognized but fundamental part of the global climate system since at least the middle Holocene.

The Environmental Relations of Vegetation Pattern on Chenier Beach Ridges on Bathurst Island, Northern Territory

1993 ◽  
Vol 41 (3) ◽  
pp. 275 ◽  
Author(s):  
RJ Fensham
Keyword(s):  
Sea Water ◽  
Acid Soils ◽  
Soil Nutrient ◽  
Vegetation Pattern ◽  
High Concentration ◽  
Radiocarbon Dates ◽  
Beach Ridges ◽  
Nutrient Levels ◽  
Environmental Relations ◽  
Monsoon Rainforest

Radiocarbon dates confirm a chronological sequence for late Holocene beach ridges at Wangiti Beach on Bathurst Island. The vegetation on these beach ridges can be clearly related to topography and distance from the sea. Monsoon rainforest occurs on the fore-dunes where the nutrient levels of the young sediments are relatively high. The mid-dunes support woodland dominated by Melalueca viridiflora and have nutrient-poor acid soils. Vegetation with a high component of monsoon rainforest species occupies the rear dunes, which have a high concentration of seawater macronutrient cations despite their older age than more seaward dunes. The relatively low elevation of the rear dunes supports the suggestion that soil nutrient levels are enriched by sea water or marine sediments during infrequent inundation events such as those during cyclones.

scholarly journals MÉTODOS CLÁSSICOS DE SEDIMENTOLOGIA APLICADOS À IDENTIFICAÇÃO DE DEPÓSITOS COSTEIROS COMO FERRAMENTA AO LICENCIAMENTO AMBIENTAL (CLASSICAL METHODS OF SEDIMENTOLOGY APPLIED TO THE IDENTIFICATION OF COASTAL DEPOSITS AS A TOOL TO THE ENVIRONMENTAL LICENSING)

2019 ◽  
pp. 180-199
Author(s):  
Renata Cardia Rebouças ◽  
Felipe Castro
Keyword(s):  
Coastal Plain ◽  
Sand Dunes ◽  
Environmental Conservation ◽  
Coastal Environments ◽  
Beach Ridges ◽  
Sedimentary Environments ◽  
Natural Range ◽  
Sedimentary Deposit ◽  
Coastal Deposits

RESUMO:A classificação de ambientes costeiros pode ser uma tarefa complexa. O estudo da geomorfologia na identificação de ambientes sedimentares necessita de uma validação. Não raro, feições como cordões litorâneos são confundidas com dunas. O depósito sedimentar em forma de dunas fica melhor caracterizado quando realizados estudos sedimentológicos, nos quais são observados os parâmetros granulométricos e a morfoscopia dos grãos. Neste trabalho estes métodos clássicos de sedimentologia foram aplicados aos sedimentos de testemunhos coletados na planície costeira da localidade de Mosqueiro (SE). A análise granulométrica e morfoscópica mostrou que, apesar de os sedimentos possuírem algumas características peculiares às areias de dunas, como uma granulometria fina, assimetria positiva tendendo para os finos e distribuição leptocúrtica da curva gaussiana, os sedimentos apresentam outras características como a seleção moderada e a superfície predominantemente polida que indicam que estes depósitos não foram formados exclusivamente pelo transporte eólico. O transporte misto, ora pela água, ora pelo vento, aponta para um ambiente de cordões litorâneos. Embora estes depósitos não tenham sido considerados dunas, é importante não construir na faixa de variação natural da praia para se evitar problemas com erosão costeira, bem como garantir a conservação ambiental e a segurança das pessoas e do patrimônio.Palavras-chave: Granulometria; Morfoscopia; Dunas; Cordões Litorâneos. ABSTRACT:The classification of coastal environments could be a complex task. The study of geomorphology in the identification of sedimentary environments requires validation. Often, features like beach ridges are confused with dunes. The sedimentary deposit in the form of dunes is better characterized when sedimentological studies are carried out, in which granulometric parameters and grain morphoscopy are observed. In this work, these classical methods of sedimentology were applied to the sediments of the samples collected in the coastal plain of Mosqueiro (SE). The granulometric and morphoscopic analysis showed that, although the sediments have some characteristics peculiar to the sand dunes, such as fine granulometry, positive asymmetry tending to the fines and leptokurtic distribution of the Gaussian curve, the sediments present other characteristics such as moderate selection and surface that indicate that these deposits were not formed exclusively by the wind transport. The mixed transport, sometimes by the water, or by the wind, points to an environment of coastal strings. Although these deposits have not been considered as dunes, it is important not to build on the natural range of the beach to avoid problems with coastal erosion, as well as to guarantee environmental conservation and the safety of people and property.Keywords: Granulometry; Morphoscopy; Dune; Beach Ridges.

scholarly journals Beach-ridge architecture constrained by beach topography and ground-penetrating radar, Itilleq (Laksebugt), south-west Disko, Greenland – implications for sea-level reconstructions.

2018 ◽  
Vol 66 ◽  
pp. 167-179
Author(s):  
Priscila E. Souza ◽  
Aart Kroon ◽  
Lars Nielsen
Keyword(s):  
Ground Penetrating Radar ◽  
Abrupt Change ◽  
Beach Ridge ◽  
Sediment Grain Size ◽  
Beach Ridges ◽  
Reflection Data ◽  
South West ◽  
Tide Level ◽  
Ground Penetrating ◽  
Reflection Characteristics

Detailed topographic data and high-resolution ground-penetrating radar (GPR) reflection data are presented from the present-day beach and across successive raised beach ridges at Itilleq, south-west Disko, West Greenland. In the western part of the study area, the present low-tide level is well defined by an abrupt change in sediment grain size between the sandy foreshore and the upper shoreface that is characterised by frequently occurring large clasts. The main parts of both fine and large clasts appear to be locally derived. Seaward-dipping reflections form downlap points, which are clearly identified in all beach-ridge GPR profiles. Most of them are located at the boundary between a unit with reflection characteristics representing palaeo-foreshore deposits and a deeper and more complex radar unit characterised by diffractions; the deeper unit is not penetrated to large depths by the GPR signals. Based on observations of the active shoreface regime, large clasts are interpreted to give rise to scattering observed near the top of the deeper radar unit. We regard the downlap points located at this radar boundary as markers of palaeo-low-tide levels. In some places, scattering hyperbolas are more pronounced and frequent than in others, suggesting differences in the occurrence of large boulders.

A lake-level chronology based on feldspar luminescence dating of beach ridges at Tangra Yum Co (Southern Tibet)

2015 ◽  
Vol 83 (3) ◽  
pp. 469-478 ◽  
Author(s):  
Eike F. Rades ◽  
Sumiko Tsukamoto ◽  
Manfred Frechen ◽  
Qiang Xu ◽  
Lin Ding
Keyword(s):  
Tibetan Plateau ◽  
Lake Level ◽  
Environmental Changes ◽  
Luminescence Dating ◽  
Rapid Decline ◽  
The Tibetan Plateau ◽  
Southern Tibet ◽  
Beach Ridges ◽  
Slow Decline ◽  
Fast Decline

Many lakes on the Tibetan Plateau exhibit strandplains with a series of beach ridges extending high above the current lake levels. These beach ridges mark former lake highstands and therefore dating their formation allows the reconstruction of lake-level histories and environmental changes. In this study, we establish a lake-level chronology of Tangra Yum Co (fifth largest lake on the Tibetan Plateau) based on luminescence dating of feldspar from 17 beach-ridge samples. The samples were collected from two strandplains southeast and north of the lake and range in elevation from the current shore to 140 m above the present lake. Using a modified post-infrared IRSL protocol at 170°C we successfully minimised the anomalous fading in the feldspar IRSL signal, and obtained reliable dating results. The luminescence ages indicate three different stages of lake-level decline during the Holocene: (1) a phase of rapid decline (~ 50 m) from ~ 6.4 to ~ 4.5 ka, (2) a period of slow decline between ~ 4.5 and ~ 2.0 ka (~ 20 m), and (3) a fast decline by 70 m between ~ 2 ka and today. Our findings suggest a link between a decrease in monsoonal activity and lake-level decline since the early Holocene.

Geomorphic Expression of Abrupt Climate Change in Southwestern North America at the Glacial Termination

2002 ◽  
Vol 57 (3) ◽  
pp. 371-381 ◽  
Author(s):  
Roger Y. Anderson ◽  
Bruce D. Allen ◽  
Kirsten M. Menking
Keyword(s):  
North America ◽  
North Atlantic ◽  
Climate Changes ◽  
Lake Area ◽  
Lake Surface ◽  
Atlantic Region ◽  
Beach Ridges ◽  
The North ◽  
Lake Floor ◽  
Lake Surface Area

AbstractEolian and subaqueous landforms composed of gypsum sand provide geomorphic evidence for a wet episode at the termination of glacial climate in southwestern North America. Drying of pluvial Lake Estancia, central New Mexico, occurred after ca. 12,000 14C yr B.P. Thereafter, eolian landforms on the old lake floor, constructed of gypsum sand, were overridden by rising lake water, modified by subaqueous processes, and organized into beach ridges along the lake's eastern shore. Preservation of preexisting eolian landforms in the shallow lake suggests abupt changes in lake level and climate. Available radiocarbon ages suggest that the final highstand recorded by beach ridges may have developed during the Younger Dryas (YD) stade. The beach ridges provide information about lake surface area, which was 45% of the lake area reached during the maximum highstands of the late Pleistocene. A similar proportional response has been reported for YD climate changes outside the North Atlantic region.

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