Distribution, morphology and structure of sea ice pressure ridges in the Baltic Sea
This is a pioneer work to carry out a detailed study of sea ice pressure ridges in the Baltic Sea. The results are based on field measurements. They include measurements of such as the inside structure of ridges and the orientation of ice blocks
in the ridges sails. The aim of this paper is to serve as a basic information about the structure, morphology and distribution of the pressure ridges in the Baltic Sea. The results are compared with the information about the ridges in the Arctic Seas.
The objectives for this article are to describe the ridge-and-runnel enigma that exists in coastal geomorphology and to explain evidence for episodic ridge-and-runnel occurrence from a California case study. Three hypotheses are discussed : 1) quasi
-stationary ridges and runnels may reflect swash-bar growth by constructive short-period waves, especially on macrotidal coasts| 2) mobile ridges and runnels may be muted expressions of longshore bars and throughs migrating onshore| 3) ridges and runnels may
Formal analysis of ridge and channel patterns in maturely eroded terrain
This paper focuses on the formal description rather than the physical explanation of the ridge and channel patterns in maturely dissected terrain| the object of the description is the connectivity within and between these patterns rather than
their geometry. The A. investigates the topological relations between ridge and channel networks, with particular emphasis on the interdependencies between ridge and channel links and paths, and the drainage areas delineated by them.
The response of the Pacific plate to oceanic island and seamount loads has been used to estimate the distribution of ridge crest and off-ridge volcanism on the plate since the late Jurassic. The most extensive event, forming the Hess rise, Line
Islands ridge, Necker ridge, and Robbie ridge, occurred on the Pacific/Farallon and Pacific/Phoenix ridge crests during the interval 90-120Myr BP (Barremian to Turonian). This event, which extended over a much larger area than comparable volcanism
Fabric, paleomagnetism, and interpretation of pre-Illinoian diamictons and paleosols on Cloudy Ridge and Milk River Ridge, Alberta and Montana
L'orientation des cailloux et leurs caractéristiques sédimentologiques indiquent que les diamictons du pré-Wisconsinien (Drift de Kennedy) provenant du Cloudy Ridge (Alberta) et du Milk River Ridge (Montana) sont d'origine glaciaire plutôt que
colluviale. Les données paléomagnétiques et les comparaisons faites avec des séquences de paléosols et de tills similaires permettent de dater les tills du Cloudy Ridge et du Milk River Ridge.
The shoreface-connected ridges along the central Dutch coast
The present study adresses to the questions how the shoreface-connected ridges along the central part of the Dutch coast were formed and what their behaviour is under the present hydrodynamic conditions. The study is based on field observations
and model computations. The field observations focus on the present hydrodynamic and sediment transport processes, on the resulting morphological and sedimentological response, and on the geologic evolution of the ridges. - (AGD)
Probable paleoperiglacial morphosequences in the northern Blue Ridge
Bloc ; Dépôt de pente ; Etats-Unis ; Géographie de l'Amérique ; Lichénométrie ; Maryland ; Northern Blue Ridge ; Pennsylvania ; Périglaciaire
This paper focuses on deposits and structures with a probable paleoperiglacial origin and their relevance to landscape evolution of the Northern Blue Ridge, Maryland and Pennsylvania. The paper's purpose is threefold : to describe the periglacial
Genesis of an elongated ridge at Jæren, southwest Norway : drumlin or marginal moraine?
This paper presents results of morphological, sedimentological and glaciotectonic analyses of one of these ridges at Obrestad. It is suggested that the ridge has been formed by drumlinization of outwash deposits by a glacier advancing towards
Comparison of morphographic features and internal structures of the coastal ridges off the Belgian coast with similar ridge systems in International Colloquy on the Quaternary and Tertiary geology of the Southern Bight, North Sea. Collected
Kustwallen langs de voormalige Zuiderzee. (Coastal ridges along the former Zuiderzee, The Netherlands)
The environmental setting, geomorphology, sediment properties and genesis of ridges along the shore of the former Zuiderzee are discussed. The ridges are largely generated by surf activity of storm waves perpendicular to the coast, between 1170
Linear till ridges in the southern norvegian-swedish mountains. Evidence for a subglacial origin
The stratigraphy and morphology indicate that the ridges were created by squeezing of till into subglacial voids, at some localities most likely related to subglacial drainage networks. The ridges have no clear relationships to deglaciation
landforms in the area. One possible explanation for the preservation of the ridges is that they were created before the last phase of deglaciation and were preserved under cold-based ice.
Relation between superficial sediment grainsize and morphological features of the coastal ridges off the Belgian coast in Tide-influenced sedimentary environments and facies.
In the coastal ridges area off the coast of Belgium a correlation is found between the grain size distribution of bottom samples and the sea bed morphology. A plot of average grain size of bottom sediments along a transect perpendicular to the coast
is out of phase with bathymetry : the largest average grain size values do not coincide with the ridge crest but are observed on the seaward flank. These observations support the hypothesis of a landward accretion of the coastal ridges. - (Les AA.).
Thermal minima along the axis of the Mid-Atlantic Ridge
Mid-Atlantic Ridge basalts erupted near fracture zones seem to have lower quenching temperatures than along unfractured ridge segments probably because of enhanced cooling by exposing magmas to colder fault planes and more intense seawater
circulation. The cooling effect is more pronounced along segments over hotspots with close ridge displacement fabric and recurrent rift jumping, probably reflecting additional complications, including subaxial magma flow about plumes, or the presence
Debris ridges in New Zealand are routinely assumed to be moraines and used as key Southern Hemisphere paleoclimatic sites without detailed evaluation of ridge origin. Here the AA. assess the origin of a debris ridge adjacent to Dundas Ridge
in the Tararua Range, through measurements of ridge morphology and sedimentary properties. The single ridge morphology precludes a protalus rock glacier origin, while the lack of a broad hillslope scar and debris apron beyond the ridge excludes a landslide origin
. Instead, the AA. interpret the ridge as a pronival (protalus) rampart formed by supranival debris supply–from the ca. 200 m-high southeastern slopes of Dundas Ridge–across a snowbed. Re-distribution of snow by prevailing westerlies from Mt Dundas Ridge
The aim of this review is not to discuss the multiple genetic aspects of beach ridge formation but to document their worldwide distribution and their potential as archives for understanding environmental change such as sea-level variations, sediment
supply and palaeo-storm activity during the postglacial coastal evolution. Beach ridge systems, however, belong to the most promising geo-archives for the study of climate change and sea-level variations over the Holocene, as well as for deciphering event
histories. This paper presents examples of some studies in this field, in relation to a global overview of beach ridge systems and their morphological characteristics.
AMS radiocarbon dating of Lake Michigan beach-ridge and dune development
Strandplains of shore-parallel beach ridges bordering the Great Lakes are valuable for reconstructing histories of climate-related lake-level fluctuations. The resolution and imprecision of radiocarbon chronologies can be improved with AMS C 14
dates of roots and rhizomes of plant species associated with the formation and growth of the sand -dune caps of beach ridges. An AMS radiocarbon chronology of beach-ridge formation in northern Lake Michigan shows that information about variation
in the frequency of ridge formation is important for paleoclimatic interpretation.
Numerous AA. utilized the term beach ridge for active and relict, usually wave-built supratidal and /or intertidal forms. The term was applied also to submerged, landward-shifting, eventually stranded bars. A consistent redefinition of the term
is highly desirable. Beach ridges should include all relict strandplain ridges, whether dominated by wave/swash-built or by eolian lithosomes. All active ridge-like shore features, regardless of dimensions, morphology, and origin are excluded. This paper
vegetation spreading from pre-existing dunes are trimmed back by storm wave erosion, forming a dune cliff capped by spillover sand which becomes a foredune as further aeolian accretion proceeds. A berm is defined as an impersistant wave-built ridge or terrace
on the beach face| a beach ridge is a more persistent wave-built ridge formed at or above high spring tide on a prograding sandy coast| a foredune is a ridge of aeolian sand running parallel to the coastline. (L'A.).