Abstracts
Abstract
A thin cover of sand and gravel, formed during the early Holocene transgression, covers the northeastern Grand Banks of Newfoundland in water depths of between 70 and 130 m. The sediments are presently being reworked but only during the winter months of higher wave activity. Sediment threshold under waves in 70 m water depth is exceeded over 30% of the time during the months of November to March. Net sediment transport is towards the south-southeast, parallel to the bathymctric contours. Currents required to generate the larger bedforms are known to occur only infrequently. Hence, combined wave and steady flow, often in the same direction, are the probable generating mechanism for the bedforms.
RESUME
Une pellicule de sable et de gravier, formee lors de la transgression du de'but de 1'Holocene, recouvre le nord-cst du Grand BancdeTerre-Ncuveaune bathymctric de 70 a 130 m. Les sediments sontactuellementremanids quoique sculcment durant les mois d'hivcr alors que Paction des vagues est plus intense. Le seuil de prise en charge du sediment par les vagues a une profondeur de 70 m, est d^passe pendant plus de 30% du temps durant les mois allant de novembre a mars. Le transit sldimentaire net s'effectue vers le sud-sud-est, parallelement aux tignes d'isobathym£trie. Les courants requis pour engcndrcr les formes de litage plus imposantes ne surviennent qu'infrequemment. Par consequent, la combinaison des vagues et d'un courant soutenu constitue probablemcnt le m^canisme cngendrant ces formes de litage.
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