Geologija / Geology
 ISSN 1392-110X ISSN 2029-056X (online) |
2006 m. Nr. 4 Peculiarities of sand sorting on the Lithuanian coast of the Baltic Sea
Sand in the coastal zone is subject to a constant interchange between the nearshore and the coast. This process of sand dislocation involves mechanical sand sorting. The research was conducted in the coastal zone of the Lithuanian part of the Curonian Spit. For analysis, eight lithodynamic research profiles were selected. The profiles covered the coastal area from the top of the dune ridge to a depth of 15 meters in the nearshore isobath. To analyze the change of the granulometric composition of sand, four sand fractions were chosen: 0.1–0.16; 0.16–0.2; 0.2–0.315 and 0.315–0.4 mm. These fractions form the basic part of the granulometric composition in the coastal zone of the Curonian Spit. A thorough analysis of the transportation of different fractions across the coastal zone, has shown that the distribution of sand is quite regular. It matches the balance of the active factors that influence sand sorting and the coastal zone relief. The very finest fraction (0.1–0.16 mm) is carried beyond the limits of the sand ridge and deposited at greater depths (7–15 m). Larger particles accumulate closer to the coast, i. e. the 0.16–0.2 mm fraction clusters in the offshore sand ridge zone, 0.2–0.315 mm concentrates in the inshore sand ridge and in the dune ridge, and 0.315–0.4 mm is most abundant on the beach, in the influence zone of the swash.
The general distribution of sand particles shows distinct trends along the Curonian Spit coastal zone. Apart from the effect of waves, sand sorting is also influenced by the transportation directed towards the north. These changes are most obvious on the coast and less evident in the zone of the sand bars. Beyond the limits of the surf, the granulometric composition of sand remains basically unaffected. Keywords: coast, nearshore, sand sorting, grain size, Lithuania, the Curonian Spit, South-Eastern Baltic |
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