They
are wonderful
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Sand beaches vary
Sand beaches along the Swedish coast can
vary in length from only a few metres to several kilometres. Our interpretation
of a sand beach is a shallow soft bottom, devoid of vegetation. Differences
caused by variations in wave action, tides and the size and composition
of the bottom materials that make up the beach create a vast array of
beach types. These differences, together with water variations (i.e. salinity),
in reality constitute a variety of living environments. Furthermore, the
living conditions can vary greatly, even on the "same" beach.
Waves, bottoms and construction
More or less all sand beaches, independent
of type, have certain common characteristics. All are composed of bottom
material that has been affected and worn by wave action. The waves constantly
change the appearance of the beach. The affect the waves have depend on
their length, height and frequency. As the waves approach the shoreline,
they start colliding and bumping the bottom and therefore slow down. Wave
movements can cause an eddying effect and bottom material is whirled up
and relocated. (In a new window you can see how waves
roll in towards the beach and how sand beaches are built up.)
Sand banks
As the waves slow down they become higher
and steeper and as they approach shallow bottom, they break and surf occurs
in the so called surf zone. In the surf, the speed of the water towards
the shore under the wave peaks is faster than the outgoing under the wave
troughs. This action causes a natural sorting of the sand and gravel and
can build large and mobile formations such as bars, spits and banks.
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