Sand beach

They are wonderful

Wandering sand bars are usually built up of somewhat heavier sand grains that are carried inward. The weaker outgoing currents usually carry the finer and lighter particles out to sea. The longer waves that flow into the shallows break into surf with wave peaks that slowly diminish in height. Under the surf, sand bars form, and with their steep sides, wander in towards the shore. At low tide it is possible to wander on these sand bars.

Swell zone

The waves end their journey in the swell zone and when they arrive on the beach their movement is irregular. Larger and rounder material is deposited in the deeper areas of the swell zone, while smaller and flater particles are deposited in the shallower end of the swell zone. The larger the deposited material is, the steeper the beach. If a beach is composed of large material and only small waves, the wave energy will be too little to level out the beach and create shoals. These beaches often lack a shallow surf zone. Organisms on this type of beach have a difficult time because of the large material that has been deposited, and because the waves usually have their full force, as they have not been slowed down before reaching the swell zone.

Difficult to swim against the current

Powerful waves press in a lot of water onto the shore. This water often runs in a depression between the beach and bar, until it finds a narrow opening in the bar where it runs out with increased speed, a rip current. While swimming, it is possible to get caught in such currents and be swept out to sea. In Swedish waters there is little risk of such an occurrence because the large oceanic waves do not reach the Swedish coast, but if abroad and caught in such a current, it is easy to find calmer water because these currents are usually rather narrow. By swimming parallel with the beach you will soon leave the strong current.

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Waves, bottoms and construction

Sand movement and erosion

Sand bottoms as living environments

The art of digging

Sand beach organisms

Food web

Change and variation

Swedish beach life

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Bo Johannesson | Martin Larsvik | Lars-Ove Loo | Helena Samuelsson