Tag Archives: seabed

Strolling on the sea bed

At high tide on a calm day if you’re standing near the water’s edge you may notice the sea give a little jiggle, an extra ripple or two, as if to say I’ve made it on time. Then it turns and it’s on its way out again: out and out for just over six hours until it reaches the low tide mark. As the shoreline drops away with the outgoing tide the sea becomes shallower and the sea bed is revealed. On exposed ocean beaches the sea bed is sandy and you can walk right down to the low tide mark and paddle. In other parts of the coast fabulous rock pools are revealed as the tide drops: kids of all ages love peering into their depths for crabs and shrimps. Sometimes, on more protected inner harbour beaches squelchy, slippery, slidy mudflats separate the beach from the receding tide and Cockle Bay would probably be one of these … if it weren’t for the cockles.  How many million and trillions of cockle shells are there? Cockle Bay, in east Auckland, is one of my favourite beaches. There are crushed cockle shells all along the shore – some quite large chips higher up the beach, and more finely crushed shells nearer the water’s edge. About an hour after high tide the flat seabed is gradually uncovered and this too is covered with cockle shells so that you can walk all the way out to the low tide mark accompanied by the crackle and crunch of the shells breaking beneath your sandals.

Carolyn Ellerslie2

This photo shows Cockle Bay beach a short while after high tide. The high tide mark is identified by the narrow  line between the lighter and darker bands of beach.

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Cockle shells cover the beach.

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I took these two photos from the same spot on the sea bed at dead low tide – just over 6 hours after high tide – the beach and the water’s edge are a long way off!

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Tiny sea creatures have left their tracks in the sand as the tide receded.

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This massive piece of wood is completely waterlogged so that it can no longer float. It has its own little pool complete with seaweed.


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There’s nothing new about picnicking at Cockle Bay! This is January 1939!