Not Washed Away, On the Highest Tide – Watts Up With That?

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From Jennifer Marohasy’s Blog

January 5, 2022 By jennifer 

It has been an exciting start to the year where I live, because the highest astronomical tide was forecast for 3rd January and there was a cyclone tracking towards us.

On the highest tide each year, I wonder if the waves will reach to the wave cut notch at the bottom of the cliff face, below Boiling Pot Lookout in Noosa National Park that is about halfway down the east coast of Australia, just near where I live.

I have been going around and standing there on the lower platform (Platform 1) for some years at the time of the highest tide.   These tides are in summer in the Southern Hemisphere because that is when the Sun is closest to the Earth, and they usually correspond with a New Moon or Full Moon.

Jen and friends towards the top of Platform 1 waiting for the highest tide for the year in 2020. It didn’t reach as far as us, we weren’t washed away.

This year, on the day of the forecast highest astronomical tide (Monday 3rd January 2022), Noosa was mentioned on the front page of the national newspaper – the story was about the huge swells: up to 4 metres high from ex-cyclone Seth lingering just offshore.

Was this the year I was going to be washed from the wavecut platform at the bottom of the cliff face on the highest tide?

The sea begins at the land’s edge.  Where the sea begins is the sea level – and there is concern that sea levels are rising.

But this platform must be a relic from a time of higher sea levels because even this year with a low pressure system off-shore that raised sea levels, and with the La Nina that further raised sea levels, sea-level didn’t reach the wave cut notch.

These platforms form just below sea level, in the intertidal zone, where the cutting action of waves will bring down great lumps of rock from above.  The debris is removed by the wash, beyond the intertidal zone; the headland recedes landward; the sea eats into the cliff-face; and so, cliffs are formed, with wave-cut platforms at their base.

This platform below Boiling Point Lookout, that I have stood on in past years: it is so wide.

When was it formed? How long were sea levels at that height – how long does it take to erode a cliff face to that width?

This year the waves, on the biggest swells, at the time of the high tide, they hit the cliff face!

Not the sea level, but the swells.

And yet I wasn’t washed away.  Because I wasn’t on the platform!

But my friend Jared was there, and he was not washed away.  You can see him in the drone footage that I have taken – so much footage that now needs editing – that shows the largest swells including as they hit the cliff face the day before (2nd January) with Cyclone Seth just offshore, and the next day (3rd January) which was highest tide day for the year.

Can you see him, my friend, Jared? In a white tee shirt, waiting for the highest tide below Boiling Pot Lookout with the big swells from ex-tropical cyclone Seth.   You can see him and the waves smashing in the footage that I hope to make into a little film.  To know when the short film is released consider subscribing for my monthly e-newsletters.

I was flying my drone (the wonderful Skido) from a ledge beyond the platform into the winds and out to sea so I could get the feature image looking back at the cliff face at the time of the highest astronomical tide, as shown in the feature image at the top of this blog post.

This year I dared not venture below the cliff face at the time of the highest tide, but Jared did – and he was not washed away.   You will see him in the short film that I hope to make about this cliff face and climate change.  To be sure to know when it is uploaded to the internet or ready for showing in the wonderful local Pomona Theatre subscribe for my monthly e-newsletters.

A photograph of Platform 1, taken by Bruce with his phone, just before the highest tide on 3rd January 2022. He also braved the conditions and saw it all with his own eyes.



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