Black Nor'Easter reshapes landscape
There's a cliff scramble down to one of the local waves around Manly. Last week was the first time I've done the trek since the Black Nor'Easter swell and the experience was staggering.
Imagine the layout of your home, you know every corner and doorway and can generally traverse it in total darkness.
Now imagine waking up one morning and it was totally changed, flipped on its side and hardly recognisable. A totally different layout.
This was the scene I came across towards the bottom third of the scramble with familiar rocks that made up the path pushed over or not there at all.
It was like a foreign landscape in the same place, and upon having to mark out a new route across the rocks the scene became even more mind boggling. A rock about as big as a car and five metres above the high tide line had been totally turned on its side and was unrecognisable.
Up to this point I'd wondered how the boulders and ledges below the ocean surface had possibly changed but I didn't give thought to what might happen in the intertidal zone.
The forces needed to move this rock, which would have to weigh three-to-four tons, are hard to comprehend. But then I bring myself to the sight I saw that Sunday when the storm was in full flight and the ocean so angry and beyond anything I've ever seen, even in the Southern Ocean.
The wave I surfed seemed to have the same characteristics as before the large swell but I was cautious to keep an eye out for any misplaced boulders popping up on the already shallow ledge.
Further to this experience was pure evidence of a change in the coastal landscape around North Head earlier this week.
Hiking down to a lesser known area, another three-to-four ton boulder that sits in a large shallow rockpool had been visibly shifted and turned up slightly, with the white underbelly that's usually submerged by water now revealed. It was sticking a foot or two in the air. The rocks surrounding it had all been flipped over as well.
Clearly the waves needed to move such large volumes of rock aren't common, noted by the fact the rock scramble to the selected wave hasn't changed in the eight years I lived in the area, even under the biggest of swells.
Longtime Cronulla local Steven Feinbier came across a similar scene shortly after the Black Nor'Easter event with multiple new boulders scattered across the rock shelf at Windy Point (South Cronulla).
Meanwhile, Aaron Hughes lost fins when coming in at his usual place after a surf at Sandon Point. The channel he ordinarily used had a large rock deposited across it.
Such was the rare and destructive nature of the Black Nor'Easter its scars will be seen for decades to come.
If you've got images or stories of similar changes in your coastal region, post them in the comments below. //CRAIG BROKENSHA
Fresh boulders thrown onto the rockshelf at Windy Point, Cronulla
Comments
Seeing how the recent event shifted and moved some significant rock features around, it's very plausible that Big Rock at Bondi was placed there in a storm back in 1912..
The Big Rock
Pretty crazy stuff
They say the boulders on the bottom at Waimea dance around on big days!
One time surfing Granites on a building cyclone swell I could hear this thunder like rumble but the skies were totally clear.
It was the huge granite boulders rumbling and moving with each set, and the experience was almost spiritual. To hear such a deep rumble from the Earth was unique.
Often hear rocks cracking and clicking at other breaks around the country/world.
A favourite reef/ point of mine is regularly inundated with large swells at reasonably long periods and large boulders are shifted quite frequently.
For a single season there was a large flat slab deposited in the middle of an already shallow section of the wave . This slab was referred to as the pool table due to its size and shape and added an extra hollow section with additional consequences if you failed to negotiate it.....I was actually relieved to discover its absence a few months later.
At the same break there is a large round Boulder - chest high - that disappears and reappears over the years. At one time it was on top of the the shelf 4 metres above sea level , after a bit of time rolling around in the water.
Haha, this is what I was wondering at some of the breaks around here!
Surge at Bower is still there and solid.
That's amazing Craig.
Must of been some storm you guys got up there. Crazy stuff
North head this morning from Maritime BSO..
https://www.facebook.com/nswmaritime/posts/10154257294780631
Wow, that's a lot of rock and super recent, thanks for the heads up Two-dogs!
Open to a south swell and offshore in a nor-easter. Check it!
I think that the triangular rock at North Head was not moved but fell on one corner which caused the other end to protrude upwards, the fall being steep on the South side therefore moving high on the North side (the fulcrum being quite low]. I swam there recently and believe it was moved via erosion not sheer force.
As for the big rock at Bondi, was that a part of the cliff above that has fallen? At Point Nor East on the South coast there are 8 or 10 boulders that clearly come from a missing piece of the cliff above, like a jigsaw. Just around from Quarantine at North Head too, there are a few classic cases of this.
Are the Windy Point boulders these too? Just smaller and less clear?! Eroded over the years by the wind and pedestrians on the shallow cliff then falling with the sudden large-scale erosive forces of the storm surge and high seas from an unusual direction. Then slowly sliding down the rock platform during the high seas.
I don't think waves have the "grip" to lift boulders, only erode around them.
Not sure how that triangle rock initially got there, but it has definitely shifted upwards post the storm event.
I pointed this out by adding arrows pointing to those grooves/cracks in the rock seen near rockpool level before, then up a foot or so post event.
The white clear line indicates the rock was shifted upwards on the side I'm taking the photo of, and downwards on the other side.
I've contacted Steven, but those rocks at Windy Point if I remember correctly where a mix of ones thrown up from the ocean with barnacles on them, and rocks that had sheered off the platform.
Also Marti Paradisis had this to say regarding the changes seen around Tassie: Major changes on our east coast too... However it's pretty amazing how the shipstern landscape changes. At least once a year the rocks in front of the change spot move around!!
If you have a quick walk around the Deadies and Winki rock ledges you'll see a totally different landscape, all shifted by the storm. The ocean has a lot more energy than you think.
Steven just sent this through..
This one has barnacles on top and cunjevoi under it. It was the biggest one of the lot. Several tonnes.
Wow. If that rock really did move UP the shelf then I am very impressed and wrong. I don't understand the physics of waters' ability to pick rocks up (any physics genii out there keen to teach?) but intuitively don't feel that rocks can be moved up that way by waves. The evidence shows otherwise.
I will go to the Nulla next opportunity, I'm fascinated and would love to see those rocks for myself.
I don't understand how a wave could lift a huge boulder, but there is a large amount of evidence to suggest it does. The Bondi Boulder, which is freaking huge, was corroborated by multiple locals that it wasn't there the day before, and was the day after. I have no reason to believe that the report of the 1912 storm were wrong.
Some serious shit goes down under the water.
Studies have shown that big storm waves can substantially move massive rocks. Particularly near cliffs where there is backflow hitting the incoming waves and...KaBOOM!
...
The Queensy wormhole has a new resident..
A few drone images of the North Head rockfall. So nuts.
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