Lake Cathie Beach 'rock' formations?

[juju]

Hey there anyone, I was down at Lake Cathie (NSW north coast) on the weekend and across the road (just north of the bowlo) is a short beach access that leads to a seemingly rocky formation nestled between the water and sharply eroded dune cliff.
It looks like rock but on close inspection it seems to be either sand compacted with black or dark brown clay. It's soft enough to carve a finger into.
The stuff had eroded with successive wave action to make some beautiful tunnels and cliffs. These are about a metre in height but one can imagine them being huge caves and coves...
does anyone know what the stuff is?

[WarrenH]

juju, I don't know Lake Cathie, but I'm guessing it is the rock commonly found on the NSW North Coast known as 'Coffee Rock'. It is hardened sands and clays, that were river sediments. Although the word hardened doesn't seem appropriate for Coffee Rock. Geologists use the word indurated rather than hardened. It gets the name Coffee Rock because it looks like compressed coffee grounds. The Coffee Rock at Yuraygir is a very dark brown firm and spongy material, just like the texture of ground up, compressed rubber, floor mats.

On the East Coast, Coffee Rock is found as far north as Fraser Island, I think.

Your photos are very good. This stuff isn't easy to photograph well, it absorbs light rather than reflects it. Top shots, great formations.

Warren.

[juju]

Thanks Warren for a great reply. Yes it is like coffee just a bit more sticky. Amazing how all the clays are dumped together like that over however long a time. I'm full of questions about it and looking forward to going back. The forms really inspire the imagination. I can see pirates in the cove...

[juju]

Here's one of my pics of a half metre high cave with a man added...

[juju]

some more little walkers...

[phan_TOM]

Yep, I'd agree with Warren and say its definitely coffee rock juju, that stuff's pretty common up and down the coast, I really love the shapes it makes
as it breaks down they are very sculptural. We get lots of it appearing from under the dunes and the beaches after storms cause erosion up here. I think
Lake Cathie is actually on the Mid North Coast too (just to be pedantic threw me 'cos I live on the North Coast, horrible place ).

Your photos make me wish I was camping on the coast right now... leprechauns and all!

[juju]

Yes 'tis the mid-north coast.

I think Lake Cathie is actually on the Mid North Coast too (just to be pedantic threw me 'cos I live on the North Coast, horrible place ).

I dunno, there's some nice spots down there. It has changed a lot - used to holiday at Pearl Beach in the 70's as a teenager and remember walking around the rocks from Umina in the dark, after the pub, a little wobbly having spent all my $2 on beer...

[flatfoot]

Interesting. Is that north or south of the Lake Cathie township?

I lived in Port Macquarie in the 80's and was there for a school reunion last year. I killed some time before the reunion by walking down the beach from the surf club @ Lighthouse Beach. I only got about 6km down the beach and didn't see anything as large as what you've shown here. I do remember seeing that type of rock further up the beach.

[juju]

didn't see anything as large as what you've shown here.

lol the last two shots I have retouched in Gimp, adding a human element after my imagination got the better of me (as I said in the first post). If you look closely you'll see the people in these pics aren't quite right...I could probably just manage to wash my feet in the 'lake' and crawl through the 'cave entrance' that is no higher than my thigh.

[flatfoot]

[Capt DropBear]

Interesting. Is that north or south of the Lake Cathie township?

I lived in Port Macquarie in the 80's and was there for a school reunion last year. I killed some time before the reunion by walking down the beach from the surf club @ Lighthouse Beach. I only got about 6km down the beach and didn't see anything as large as what you've shown here. I do remember seeing that type of rock further up the beach.

Off topic: Not the Port Macquarie High Class of 2000 reunion?

[kjbeath]

One characteristic is the high iron content which gives the red brown colour and cements the sand together. there is an excellent example at Rainbow Beach in Queensland, which the 4wd are forced to go around or else go some distance back down the beach and take an inland track. Results in many wrecked 4wd.

rainbowbeach800x600.jpg (134.36 KiB) Viewed 9459 times

[flatfoot]

Interesting. Is that north or south of the Lake Cathie township?

I lived in Port Macquarie in the 80's and was there for a school reunion last year. I killed some time before the reunion by walking down the beach from the surf club @ Lighthouse Beach. I only got about 6km down the beach and didn't see anything as large as what you've shown here. I do remember seeing that type of rock further up the beach.

Off topic: Not the Port Macquarie High Class of 2000 reunion?

A "little" older than that , although I went to Westport.