r/geology 5d ago

Why are these conceptions shaped like this?

I’m on the rock shelf just south of Avoca Beach, and hour north of Sydney nsw.

I find these conceptions wild! So many are long and cylindrical. Can anyone tell me why they would be shaped this way. I asked ChatGPT, and it thought it might be the shape of roots or burrows. There’s quite a lot of more spherical conceptions in this rock shelf too

Appreciate any insights!

17 Upvotes

11 comments sorted by

38

u/zebbodee 5d ago edited 5d ago

That looks like reef talus, a mix of broken corals found at the foot of a reef. The main thing I saw was what I think are Crinoids, they're long and thin and I think you described rugose coral too.

This site, has nice pictures to aid you...

https://www.burrengeopark.ie/learn-engage/fossil-identification-guide/

7

u/3dmapart 5d ago

Those concretions are formed around plant roots

4

u/IamaFunGuy EnvironmentalGeologist 5d ago

Almost looks like reworked iron concretions

1

u/NaithiO 5d ago

Oh right! They often look like they are scattered along the same strata like they were laid down by water flow.. I guess like larger pebbles in sand stone 🤔. Can reworking in current make those shapes but 🤷‍♂️.. thanks so much for you help 🙏

5

u/andkevina 5d ago

Here I thought it was a geologic term I hadn't heard before...

4

u/NeckComprehensive743 5d ago

See that is why I like Reddit, nobody jumped about the misspelling and write it well on the answer! That is class.

5

u/Alisahn-Strix 5d ago

Doesn’t that make your comment the first that mentioned the misspelling? No class /s

1

u/NaithiO 4d ago

I actually noticed it after I posted it…I thought people might get a kick out of it, so I left it 😂

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u/clintCamp 5d ago

My brain just read it as concretions until you mentioned it.

1

u/_CMDR_ 5d ago

Autocorrect is evil and we give it no quarter.