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mikemH

Hi, I'm mike.

I have been reading forum posts for a while now, thought I'd join to share and learn..

I became aware of the local geological features late in life, but now have more time for rock kicking.

The Newcastle coastline has many , easily accessible, points of interest, volcanic dykes, faults, petrified trees, fossils and exposures.

They are in the stratigraphy of the Newcastle Coal Measures, Northern Sydney Basin, late Permian 252-255 Ma.

The majority of preservations are Glossopterids but also horsetails, cordaites and ferns. Maybe not as spectacular as dinosaur bones, but interesting all the same.

I recently picked up a couple of specimens at a local rock platform that might be of interest.

The names and classification are a bit confusing to me, but I've tried to ID them using Mary White's Greening of Gondwana and Australian Fossil Plants, and quote her descriptions.

Please indicate any errors!

 

58d6133e06e18_DSC00637(1280x960).thumb.jpg.7412fb8d2df3f0ab98c85c276d77da4c.jpg

Photo 1 (..637)

Palaeovitiaria, ( glossopterid leaf ), no mid rib, no medium groove and the veins are almost parallel with few cross connections. 

 

58d61353bfcc0_DSC00644(1280x960).thumb.jpg.7f5663dff9f6fcd6669a391379767d1e.jpg

Photo 2 (..644)

On the left, glossopteris leaf, prolific in the area,

On the right, Umbellaphyllites ivinii, a horsetail ( arthrophytes ) with leaf sheath segments completely fused, like a little umbrella.

 

58d6136935734_DSC00641(1024x768).thumb.jpg.6636d0560d664512c986e4e97fba0b23.jpg

 

58d6137490516_DSC00642(1024x768).thumb.jpg.ee2b66a77693cad4db8efae3087f6488.jpg

Photo 3 & 4 (..641 & ..642)

Both sides of a typical fossiliferous rock found adjacent to the coal seams, a compressed mass of various leaves and stems.

This example has been mineralised (grey siderite??) , but has not completely "rusted" thru to form a red/brown limonite ??

 

Regards, mike.

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Fossildude19

Welcome to the Forum, Mike. :) 

Your plant fossils are quite stunning. :wub: 

Looking forward to seeing more. 

Regards,

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Fruitbat

Welcome to The Fossil Forum!  Those plant fossils are really exquisite!

 

-Joe

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Yvie

Welcome.:envy:

looking forward to seeing more

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mikemH

Thanks all.

The photos show up the fossils quite well.

These modern compact cameras are magic, I just leave it on auto.

Cheers,

mike.

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mikemH

Thought a few of the local features may be of interest.

The rock platforms are best accessed at low tide, even then a wary eye should be kept on the swell.

 

591158a655713_ShepardsHill(1)rs.jpg.a4c5e9910671c78720303058ba4d05a2.jpg

 

Shepherds Hill, view from rock platform north of Susan Gilmore Beach. This cliff face has excellent exposures of the Newcastle Coal Measures. The prominent coal seam (upper centre) is the Nobbys seam which is overlain by Nobbys Tuff. Just visible behind vegetation (centre left) is the Dudley seam. Bar Beach formation lies between the two seams and Bogey Hole formation under the Dudley seam.

You can usually find something of interest amongst the boulders and rubble along the base of the cliff.

 

 

DSC00718rs.jpg.97d3df9321577759755a5cca39157d4a.jpg

One such find is this mineralised (grey siderite?) compacted mass of fern like fronds.

 

 

591158b70ee32_PetrifiedTreeMerewetherSouth(5)rs.jpg.88aaadb888409104b553bd343f3bfafc.jpg

A bit further down the coast is Merewether South rock platform where you can find a number of petrified stumps. This one showing highlighted growth rings.

 

 

 

591158dbbde35_DSC00482Dudley1702rs.thumb.jpg.a1fc896147dd5b53bcf0df9d1025bb50.jpg

 

591158ec2cc65_DSC00594Dudley1703rs.jpg.2109f7ac11170b9da9b3e14ead64eddc.jpg

A coupe of km's south is the Dudley rock platform where there is a large exposure of petrified 'forest' (limonite).

The fossilised wood along the Newcastle coast is describe as Glossopteris and Dadoxylon.

 

 

591158ff51c8c_PetrifiedGlossopterisstumpandroots.(chalcedony)(2)rs.jpg.2b67513422791e7803ea1b0ccfc83c95.jpg

Further south again is Swansea Heads. Here there are a number of interesting features. The photo above shows a mineralised (chalcedony?) stump with root system. The fossilised trees in this area are thought to have been felled by a volcanic blast, similar to the Mount St. Helens eruption.

 

A very informative excursion report by Roz Kerr, 2016, Crab Beach and Swansea Heads Excursion, can be found on the Amateur Geological Society of the Hunter Valley web site in GeoLog 2016.

http://agshv.com/pdffiles/Geo-Logs/2016.pdf 

 

Other sources are,

 

Geology of the Newcastle Coastline, N. S. W. Department of Industry, Resources and Energy.

http://www.resourcesandenergy.nsw.gov.au/__data/assets/pdf_file/0005/539204/Geology-Newcastle-Coastline.pdf

 

Brian England, 2016, Bar Beach Geology and ANZAC Walkway, AGSHV GeoLog 2016.

Link as above.

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Fossildude19

Your grey fern looking item is actually an example of shatter cone or cone in cone structures. 

Very cool landscape you have to look through, Mike. :)

Thanks for posting these. 

Regards,

 

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mikemH

Tim, thanks for that, especially the explanation link. Its good to know why and how.

The cone in cone structures description fits with the location, "....occurring within coals....layers within a shale....""

 

The piece that first caught my eye was smaller and weathered, the "fronds" more discrete.

 

DSC00722rs.jpg.820ef5cecf44c59da634536fc55449d2.jpg

 

Given the other "fern like" mineral/crystal growths, its good to keep this in mind.

 

Cheers, Mike

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mikemH

A few more pics.

 

On the channel side of Swansea Heads is Reids Mistake. this is the site of the petrified forest and tuff that brought about the volcanic explosion theory.

It lies in the Boolaroo Sub Group of the Newcastle Coal Measures, late Permian, 253Ma.

 

DSC00730.JPG.a648ad5e75dcd17b36755644ffcf7a1f.JPG

 

I found numerous stumps but only 3 trunks/limbs, 2 of which, close together and parallel, were orientated east west. There was a fair amount of sand covering the shelf.

 

Not having come across any examples of Vertebraria myself, I was keen to see Diana Kemp's stellate markings (AGSHV GeoLog 2014, page 5).

 

DSC00743.JPG.4d2d5229c86de5c7e26319963d28abe3.JPG

 

I located around 20 or so examples in an area of 2-3 square metres, on the outer (eastern) edge of the shelf. they were slightly elevated, but due to the dip of the strata, would lie under the Lower Pilot seam.

 

DSC00745.JPG.e1b26922b04eb73e90d2e1542eaf26ae.JPG

 

Glossopterid Roots, known as Vertibraia......when roots are seen in cross-section.....they can appear as star shaped structures with rootlets radiating out from the central part. (Mary White, 1988)

 

Quite happy with my day so far I thought I'd have a search along the base of the cliff for something to take home.

 

DSC00736.JPG.e7dc716f95f28fc278b3c36a6c5661d8.JPG

 

Came across the above. Vertebraia, the segmented roots of the Glossopterids which look like vertebral columns or backbones, hence the name. (Mary White, 1988)

 

DSC00761.JPG.b1ee57bfa798446003c41917d4fa0dff.JPG

 

Now looking a bit more closely, a bit further along was another.

 

DSC00763.JPG.9f1bc697bbc673e33f16d66e68a6abbe.JPG

 

Then a third.

The boulders appear to have fallen from the tuff bed immediately below the Upper Pilot Seam, toward the top of the cliff.

All too big to take home!

 

DSC00771.JPG.12753a64af04a7957f2656abbeab83c2.JPG

 

Did find a smaller piece, a bit sad and flat when compared to previous, but worthwhile all the same.

 

References;

Mary White, 1988, Australia's Fossil Plants.

Chris Morten and Ron Evans, 2010, Swansea Heads Petrified Forest, AGSHV GeoLog 2010

http://agshv.com/pdffiles/Geo-Logs/2010.pdf

Chris Morten and Brian England, 2014, Pinny Beach and Swansea Heads, AGSHV GeoLog 2014.

http://agshv.com/pdffiles/Geo-Logs/2014.pdf

 

Mike

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