At 02:33 AM 7/4/2006 -0000, you wrote:

>--- In fossilclubgroup@..., "fossilclubnsw"

>Hi Albert

>I for one would like to know more about the Maroota project. Thanks
>Paul M



Hi Paul/Albert,


Below is a recent progress report on Maroota by Tessa Corkill.

Plus I'll fill you in a bit about my current ideas by describing some
broader scope.

I'm interested in the Permian stumpfield horizons (assumed to have been
buried under volcanic ash) of which the well known one is at western side
of Lake Macquarie (and also with good coastal exposures near Swansea Heads).

The Maroota project is one of a set of proposals along the
Hawkesbury-Nepean of small and relatively non-technical nature which, are
also any community involvement interest as could arise, along the
Hawkesbury-Nepean river system.

Consider that imediately downstream of where the Nepean River 'comes out
from the moutains' (called the "Nepean Gorge") it has 'dropped' (deposited)
a large semicircular swathe of gravel and sand at Emu Plains/Castlereagh.
The Emu Plains area obviously cannot be quarried as it was early built
over. The Castlereagh area (Upper Castlereagh river flats) was the scene
of the major gravel companies beginning to co-venture decades ago to buy
out all the Upper Castlereagh farmers and gain freehold over the ground for
a scheme to almost all the sand and gravel of the Castlereagh flats and
capture the greater part of the Sydney sand and 'blue metal' market. The
holes left become the "Penrith Lakes". The scheme covers an area of 2000
hectares. It is the largest sand and gravel quarry anywhere in Australia.
It provides 450+ local jobs and injects over $50 mpa into the local
economy. When mined out (and it maybe will be essentially mined out in as
little as 3-4 years more) I think the land goes to the government as some
sort of 'regional park' arrangement.

Now just south of Penrith the Nepean River emerges through the front of the
Blue Mountains Plateau, or the Lapstone Monocline, trending northeasterly
(towards Windsor and Maroota ... part of the intervening distance towards
Windsor being rich in Tertiary "older" gravel deposits - the Rickabys Creek
Formation).
This trend may be following a common ENE-NE structural trends set (examples
of such further southwest or in the upstream direction include the Kowmung
River, Butchers or Black Hollow Creek, Green Wattle Creek, Lacys Creek and
a section of Wollondilly River downstream of Bonnum Pic).

The old (Tertiary) sediments of the river at Maroota are quite rich in
silicified wood. Where did it come from? On the basis of suspicion that
river development was influenced by the abovemention ENE-NE set of structal
trends, my guess is to the SSW - i.e. in the Wollondilly to Nattai River
area west of Picton. I'd be interested therefore in any records of fossil
wood known thereabouts. Are there any significant horizons of fossil wood,
or more stumpfields maybe, to be found in the coal measures there ... or
anywhere else west or southwest or Sydney? If stumpfields really do owe
their preservation to ashfall then ashfalls can be over a large are.

That's the bigger canvas just from my own personal interests. The Maroota
project itself is to collect/compile all that's known of
heritage/geoheritage significance on the Maroota Sand formation.

One of the early steps will be the organising of an excursion. This is
pending the obtaining of permission from quarries or other landowners at
present.

Maroota is also interesting because a basalt flow directly overlies the
Maroota Sand and will allow by radiometric data the getting of a minimum
age of the river deposits there.

If interested in joining in any of the Maroota project activities please
contact Tessa Corkill. I am also nominated co-investigator on an
application to Environment Trust in quest of a little funding for the
project but Tessa is maintaining the mailing list for it and issuing
progress reports.


Best Regards,




John Byrnes

(Geologist, Sydney, Australia)
http://www.lachlanhunter.deadsetfreestuff.com/JohnByrnes.htm





~~~~ MAROOTA PROJECT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



MAROOTA SANDS HERITAGE UPDATE

Research for the project continues, including fieldwork to examine relevant
material (thanks to helpful residents).

I've been looking at old research work into volcanic intrusions that are
reported to overlie small areas of the Maroota Sands. Dating of these will
give a minimum date for the Sands (i.e. the Sands have to be older than the
volcanic material on top of them  I estimate they will be at least 14
million years old). The underground extent of one of the intrusions of
basalt (often called blue metal) was mapped with a magnetometer by
geophysicist P. Cooney in 1966, in order to estimate its economic
importance. It didnt amount to much (only about 6 metres thick at most)
and Cooney stated it was of doubtful economic significance (Geological
Survey Report 66/190). Nevertheless, pieces found on the surface or
ploughed up during farming have been made use of locally for various
purposes, such as decorative walls.

A second even smaller basalt intrusion is supposed to be present in the
area but so far I have been unable to find a magnetometer report for this,
or any of the actual rock.

One of the reports I have been looking at, by D.S. Thynne (Geological
Survey Report 1977/104), has analyzes of dozens of samples from boreholes
in the Maroota Sands and down along the Hawkesbury. At the time they were
interested in gold and other valuable heavy minerals, but the amounts
present were too minuscule to be economically viable. Interestingly, Thynne
mentions that the Main Roads Department had previously been carrying out
drilling investigations for a possible bridge over the Hawkesbury at
Wisemans Ferry. Well, a lot can happen in thirty years, but nothing further
seems to have happened about that!

If anyone has any information or suggestions for the project, I'm happy to
discuss them at any time.

TESSA CORKILL BA(Hons), MPhil.Sydney, AACAI(Affiliate)
Archaeologist, Australian Museum Associate

"Archaeics", 72 Cairnes Rd
GLENORIE NSW 2157
Phone: 02 9652 1470
email: tessa.corkill@...