Christmas Bells

Christmas Bells
Christmas Bells - Blandfordia nobilis
Showing posts with label Sydney_Basin. Show all posts
Showing posts with label Sydney_Basin. Show all posts

Saturday, June 25, 2011

Corybas (Corysanthes) Orchids at Thirlmere and Jervis Bay

I wish to show you some Orchids I photographed yesterday at Thirlmere Lakes National Park.

Before showing you the Orchids, though, I must show this photo. It is a composite of a snap I took yesterday, and one that a friend of mine, Angela, took of a family picnic at Thirlmere Lakes in early 1993 (dated by the age of the children).
You need to click on the image to enlarge it. The point of comparison is that what once was a stone wall at the lake edge, is now a wall some 75 metres distant from the Lake. There are Wattles and other shrubs, about 5 metres tall, growing in the dry sand where the lake has receded. Its level has dropped approximately 20 metres. This is a national disgrace.

However, the area is still providing good Orchid habitat. These are Corysanthes fimbriata (formerly Corybas). The Corybas group are known generally as "Helmet Orchids" for reasons which will become apparent as you read on.

Funny little things, they resemble grapes dropped on the forest floor. They are about that size too, 

These were in the wettest part of the Thirlmere Lakes NP, close to the Blue Gum Creek section (about as far as one can go, except on foot). Technically, at this point one is in the Nattai National Park, part of the Blue Mountains World Heritage Area. In reality, we are still within the Thirlmere area - but there is a definite habitat change in this "far end" of the park. These Orchids were growing in deep leaf litter, in a wet gully, under tall Eucalypts, with some rainforest trees around as well.
Corysanthes fimbriata - face on.
Corysanthes fimbriata -note speckled hood, and fringe visible
Corysanthes fimbriata - viewed just off to the side

Needless to say, everything about the Corybas tribe of orchids involves lying down on the forest floor, to get any decent sort of shots. Fortunately the forest was dry, and the Leeches were all asleep (as befits their Winter Solstice mode), I would hate to do this in summer.

For comparison, here are some related plants, seen at Jervis Bay the week before.

The two sites are similar in one respect. Both are within Sandstone habitats, with deep grey sandy soil. The Jervis Bay site (for the following flowers) is coastal, south from Nowra, the Thirlmere Lakes site is in the heart of the southern "Sydney Basin", close to the Warragamba catchment (see linked "Location" map at the very end of this post - in the red Blogger footnotes).

You can see the Corybas family resemblance. A rounded leaf, flat on the ground, with a funny little hooded flower on a very short stem. Unlike some Corybas species, the flowers of both today's species are open to the outside world, because they are angled back, leaving easy access for pollinators.

These plants are Corysanthes pruinosa
Corysanthes pruinosa - seen from the rear top view.
Note the silvery grey tops of the flowers. whereas the previous ones were dark red and spotty, and very dark inside the flower. Both are heavily fringed around the outside edge of the flower (lower lip).
Corysanthes pruinosa - my best front on view

Corysanthes pruinosa - looking like little spotted "Marbles" on the ground. 

The trick with these plants is to look for their leaves - on the ground. Find them, and then look closely for the flowers. See one, you might realise there are many around.

Unfortunately, my flash unit ran out of battery power at this point and it was way too far to walk back to the car to get spares. So this is the best I can offer.

You'll get the point, however.

I have called these the "Three Wise Monkey" Orchids.
Three Wise Monkey Orchids - Corybas pruinosa.
Perfect grouping.
Completely natural.

Thursday, October 09, 2008

The future of Water is Black - Black as Coal

The future of water is black - Black as coal.

Longwall Mining under rivers and aquifers is totally unsustainable, and against the best interests of society as we know it.
Humans have not evolved to drink coal – we need water.

What is Longwall Mining?
Longwall Mining is an underground mining technique using a huge rotary cutter (“shearer”), on a rail system, which extracts coal from a seam in continuous “faces” up to 300 metres wide. Each “panel” of removed coal may be as long as 2 kilometres. The height of the “shearer” is adjusted to the coal seam being extracted, but in the Illawarra region it averages approximately 2-3 metres high.

Longwall Mining machine, with "shearer" and rails.
Photo: - Coal Leader

In effect it cuts out an underground “room” as wide as 3 football fields are long, and extending for 2 kilometres in length. That is for each single panel. Panels are normally laid out in series, separated by walls of coal, known as “chain pillars”, which vary in thickness from 20 to 50 metres wide.

As mining progresses, the roof of the excavated area is allowed to collapse into the void (known as a “goaf”) behind where the shearer has been working. A collapse zone is formed above the extracted area. Above the collapse zone is a fractured zone where the permeability is increased to a lesser extent than in the collapse zone. Above this level, the surface strata will crack as a result of bending strains, with the cracks varying in size according to the level of strain, thickness of the overlying rock stratum and frequency of natural joints or planes of weakness the strata (Holla and Barclay 2000). The principal surface impact of underground coal mining is subsidence (lowering of the surface above areas that are mined).

Diagram of Longwall Mining - BHP.

(Click to enlarge - there is a tiny figure of a miner there - for scale).

The following notes have been extracted from the NSW Scientific Committee’s declaration of Longwall Mining as a Key Threatening Process under Schedule 3 of the NSW Threatened Species Conservation Act 1995.

1. Longwall mining occurs in the Northern, Southern and Western Coalfields of NSW. The Northern Coalfields are centred on the Newcastle-Hunter region. The Southern Coalfield lies principally beneath the Woronora, Nepean and Georges River catchments approximately 80-120 km SSW of Sydney. Coalmines in the Western Coalfield occur along the western margin of the Sydney Basin. Virtually all coal mining in the Southern and Western Coalfields is underground mining.

2. Longwall mining involves removing a panel of coal by working a face of up to 300 m in width and up to two km long. Longwall panels are laid side by side with coal pillars, referred to as "chain pillars" separating the adjacent panels. Chain pillars generally vary in width from 20-50 m wide (Holla and Barclay 2000). The roof of the working face is temporarily held up by supports that are repositioned as the mine face advances (Karaman et al. 2001). The roof immediately above the coal seam then collapses into the void (also known as the goaf) and a collapse zone is formed above the extracted area. This zone is highly fractured and permeable and normally extends above the seam to a height of five times the extracted seam thickness (typical extracted seam thickness is approximately 2-3.5 m) (ACARP 2002). Above the collapse zone is a fractured zone where the permeability is increased to a lesser extent than in the collapse zone. The fractured zone extends to a height above the seam of approximately 20 times the seam thickness, though in weaker strata this can be as high as 30 times the seam thickness (ACARP 2002). Above this level, the surface strata will crack as a result of bending strains, with the cracks varying in size according to the level of strain, thickness of the overlying rock stratum and frequency of natural joints or planes of weakness in the strata (Holla and Barclay 2000).

3. The principal surface impact of underground coal mining is subsidence (lowering of the surface above areas that are mined)

Damage to some creek systems in the Hunter Valley has been associated with subsidence due to longwall mining. Affected creeks include Eui Creek, Wambo Creek, Bowmans Creek, Fishery Creek and Black Creek. Damage has occurred as a result of loss of stability, with consequent release of sediment into the downstream environment, loss of stream flow, death of fringing vegetation, and release of iron rich and occasionally highly acidic leachate. In the Southern Coalfields substantial surface cracking has occurred in watercourses within the Upper Nepean, Avon, Cordeaux, Cataract, Bargo, Georges and Woronora catchments, including Flying Fox Creek, Wongawilli Creek, Native Dog Creek and Waratah Rivulet. The usual sequence of events has been subsidence-induced cracking within the streambed, followed by significant dewatering of permanent pools and in some cases complete absence of surface flow.

Subsidence associated with longwall mining has contributed to adverse effects (see below) on upland swamps. These effects have been examined in most detail on the Woronora Plateau (e.g. Young 1982, Gibbins 2003, Sydney Catchment Authority, in lit.), although functionally similar swamps exist in the Blue Mountains and on Newnes Plateau and are likely to be affected by the same processes. These swamps occur in the headwaters of the Woronora River and O'Hares Creek, both major tributaries of the Georges River, as well as major tributaries of the Nepean River, including the Cataract and Cordeaux Rivers. The swamps are exceptionally species rich with up to 70 plant species in 15 m2 (Keith and Myerscough 1993) and are habitats of particular conservation significance for their biota.

Flora and fauna may also be affected by activities associated with longwall mining in addition to the direct impacts of subsidence. These activities include clearing of native vegetation and removal of bush rock for surface facilities such as roads and coal wash emplacement and discharge of mine water into swamps and streams. Weed invasion, erosion and siltation may occur following vegetation clearing or enrichment by mine water.

Source: “Alteration of habitat following subsidence due to longwall mining as a KEY THREATENING PROCESS” NSW Scientific Committee

*** *** *** *** ***
What has happened since this declaration was published in 2005? Business as usual, in the mining industry, that's what.

The Dept of Environment and Climate Change (formerly DEC) has done the right thing (in making this declaration), but it is an appalling indictment of the decision makers in the NSW Government, and particularly the Mining Department and the Department of Planning, that they have allowed, indeed promoted, the use of these disastrous mining techniques under the Rivers which are the catchment for Sydney's water supply.

When the estimated 91% of the Illawarra Catchment has been undermined (estimated at some 20 years), what will Sydney do for water, then?

This map shows coal leases under the Illawarra Catchment 5 dams and rivers (Source: NSW Dept of Planning)

The DECC as a "Toothless Tiger".

Don't get me wrong, I support what they have written. But have they really exercised their full powers under the Threatened Species Act to actually prevent damage being incurred? Or have they just issued a "determination" - and left it at that?


These are just some of the powers available to be exercised by DECC:

Interim Protection Order: Minister for the Environment may make an interim protection order for a period of up to two years over an area of land that has natural, scientific or cultural significance. The Minister may also make an interim protection order on land where the DEC Director-General intends to exercise functions relating to threatened species, critical habitat, or declared critical habitat under the NP&W or TSC Acts.

Stop Work Order: The Director-General of DEC may make a stop work order for a period of 40 days if an action is being, or is about to be carried out that would harm a threatened species, population or ecological community or it’s habitat. These orders can be renewed for 40-day periods as required.


I haven't heard of any such powers being used to stop Longwall Mining by BHP Billiton (or their subsidiaries) or their international mining conglomerate allies, such as Metropolitan (Peabody Pacific Pty Ltd) or Gujarat NRE.

Have you?

Thursday, June 26, 2008

Appin and Douglas Park visit - birds and Orchids

Further to my post of yesterday, about the deplorable state of the Georges River, let me now give you the good news.

There were Honeyeaters galore in the trees in Caroline's backyard. Her house sits atop the cliffs of the Cataract River Gorge. There are many Gum Trees along this top edge of the gorge, and, many other native trees and plants down below, in the gorge itself, of course.

The first birds I noticed were the Yellow-faced Honeyeaters, and Little Wattlebirds, and a family of Superb Fairy Wrens ("Blue Wrens"). We sat on the back deck and had a coffee, and listened to the Striated Pardalotes in the trees (always hard to see, while feeding on Lerps on the Eucalypt leaves.) Eastern Spinebills flipped past us, their noisy wing-beats attracting our attention.

Caroline and I then drove past Appin, and went for a walk to the Georges River. We heard Whipbirds calling in the dense shrubbery, as we approached the river. Once we got there, I noticed some frogs calling (but not many). But it was the birds which I was most conscious of. The Yellow-faces were still around, but there were other Honeyeaters, including the wonderfully bright Yellow-tufted Honeyeater, and the ever-present New Holland Honeyeaters. Those birds love Banksias and Grevilleas, both of which were in flower. I saw a female Golden Whistler, and a Grey Shrike Thrush. Two Black Ducks were swimming fitfully on the river, near some reeds.

The highlight for me was hearing (could I believe my ears?) what I thought sounded like the call of the Peaceful Dove. I have not seen this species in more than 20 years. And when I did, it was in central NSW, near Forbes and Dubbo. Could they be here, on the edge of the Sydney Basin?
Sure enough, after a few minutes of walking along the banks of the Georges River, I saw first one Dove, and then, a pair of them, sitting on a dead shrub across the river.These are lovely birds, with a quiet, non-aggressive nature, and a quiet voice. So much "nicer' than the aggressive New Holland HoneyeatersThis photo is not great, but it is diagnostic. You can just make out the blue eye ring, and the fine markings on the back and neck. Definitely not the introduced Turtle Dove.

As we walked back up to the road, I noticed a grassy glade, which looked promising for Greenhoods. Sure enough, there were many large leaves of a Greenhood in this moist soil. After looking around I found two open flowers of the Blunt Greenhood (Pterostylis curta).

It has a lovely shape from side on. And from the front view you can clearly see the diagnostic twisted labellum (tongue).Back at Caroline's a beautifully marked Pied Butcherbird landed in the tree, while I was on the phone talking to Bernie. I whispered to Caroline that the Butcherbird was here, and straight away she went and got some pieces of bread and put them on the deck railing. Clearly the Butcherbird has got Caroline trained, and it rewarded her by zooming straight in and grabbing a morsel immediately.This snatch and grab movement was so fast I only had a moment to point and shoot. No chance to adjust shutter settings, before the bird was off. But you can see what good plumage it had. Clearly an adult male.

Late in the afternoon, the Noisy Miners had moved in and chased away the other Honeyeaters. But they did not disturb a pair of King Parrots feeding on the Wild Tobacco Plant (Solanum mauritianum).

As a late-afternoon bonus, a family of 8 Yellow-tailed Black Cockatoos flew out of the Gorge, below us, and flew to a neighbouring Pine Tree. The younger members of the group then started their droning noises, while waiting for the adults to feed them. Who would be a parent?

Wednesday, July 05, 2006

The Nature of the Illawarra Coastline

This is Wollongong and the Illawarra coastline, as seen from Mt Keira lookout, above the city. Click on that image to see my panorama of this spectacular coastline - perhaps the most dramatic in Australia.

This fractured coastline is formed by the broken-off edge of the Illawarra Plateau, which is, in effect, a huge sandstone slab which stretches for 40 Kms behind the point of this viewing platform. Indeed it forms part of the huge sandstone formation which includes the Blue Mountains, and the area north of Sydney, nearly as far as Newcastle.

That is the geological formation known as the "Sydney Basin" (see the image of that region - at left - adapted from "Google Earth").


Here is one of the most popular scenic views of the Illawarra coastline, taken from"Bald Hill", at Stanwell Tops. The view is looking south along the edge of the Illawarra Escarpment, towards Wollongong.

You can see the tiny settlements along the Illawarra Coast. Also visible is the new Sea Cliff Bridge which forms part of the Lawrence Hargrave Drive.

The dominant peaks seen in the image above all slope upwards on their eastern edge, reflecting the general tilt of the Illawarra Plateau.

Consequently, the water drainage of the entire Plateau behind Wollongong flows inland from immediately behind these coastal peaks, into the 4 main dams on the Illawarra Plateau (see image at left).

Those coastal clifftop peaks form the boundary of the Sydney Water Catchment.


Stanwell Park is famous for its historical association with Lawrence Hargrave, who developed and tested his revolutionary Box Kite there. So, this place is important in the history of aviation, for Hargrave's design and plans proved to be of great inspiration to the Wright Brothers.

Hargrave's image and his Box Kite were included in the first Australian $20 note, when decimal currency was introduced to this country in 1966.

Sunday, June 11, 2006

The Nature of Kangaroo Valley

Having metaphorically destroyed Kangaroo Valley, yesterday, today I show it in a "different light". Quite literally.

Today, the valley was clear, and yet the shadows from clouds, and the "spotlight' effect of the sun gives a good view of the details of the deeper parts of Kangaroo Valley, and the far distant Shoalhaven River Valley. It even shows the Buddawang Ranges.

The Buddawang Ranges are a small range of hills which poke out above the surrounding Sandstone Plateau, on the south side of the Shoalhaven Valley. They are south of the road which runs from Braidwood to Nowra, through Nerriga and Sassafras. Sassafras is an area of rich basalt soil, similar in nature to Robertson.

One can clearly see the typical sandstone clifflines on the southern boundary of the Shoalhaven Valley.

Much closer to hand lies the ridge which runs from the village of Fitzroy Falls, along towards the Barrengary Mountain, which is the entry into the Kangaroo Valley (along the main road from Moss Vale - to the west). Along that ridge lies a huge "surge tower" which is an integral part of the mini-hydro electrical plant which is found between the Kangaroo Valley and Fitzroy Falls.

This blog entry started out as a "scenic tour" of Kangaroo Valley, however, I ought briefly explain something to do with the "surge tower".
Apart from the energy-generating significance of the Kangaroo Valley hydro scheme, this pipeline has become a vital part of the Sydney Catchment Authority's plans for "drought-proofing" Sydney. Plans have been announced for pumping a far greater amount of water from the Shoalhaven River catchment into the Sydney Basin.

This pipeline is the critical link between the Shoalhaven River and the Sydney Basin water catchment system. It runs from the main dam, on the Shoalhaven, Lake Yarrunga, (a.k.a. Tallawa Dam), via the small, but critical Bendeela Pondage), then water is pumped up the Barrengary Mountain to the Fitzroy Falls reservoir. From there, water is again pumped up, and under the village of Burrawang, and down into the Wingecarribee Reservoir. So less than 20 kilometres of pipes and canals result in linking the huge Shoalhaven River catchment into the Warragamba Dam and Nepean River catchments (via the "Glenquary Cut" from the side of the Wingecarribee Reservoir).

I shall talk more about the diversion of Shoalhaven River water into the Sydney Catchment later.