The Illawarra Fly Treetop Walk, Knights Hill

Yesterday evening the manager of the Illawarra Fly held a special briefing for members of the National Parks Association. I did not get any photos of the structure itself, as the time and the weather were against me. However, their website has pictures and gives the following introduction:

• The Illawarra Fly is a 500 metre long, 25 metre high elevated tree top walk ascending at a gentle grade and suitable for visitors of all mobilities. Nestled amongst the temperate rainforest of the Southern Highlands the treetop walk takes you along the picturesque Illawarra escarpment and offers inspiring views from Shellharbour to Bass Point, Lake Illawarra and the South Pacific Ocean.

• For the thrill seeker a 45 metre high lookout is ascended via a spiral stairway offering panoramic views, combined with the beauty of the rainforest. View the Blackwoods, Gully Gums and Sassafras from a vantage point generally reserved for our flying friends.

Even in the dull, misty light the views along the Escarpment, towards Wollongong were breathtaking, and on a clear day it would provide an unsurpassed view of the Illawarra Region. You look out over Bass Point, and Shellharbour, Albion Park, Lake Illawarra and Port Kembla (and the Steel Works), and on to Wollongong itself. And of course the jagged skyline provided by the local landmarks of Mt Keira and Mt Kembla.

From the Naturalist's point of view the walk starts in regrowth Cool Temperate Rainforest, with Brown Barrel Eucalypts, with true rainforest plants at the lower level of the canopy. They are all growing on rich red basalt soil. You walk in and start down the slope then go onto the metal pathways, which gently rise over the next band of forest, which is mostly Gully Gums (Eucalyptus smithii,) and Silver-top Ash (E. seiberii), with a rainforest understory, of Blackwoods, Sassafras, Scentless Rosewood and of course, Tree Ferns (of both the Dicksonia and the Cyathea genera), and occasional Cabbage Tree Palms. There are numerous vines visible climbing through the tall trees. This "Gully Gum Forest" forms a narrow strip, just about 100 metres wide, as it sits immediately above the exposed edge of the Illawarra Escarpment. The Escarpment Cliffline is visible from the Illawarra Fly in several places, and of course, it has exposed Sandstone rock faces. So one is reminded that the red soil (on the walks in and out from the Illawarra Fly) indicates that, geologically, this mountain top is a basalt cap overlying the Sandstone structure. It is a "volcanic intrusion".

Here is one of the tall Tree Fern as viewed from above, from one of the metal walkways, some 30 metres off the ground.
From my point of view, it was great to see how this enormous structure has been fitted into the forest with barely a tree dislodged. It was built in pre-fabricated modules, then moved in. The tower was craned into place, a fair effort as it reaches 45 metres high.

And this is a Giant Earthworm, some 50cm long (about 18 inches). It was the largest one I have yet seen. They are recorded to grow even longer. They love this red basalt soil, and the high level of organic matter found on the forest floor in places such as this. This fellow had been disturbed when a trench had been dug, but it was in the process of recovering, and making its way out of the 600mm deep (2 feet) trench.The operators of the Illawarra Fly have a policy of employing local staff, and local suppliers of goods, as far as possible. This is an excellent policy as far as the local Chamber of Commerce is concerned.