GC64PN5 Yamba Breakwall (Earthcache) in New South Wales, Australia created by Herbz

GC64PN5 ▼

A cache by Herbz Message this owner

Hidden : 10/7/2015

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Take a stroll along the Yamba Breakwall - A site of both cultural and geological significance.

Yamba owes its special character to the fact that it is situated at the entrance of the largest estuarine system in NSW. When white settlers first arrived they found that their ships, their lives and their prosperity were constantly endangered by the treacherous Dirrangun’s bar and reef at the Clarence River mouth.

Ariel view of Clarence River mouth

To the Aborigines the life giving river was a sacred place and a number of legends relate to its creation in the Dreamtime. Once such legend goes like this;

There was once a mean, crotchety old woman called Dirrangun who held power over the rest of the tribe because she alone knew the source of the sacred spring that supplied their water, which she had dammed up in a secret place. A young man, however, discovered the dam and broke down its stone walls. The water flowed down country towards the sea. Dirrangun was infuriated and threw up mountains like Mount Ogilvie to try and stop it, to no avail. Near the entrance to the sea, in a last desperate attempt, she threw herself across the spring, which had now grown into a big river. The river flowed over her and she turned to stone, creating the reef and bar that now lie at the river mouth.

The Port of Clarence extended from the river entrance at Yamba (initially called Clarence Head) and Iluka, upstream nearly 50km to Grafton. It was suggested that, being navigable for 67 km from the entrance, the Clarence River could be used for greater penetration by ships from the sea than anywhere else in Australia. There had also been continual agitation for construction of a “deep-sea” port”.

The main component of the Port of Clarence is the entrance works, which was constructed in four stages:

Stage 1 – Moriarty’s Scheme (1862-1889)
Stage 2 – Sir John Coode’s Scheme (1893-1903)
Stage 3 – 1914-1917
Stage 4 – Clarence Harbour Works Act (1950-1971)

Moriarty, proposed a scheme to construct short breakwaters and rock training walls on both sides of the river entrance. Construction work on the southern breakwater commenced in 1862, using rock quarried from the adjacent Pilot Hill.

Coode proposed constructing a series of training walls along Goodwood Island and the north bank at Iluka, as well as a half tide training wall, now called, ”The Middle Wall.” The idea was to blast a passage through the reef and construct extending breakwaters projecting to the sea from both heads to create a funnel which would keep the bar scoured by the tidal race. Ironically, before the works were half completed, the Great Flood of 1890 cut the channel through the shoals which to this day is the main channel. Stone for these works was quarried at Angourie. The two popular Green and Blue Pools at Angourie , tapping springs of fresh water, were created as a result of the quarrying.

In 1950, due to the response to continued agitation for a deep-sea port at Iluka, rock was quarried from, and later 40 tonne concrete blocks constructed at, Illarwill Quarry near Maclean and taken down river by barge. While most NSW breakwater works used igneous rock, the material from the Ilarwill Quarry was hard sandstone.

The reef has survived the numerous Acts of Parliament authorising its removal. Bella Laurie of the Jigara tribe at Yamba said;
“The white people asked my father if it would be right if they blew that stone up. My father said, 'No, if they did all the sea would rush in. She's supposed to block it.’ That's the true think that the old people told me....My father told the white people, 'Don't touch that rock.' The white people tried and it rained and rained and wouldn't allow any boat to go to sea. They had to leave that stone and it's still there today.”

Dirrangun’s bar and reef at the entrance to the harbour remains a formidable obstacle to the creation of a deep-water port at Yamba to this day. Time will tell if this will ever become a reality.

Due to its key role in developing European settlements in both the NSW North Coast and Tablelands regions, and its link to the timber export trade, the Port of Clarence is considered to have “State” engineering heritage significance under the historical significance criteria.

As you walk along the rock wall towards GZ, take a moment to ponder the huge investment in time, money and engineering effort that has gone into creating what you see before you today. The landscape has changed significantly over the last 150 years and may well continue to do so in the future.

To claim this Earthcache, walk to the end of the wall and answer the following questions as you go:

Describe the variety of stones and boulders…what types, colours, textures can you see?
Name the 3 locations where stone was quarried to construct the wall.
From the wall, you can see the Yamba lighthouse. What can you see immediately beneath it? What do you think was the purpose of this site?
At the end of the wall path, on the northern side, is a huge block with some very distinctive marks on the vertical face. Describe the marks and how you think they got there.

You can log your find immediately but please send your answers to the CO as soon as you can.

References:

“Yamba Yesterday” by Kieth Howland & Stuart Lee. ISBN: 0 9589691 0 8
www.engineersaustralia.org.au/portal/system/files/engineering-heritage-australia/nomination-title/Port%20of%20Clarence.Nomination.V4.1.July%202012.pdf
Yamba Museum.

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