Month: May 2016

“Beach Stones” by Josie Iselin and Margaret Carruthers (2006)

This is a book celebrating the beach stone in its raw form. Josie Iselin is a photographer and installation artist from San Francisco. She has published seven books which focus on those forms in nature that can be found “at hand” and, in particular, at the beach. She explains in the “Artist’s Note” on page 139 of “Beach Stones”, about ten years previously she abandoned her camera and instead started to use her flatbed scanner to gain a different level of detail in her images. All the pictures of stones in this book are scanned. Margaret Carruthers is an Earth Science writer from Baltimore and confesses to having “a vast collection of rocks” (dust jacket). Among her other books is the co-authored”National Audubon Society First Field Guide to Rocks and Minerals” (2005).

“Beach Stones” is a reflective rather than an investigative work. Stones are objects of intrigue and contemplation. The book collects stones from around the world, including a pair from Greymouth in New Zealand. One review expressed disappointment with the book in that there was not enough information of each stone. But that is not its aim. Its aim is more to get the reader to “really look” at the stones, as Josie has done, and to speak of them in a way that arouses curiosity and leads to further personal engagement with beach stones.

 Physically, the book is 18 cm by 18 cm, consisting of 144 pages. Pictures of stones make up just over half of the book, and many of the pages of text contain just a few lines – the images of beach stones are its preoccupation. It is not expensive (Fishpond.com in New Zealand has it for sale at just under NZ$30). Every now and again, I enjoy spending time with a stone or three from its pages.    

 

Second Batch of Stones Taken to Final Stage of Polishing

These stones were picked up from Riverton beaches in February this year (2016). After about five weeks of tumbling, with careful sorting to weed out stones that would not take the polish effectively, this is the result – 58 stones of various sizes, shapes and colours. I thought initially one could be an agate, which would be a rarity from Riverton beaches, but it is much more likely to be quartz.

This one looked like an agate. Held up to the light, it has the characteristics of an agate. But it is more likely a clear quartz.
This stone has schist-like characteristics
Breccia
In the shape of a shoe
Greywacke and quartz
Maybe a quartzite
The stones straight out of the tumbler barrel
All 58 stones

Polishing Agates from Birdlings Flat: Stage One

I found a small number of agates at Birdlings Flat and was given a number more by people I met on the beach. I have now tumbled these for one week in 100-mesh silicon carbide grit (see the bottom of this Post for an explanation of what agate is). The interesting results are as follows: 

Just out of the barrel, mixed in with ceramic shapes for cushioning and filling.
Drying, ready for inspection.
I had found this on Day One at Birdlings Flat, not aware at the time that it was an agate.
Holding it up to the light – agates tend to be translucent. And often banded.
An irregular shape…
…with an inclusion.
Some colour in this small agate…
…with bands becoming apparent when held up to the light.
This one might be called a moss agate, maybe…
A different degree of translucency.
Irregular and banded.
More gnarly.
No apparent banding in this one.

The Gitche Gumee Museum is a rock and mineral museum in in Michigan. Its website has the following explanation about agate and its formation:

“Agate is a form of chalcedony, which is silicon dioxide in the form of microscopic fibrous quartz crystals. Agates naturally develop when an empty pocket inside a host rock, usually volcanic lava,  fills in molecule-by-molecule, layer-by-layer, as these microcrystals form concentric bands or other patterns. The colors and arrangement of the microcrystals are influenced by changes in pressure, temperature, and mineral content that occur during the formation process. The empty cavities and seams filled with fluids rich in dissolved and suspended quartz molecules (silica), as well as other mineral impurities. When the silica concentration became supersaturated, it developed a gelatin-like consistency either throughout the pocket or in a layer that served as the active crystallization front. Over time, the silica molecules began to form miniature fibrous microcrystals that attached to the sides of the cavity or seam. During the filling-in process other mineral impurities collected at the inside of the chalcedony silica band, forming intervening and often contrasting bands.” 

Wikipedia puts it like this:

“Most agates occur as nodules in volcanic rocks or ancient lavas, in former cavities produced by volatiles in the original molten mass, which were then filled, wholly or partially, by siliceous matter deposited in regular layers upon the walls. Agate has also been known to fill veins or cracks in volcanic or altered rock underlain by granitic intrusive masses. Such agates, when cut transversely, exhibit a succession of parallel lines…giving a banded appearance to the section. In the formation of an ordinary agate, it is probable that waters containing silica in solution – derived, perhaps, from the decomposition of some of the silicates in the lava itself – percolated through the rock and deposited a siliceous coating on the interior of the vesicles. Variations in the character of the solution or in the conditions of deposition may cause a corresponding variation in the successive layers, so that bands of chalcedony often alternate with layers of crystalline quartz.” 

Birdlings Flat Stones After First Stage of Polishing

These stones have spent one week in a tumbling barrel with 100-mesh silicon carbide grit. This first stage of the tumble-polish process removes the weathered outer layer of the stone and brings out its colours more clearly. Many of these stones will be quartzites.

Just out of the barrel and having the slurry washed off – plastic pellets also present, used to provide some cushioning to minimise the stones striking one another
Drying before being examined individually to decide what happens next to each stone

 

My Visit to Birdlings Flat, Day 2: Stone Collecting

I bought some stones from Vince Burke at the Gemstones and Fossil Museum. I normally only like to collect what I find but there are special exceptions – and the Museum is a special place. Vince threw in some extras as well, so I came away with two rock agates from the Woolshed Creek area near Mt Somers, three large agate stones from Birdlings Flat, and some petrified and agatised wood from the Hororata River area. 

But my main purpose that day was to find stones of my own that I could polish. So after I had visited the Gemstone and Fossil Museum, I spent about 2 1/2 hours on the beach, concentrating my time on the northern end, walking all the way to the cliffs. The wind was much stronger, but down near the waves was the lowest part of the beach and somewhat sheltered from the north-wester. There were slightly more people around this day than the previous one – mainly fishing and, like me, hunting for stones.

I chatted with three people. Charles came from Christchurch and had been interested in stone collecting for just a couple of months – he had a friend who polished stones but did not himself have a tumbler. Charles was nearing retirement age, like myself. He explained to me that he was mainly looking for agate stones – he gave me some he had found. I had not developed the eye to find them as they are rather plain looking and I tend to seek out colour. As we talked, Charles said, “Oh look, there’s one!” and he stepped a metre away to pick up a small agate. And a minute later, he spotted another one not far away.

Walking eastwards along the beach at Birdlings Flat
A fisherman ahead, and then Charles, who gave me some of the agates he had just found
I reached the cliffs at the end of the beach but did not linger long under them.
That night, I washed and inspected the stones I had collected.
Some of Day Two’s stones.
The agate stones I took away with me, most of them given to me by people I met on the beach.
The Museum stones. At the top is a rock agate from the Woolshed Creek area of Mt Somers; there is another one of these at right centre. At left centre are three large agate stones from Birdlings Flat. At the bottom, closest to the camera, is some petrified wood (left) and some dark agatised wood (right), from the Hororata River area.

Later I ran into a woman who I found out was the daughter of Vince Burke, the Museum man. She was also out looking for agates and generously gave me a handful. Later still, I encountered a local on his afternoon walk who told me a bit about the beach and its dangers. “It’s a killer beach”, he said. The waves can be treacherous, coming in further and more quickly than one anticipates – turn your back on them to your peril. And it gets deep quickly off shore – people who go in after their dog can get into trouble. He also gave me a few agates he had collected that afternoon. 

I reached the cliffs at the north end of the beach but did not linger there. Charles had explained that one of the Christchurch area earthquakes had brought down part of the cliff-face. I had experienced a small but distinctly-felt earth tremor the night before in Christchurch and I was uneasy to focus too long on the stones at my feet when a mass of over-hanging cliff loomed above. 

I collected somewhere between five and six kilograms of stones that day, to add to the eight kilograms from Day One. That evening I packed them carefully into both my cabin baggage and checked baggage for my flight the next day back to Hamilton. Heavy bags!

My Visit to Birdlings Flat, Day 2: Gemstone and Fossil Museum

On my first day at Birdlings, I had seen the sign for the Museum so decided to visit it at the start of Day 2 of my visit. I had seen references to it online, where it was described as a private rock collection open to the viewing public.  One community information site added: “The display is mostly Canterbury material gathered from the rivers and hills, agate, quartzite, jasper, petrified woods etc, of which after many years would have all ended up on the beach at Birdlings Flat.” Another site stated:  “The Gemstone and Fossil Museum was opened in February 2003 by Vince and Colleen Burke and their children, who collected the many kinds of gemstones off Birdlings Flat Beach over 34 years. The collection has grown to include fossils collected since 2002, mostly from Amberley Beach to Kaikoura.” Vince is quoted in a 2012 North & South article on the Little River area as saying, “My wife wanted me to get everything out of the lounge” when they decided to live permanently at Birdlings Flat, sometime after his retirement as a builder in 2003.

The Museum is located at the end of Hillview Road at Birdlings Flat, a narrow road crowded on both sides by holiday homes and residences. Going in the gate, I found myself in a large courtyard to the left of which was the Museum building. A sign said to blow the horn on the wall, so I did, and Vince appeared and opened up. Inside is possibly the best laid-out and presented display of rocks and fossils that I have ever seen, a testament not only to the Burke family’s passion for stones and fossils but also to Vince’s intelligent ordering and labeling of the material being presented.

My favourite corner contained the petrified wood, agates and quartzites.

Petrified wood:

Agate stones:

Quartzite and rhodonite:

Perhaps more than half of the displays are of large colourful agates, most of them found by Vince himself in different parts of Canterbury:

One wall has a display of agates and rocks from different parts of New Zealand. Entry to the Museum is free, though donations are welcome, and you can purchase your own stones, rough or polished, to take away with you:

Vince graciously showed me around and shared some of the stories associated with various stones, especially the large colourful agates. He helped me to identify some of the stones I had been collecting recently. I bought some petrified wood and agate stones on the way out, and Vince then showed me around his workshop which contains his large homemade tumblers, vibratory vats, and cutting saws. All in all, an overwhelming and amazing experience.

Birdlings Flat Gemstone and Fossil Museum is open every day, 9.30 am to 5 pm, except when Vince is away rockhounding.  

See also “Another Visit to Birdlings Flat, Late June 2016 – Part Two: Birdlings Flat Gemstone Museum Again”.

January 2024, Article in Otago Daily Times about Vince’s desire to sell the Museum “Rock collection faces uncertain fate”.

   

My Visit to Birdlings Flat, Day 1 of 2

Last week I visited Birdlings Flat. The weather and tide were very good. Even though it is just about winter, the temperatures were in the mid-20s (centigrade) due to a strong warm north-westerly wind. And the tide was going out, meaning that wet stones were accessible at the tide-line. Some cars were parked partly on the beach but I didn’t want to risk getting stuck in the loose stones so stayed up near the road. The walk to the sea is across about 300-400 metres of stones, mostly greywacke it seems, and sometimes sorted into different sizes by natural processes – a patch of larger stones is followed by a band of smaller stones. There were a couple of people fishing from the beach, a couple sitting and watching the waves, and a photographer tramped the stones near the eastern end. A motor-cyclist went up and down the beach a bit further west, but otherwise it was a very quiet scene.

The parking area at Birdlings Flat
This is the area, near the eastern end of the beach, where most of the stone-hunters spend their time
Looking downwards while crossing towards the tide-line
Looking westwards upon arrival
Getting closer to the east end, where the beach gets steeper towards the surf
The beach is wide and stony
Looking eastwards upon arrival

When I reached the tide-line, I spent about 3 1/2 hours walking initially westwards along the beach before turning back and walking eastwards. I had intended to reach the cliffs at the east end but gave up before I got there as I had collected quite a few stones already, my backpack was getting heavy, and I knew I would be coming back the next day. Late afternoon, before heading back to Christchurch for the evening, I drove down Bayleys Road which runs along Kaitorete Spit. After about 9-10 kilometres, there is a beach access track. I spent about 30-40 minutes on the beach there, scanning for more stones. Here there is more sand and less stones but still some excellent pickings are possible.

Driving down Bayleys Road, along Kaitorere Spit
At the beach access half-way along Kaitorete Spit, looking eastwards towards Banks Peninsula and the Birdlings Flat beach I had just left
Looking westwards – many fewer stones but still well worth a fossicking walk

I ended up with about 8 kilograms of stones.

Some of the stones I collected.
More of the stones I collected.
The most beautiful stone I found, probably quartzite.
I didn’t realise it at the time but this is one of the famous agate stones that can be found at Birdlings Flat. This one is cubic and banded.

See also My Visit to Birdlings Flat, Day 2: Gemstone and Fossil Museum and My Visit to Birdlings Flat, Day 2: Stone Collecting.

Birdlings Flat III: Selection of Online Sources

BEACH FROM THE AIR – YouTube clip, Birdlings Flat and Halswell Quarry – the first 60 seconds of this short clip contains some aerial drone footage of Birdlings Flat, October 2017

LANDSCAPE DESCRIPTION – “Banks Peninsula Landscape Study”, for Christchurch City Council 2007, pages 194 to 197 are on Kaitorete Spit/Birdlings Flat

HISTORY – Wikipedia entry on “Birdling’s Flat”

TV PROGRAMME – Canterbury Television programme “Love Thy Neighbours” (August 1999) about some trouble between neighbours at Birdlings Fat, containing some good footage of the beach and village as well as some interesting historical material about the village (16 minutes 30 seconds long YouTube clip)

RADIO PROGRAMME – Country Life, “Down at the Beach”, 14 August 2014 Radio NZ Programme, interviews with 5 Birdlings Flat residents 

A BEACH RICH IN GEMSTONES – Te Ara, The Online Encyclopedia of New Zealand, brief entry “Looking for Gemstones, Birdlings Flat”

GEOMORPHOLOGICAL DEVELOPMENT – “Significant Coastal Lagoon Systems in the South Island New Zealand” by R.M. Kirk and G.A. Lauder, 2000, Department of Conservation, see pages 18-24 on “Waihora Lake Ellesmere” which also refers to Kaitorete Spit and Birdlings Flat

AGATES – Craig McGregor’s page on “Birdlings Flat Agates” from his website “Craigs Gems”

PHOTOS OF A VISIT – Licorice Allsorts, a blog by New Zealander Angela Hill, excellent set of photos taken on a visit to Birdlings Flat in May 2014

HISTORICAL SCIENTIFIC ARTICLE – “The Lake Ellesmere Spit with Map, Sections and Photographs” by R. Speight, in Transactions and Proceedings of the Royal Society of New Zealand, 1930

MOVIE CLIP OF NORTH END WAVES – YouTube clip, “Birdlings Flat North End Cliffs”, October 2012

ANOTHER MOVIE CLIP OF STORMY WAVES – YouTube clip, “Agate fossicking at Birdlings Flat with Doug”, showing some wild waves, Feb 2014 

PHOTOS OF GEMSTONES – “Gemstones” by Jocelyn Thornton, 1985, see page 33, “Beach pebbles – Birdlings Flat”

STONES – Country Chic Crafts New Zealand, a blog by Janette Ritchie from Springston, Canterbury, post on “New Zealand Gemstones” with a number of photos of Birdlings Flat stones, including agates and petrified wood

PHOTOS AND DESCRIPTION – Adrienne Rewi Online, a blog, post “Back to Birdlings”, November 2009