May 2016 – Page 2 – TumbleStone

Birdlings Flat I: What the Books say

Birdlings Flat is a beach about an hour’s drive from Christchurch in the South Island of New Zealand.

004 — Display in Birdlings Flat Gemstone and Fossil Museum

Lyn and Ray Cooper (1966), New Zealand Gemstones, Chapter 2 “Where to Find the Stones”: Birdlings Flat in Canterbury was, at one time, an excellent source for agates, but supplies are now much harder to find there, mainly because of the area’s close proximity to a large city and the swarms of collectors who have combed it over the past year or so. Good agates can still be found there, but the best time is immediately after a storm, when the sea has turned the surface stones over. (page 28)

Mrs A. Niethe, “Gemstone Localities: New Zealand” in Bill Myatt (ed.) (1972), Australian and New Zealand Gemstones: How and Where to Find Them: Birdling’s Flat (it is named after the late Mr Birdling, who had a farm there) is part of the shingle spit, some 15 miles long, enclosing Lake Ellesmere. Half-a-dozen rivers along the coast to the west carry these gemstones from the hills inland to the sea. For millions of years the set of the current has swept the gravels north to pile against the basalt cliffs of the Banks Peninsula… This is the Mecca of New Zealand’s rockhounds, famed for a variety of gemstones that reads like a geological dictionary. Coloured quartz of many types is the most common – jasper; chalcedony, mostly clear or grey or white, sard, sardonyx. petrified wood of various colours – a lot are fractured, after a while you only keep the perfect ones… Stones reached this beach from many parts of the South Island, presumably through glacial action in the ice ages. Rhodonite has been found here, quartzite, jasper from the Livingstone Mountains to the south-west; prase and plasma from the Hinds River, 60 miles away to the west, and true jade as Maori artefacts. Beware, this beach is extremely dangerous. Turning one’s back on the sea to pick over the rising bank of pebbles is almost involuntary, but it is very risky at Birdling’s Flat where the big waves knock you off your feet. (page 436)

Natalie Fernandez (1981), The New Zealand Rockhound, Chapter 5 “Locations”: Hundreds of rockhounds have cut their teeth on Birdlings Beach – just a short run from Christchurch. Here great rollers break on the stony shore throwing forward stones with a roar as the waves thunder up the steeply shelving beach and sucking them back with a clatter as the waves recede. You can look for your agates and jaspers well back from the water-line but they do not show up clearly unless you dig down, for only the surface layer is dry. More exciting is to hunt along the water’s edge. As a wave slides back an agate is spotted. You leap for it but miss as the next wave roars in, driving you back. You never see that agate again. The beach is steep and the undertow strong. The breakers are especially powerful in a southerly and on the in-coming tide. Few can play this game and keep dry. (page 14)

Fernandez Birdlings Flat — “Birdlings Beach” following page 16, Fernandez, *The New Zealand Rockhound*

Natalie Fernandez (1981), The New Zealand Rockhound, Chapter 5 “Locations”: Birdlings Flat is 26 miles from Christchurch on the Akaroa Road. Shingle beach for 15 miles. There are still some pickings especially with a N.W. wind and an incoming tide. During a Southerly with rough seas the stones are sucked away again. A slight easterly with calm weather builds up the beach again. There is a strong under-current. The great rivers flowing into the Canterbury Bight bring material from inland to the sea. The current brings them north to be deposited where Banks Peninsula forms a barrier. Petrified wood, jasper, grey clear chalcedony, sardonyx, agate. In 1965 the beach was gazetted as a reserve. It is dangerous. (page 114)

Other TumbleStone Posts on Birdlings Flat:

Birdlings Flat II: Location Map and Satellite View (May 2016)
Birdlings Flat III: Selection of Online Sources (May 2016; up-dated 2019)
My Visit to Birdlings Flat, Day 1 of 2 (May 2016)
My Visit to Birdlings Flat, Day 2: Gemstone and Fossil Museum (May 2016)
My Visit to Birdlings Flat, Day 2: Stone Collecting (May 2016)
Birdlings Flat Stones After First Stage of Polishing (May 2016)
Polishing Agates from Birdlings Flat: Stage One (May 2016)
Another Visit to Birdlings Flat, Late June 2016 – Part One: Taumutu
Another Visit to Birdlings Flat, Late June 2016 – Part Two: Birdlings Flat Gemstone Museum Again
Another Visit to Birdlings Flat, Late June 2016 – Part Three: Seven Types of Stones Collected
TumbleStone Calendar 2019 – February, March, April and May

Stones in the Process of Tumbling

These stones have undergone the first stage of tumbling with 100 grade silicon carbide grit. Most of them are from Riverton beaches, in Southland, but a couple are from the West Coast of the South Island (New Zealand). Some will need more tumbling in this coarse grit because they still have small pits or scratches not yet smoothed away.

“The Pebbles on the Beach” by Clarence Ellis (1954/1965)

This book was first published in 1954 (this paperback edition appeared in 1965) but in many ways it is the best book I have so far encountered on the topic of beach stones. It is 20 cm by 13 cm and has 163 pages. Published by Faber and Faber of London, it deals with beach pebbles in the UK but most of its content is relevant to many other localities. This is particularly so of the first four chapters about the beach processes that shape pebbles and the different kinds of pebbles.

There are four colour plates of stones with accompanying interpretive diagrams labeling and describing each stone. Many of these stones can be found in New Zealand too.

I bought this book for NZ$26 (including postage) through Amazon, and it came from Langdon e-traders, a UK charity business established in 2014 to employ and support young men and women with disabilities.

The Sound of Stones Tumbling on the Beach

“…The chatter of the pebbles as they tumble against one another… A beach is a strip of loose material at the water’s edge, a collection of sand and stones assembled, disassembled, and reassembled by the sea. On the geologic time scale, it is ephemeral. And for most stones, the beach is just the latest stop on a journey that began eons ago.” [Margaret Carruthers, “Beach Stones” (with photos by Josie Iselin), 2006, page 7]

I took some video clips during my recent visit looking for stones on Otago and Southland beaches. This movie (below) shows two of the stony Southland beaches on which I spent some time. The first one is the “Back Beach” as I know it, but it is also known more officially as Howells Point Beach, at Riverton. This beach is 90% stony and lies straight across Foveaux Strait from Stewart Island – usually a wild beach with powerful surf, the day I was there it was very calm (though the day was wet, cool and gray). The second beach featured on this movie is Tihaka Beach on Colac Bay, at the far eastern end of the Bay. This is a long stony beach, and the surf was a little stronger than at the Back Beach. So it was particularly at Tihaka Beach that you could hear the stones being tumbled as the waves came in and then receded. Stone tumblers mimic this action and intensify it.