A Blog About Stone Gathering, Tumbling and Polishing, and Rocks and Landscapes, from New Zealand – With Musical Interludes (john.tumblestone@gmail.com)
A Series of five Posts describe my three-week stone collecting trip to the South Island by car, starting with the crossing of Cook Strait on Wednesday 27 May. I reached the bottom of the South Island on Day Six, beginning my return on Day 17. On Day 23, I crossed back over Cook Strait and headed for home (Whanganui). The following is an Index of the five Posts and an indication of their Contents:
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Beach just north of Kekerengu, Kaikoura Coast.
Limestone with trace fossil.
Birdlings Flat.
Birdlings Flat stone.
Stone found on the beach east of Hinds.
South Island Stone Collecting Trip, May/June 2020 – First Five Days – DAY 1: Wellington/Picton to Cheviot, including beach just north of Kekerengu (60 kms north of Kaikoura); DAY 2: Cheviot to Christchurch, including beach visit to Birdlings Flat; DAY 3: Christchurch, beach visit to Birdlings Flat; DAY 4: Christchurch to Oamaru, including visiting beach east of Hinds (100 kms south of Christchurch), on the coast 20 kms north of the Rangitata River mouth;DAY 5: Oamaru to Gore, including visit to beach near Kakanui.
Beach agate found north of the Waianakarua River mouth.
South Island Stone Collecting Trip, May/June 2020 – Days 16 to 18 – DAY 16: Visit to Gemstone Beach; DAY 17: Riverton to Gore, with a visit to Riverton’s Henderson’s Bay beach; DAY 18: Gore to Oamaru, with visits to Hampden beach, the beach north of the Waianakarua River mouth, and Kakanui.
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Patiti Point Beach, Timaru.
Patiti Point stone.
Browns Beach.
Wakanui Beach.
Gore Bay.
Gore Bay stone.
End of South Island Stone Collecting Trip, May/June 2020 – Days 19 to 22 – DAY 19: At Kakanui, visiting beaches; DAY 20: At Kakanui; DAY 21:Oamaru to Christchurch, with visits to Patiti Point Beach (Timaru), Browns Beach (near Temuka), and Wakanui Beach (east of Ashburton); DAY 22: Final day visiting beaches, at Gore Bay and near Kekerengu (Kaikoura coast).
Results of a day’s collection on Birdlings Flat – wet colourful stones.
This group includes some banded agates for which Birdlings Flat is known.
Quartzites in the Birdlings Flat Gemstone and Fossil Museum.
Agates in the Birdlings Flat Gemstone and Fossil Museum.
I recently received an email from Sheila in New Hampshire requesting some tumblestones that she could send to friends. I selected 30 polished stones from three South Island beaches to send to her. In Part One of this series of Posts, I described the ten I sent her from Gemstone Beach while Part Two described the ten from Kakanui. This Post describes the ten from Birdlings Flat.
Birdlings Flat is a small village and beach just south of Banks Peninsula, half-way up the east coast of the South Island (see map below). The Peninsula is of volcanic origin but the Flat is located on the far eastern end of a large gravel spit called Kaitorete Spit.
Birdlings Flat is at the eastern end of Kaitorete Spit which created Lake Ellesmere Te Waihora.
The small settlemt of Birdlings Flat and its beach.
Birdlings Flat beach, looking towards Banks Peninsula.
Kaitorete Spit is about 25 kilometres long, cutting off a large lake from the sea:
Over a period of approximately 5000 years, Waihora/ Lake Ellesmere became first a bay, then an estuary and finally a lake, enclosed by the distinctive Kaitorete Spit, a long, narrow barrier of sand and shingle. The beach barrier, or ‘spit’ as it is known, is broadest and feels least exposed where it connects to the volcanic ‘mainland’ at the edge of Lake Forsyth. It tapers to a tenuous connection in the south where the lake is able to be artificially opened.(From “Banks Peninsula Landscape Study”, 2007, page 194.)
The beach at Birdlings Flat is perhaps the most well-known among stone fossickers in New Zealand. A great range of stones have been brought down to the sea from the Southern Alps by half-a-dozen rivers to the south, including stones from Kakanui (250 kilometres away) and even further south. For millions of years coastal currents have swept the stones north to pile against the basalt cliffs of the Banks Peninsula and to form Kaitorete Spit. In her book “The New Zealand Rockhound”, as long ago as 1981, Natalie Fernandez captures the character of the beach accurately when she wrote:
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)
Three videos on YouTube provide a good idea of the beach, its setting and its stones. The first one is nearly eight minutes of drone footage, showing the Birdlings Flat end of Kaitorete Spit. The second one provides a beach level view, just over one minute long, taken on a sunny day with a number of people enjoying the beach. The third one, 2 ½ minutes in duration, shows a stone fossicker hunting for beach agates.
I have visited Birdlings Flat three or four or more times a year since 2016, looking especially for agates and quartzites and jaspers but finding also a range of other interesting stones. I am sending ten of these stones to New Hampshire, some of them being nice quartzites. Here are the first five:
Ten tumblestones from Birdlings Flat.
Dark grey stone with black veins. Could be quartzite.
Jasper.
Could be a volcanic breccia.
Quartzite.
One of Birdlings Flat’s many gray stones, maybe a silicified mudstone.
The second set of five stones from Birdlings Flat:
Light green quartzite.
Dark green quartzite.
The material at the bottom of this stone is harder than the top, hence the shape.
Gray-white quartzite.
Another gray-white quartzite.
In the Introduction to Josie Iselin’s book of photos, “Beach Stones” (2006), Margaret Carruthers observes:
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. (page 7)
For these 30 stones, the next stop on their journey lies across a great ocean and a great continent.
DELIVERY UP-DATE: I posted the stones on 1 December 2020. Sheila sent me a photo on 23 December (NZ time) showing they had been delivered!(It’s winter there, summer here.)
POSTSCRIPT: Sheila kindly sent me a delightful book on New England’s stone walls – thank you!
TumbleStone 
