24-458: Lake Grassmere / Kapara Te Hau is a New Zealand waituna-type lagoon in the northeastern South Island , close to Cook Strait . The lake is used for the production of salt. Lake Grassmere, 25 miles (40 km) south of Blenheim and 6 miles (10 km) south of the mouth of the Awatere River , is a shallow lagoon protected from the open sea by a single barrier beach covered by sand dunes. It
48-431: A hapau at its mouth. Over geological time, a spit grew, drift-aligned to the current. It was, initially, as to be expected, wide the southern end where it receives the most sand and gravel, and narrow at the northern end. However, as it grew, it bumped into Banks Peninsula . This stopped it growing, but the sediment kept coming, so it no longer fits the rules of a spit. It's now wider at the proximal end and narrower at
72-434: A long time, and shallow – typically less than 3 metres (9.8 ft) deep. They are tideless and the water is not well mixed by wind. The barrier prevents flushing by rainfall events. All this is evident in the green colour of water in above photo. Te Waihora / Lake Ellesmere is an outstanding natural feature. It is a wetland of international importance and an area of immense cultural significance to Ngāi Tahu . The waituna
96-464: A record at the time. By 1970 the harvest had increased to almost 52,000 tonnes, but this could not match demand, which had grown with industrial development (especially from freezing works and pulp and paper mills). It became evident that Grassmere could not meet New Zealand's salt requirements. Bulk shipments of salt from the Caribbean and Australia were landed at Mt Maunganui, where a vacuum salt plant
120-804: A result of the Ngāi Tahu Claims Settlement Act 1998 . Waituna A waituna is a freshwater coastal lagoon on a mixed sand and gravel (MSG) beach, formed where a braided river meets a coastline affected by longshore drift . This type of waterbody is neither a true lake, lagoon nor estuary. This classification differentiates it from hapua , a type of river mouth lagoon. Both waituna and hapua are rare globally but common in New Zealand , where they are considered ecologically significant as sites of traditional Māori food-gathering as well as for their diversity of fish and bird species. Waituna form an interlinked chain of habitats which run
144-458: A vivid contrast to the burnt brown of the Marlborough hills. A fault running underneath Lake Grassmere triggered a magnitude 6.6 earthquake on Friday, August 16, 2013 at 2:31:05 pm. The quake was 8 kilometres (5 mi) deep and was strike-slip fault similar to the 2013 Seddon earthquake on July 21, thus considered a doublet earthquake . The official name of the lake become a dual name as
168-453: A year after Ngāti Toa under the leadership of Te Rauparaha had defeated Ngāi Tahu at Kaiapoi and Banks Peninsula , Ngāti Toa visited the lake to take moulting ducks. A Ngāi Tahu force, having learned of this impending visit, laid an ambush. Scouts from Te Rauparaha's party found the locality apparently uninhabited and the canoes were driven ashore. On landing, the visitors were taken by surprise and sustained heavy casualties. Te Rauparaha
192-453: Is 4 metres (13 ft) above sea level . 2013 Lake Grassmere earthquake The 2013 Lake Grassmere earthquake was a magnitude 6.6 earthquake that occurred at 2:31:05 pm (NZST) on Friday 16 August 2013. The epicentre was located about 10 km south-east of Seddon , under Lake Grassmere , with a focal depth of 8 km. The earthquake caused significant land damage in the local area, with landslips blocking roads, including
216-466: Is extracted. These crystals give the lake a distinctive pink colour. Grassmere's area varies between 3,500 and 4,400 acres (14 and 18 km); this maximum is attained only in rare floods. The watershed is small. The climate, with a low average rainfall of 585 millimetres (23.0 in) and prevailing strong and dry north-westerly winds, provides Lake Grassmere with the suitable conditions required for natural economic salt production. The Māori name for
240-531: Is fed by two small rivers, Selwyn River / Waikirikiri and Irwell River . These bring it a, comparatively, low volume of water, along with loads of silt and sand. At the coast, in an area known as Canterbury Bight , a current runs parallel to the shore from south to north. This strong current brings with it sand and gravel sourced from the Rakaia River . The bight is chronically eroding because its beaches are starved of sediment. The Rakaia River, incidentally, has
264-608: Is on the north-easterly extension of the Ward depression. Covering an area of 17 square kilometres (6.6 sq mi), it has no natural inflow and is prone to strong warm winds. Close to the sea, it also has very high salinity . Because of these geographical characteristics, it is ideal for natural salt extraction. Grassmere has been divided into solar evaporation ponds. Seawater is pumped in, and moved between ponds over several months, increasing in salinity with each evaporation period. As salinity increases, crystallised salt forms and
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#1732851988624288-491: Is solar salt, and both iodised and non-iodised table salt are available. Iodised salt contains added iodine (to prevent goitre ) and silicon dioxide (to make the salt run). Specialty salts, including flaky salt, are also produced at Lake Grassmere. Animal health products such as salt licks for farm animals are produced at Grassmere and Mt Maunganui. At the end of summer Grassmere's gleaming white salt piles are easily seen from State Highway 1. This seasonal landmark forms
312-449: The distal end. It's become a barrier. Approximately 5000 years ago, it swung around, hinged at the point near Wairewa marae on the shores of Lake Forsyth / Waiwera . The barrier, named Kaitorete Spit , even though it's a barrier not a spit, prevents the Selwyn / Waikirikiri and Irwell rivers from draining into the sea, and hence, a waituna sits behind the barrier. Its natural lake level
336-556: The July and August earthquakes. The quake caused substantial damage to a number of residential homes in the Seddon area. Eight houses were evacuated by The Marlborough District Council and another 11 allowed only restricted access. The quake was felt as far north as Auckland and far south as Dunedin . Damage was reported in the Kāpiti Coast , Hutt Valley , Wellington, Blenheim , Ward and
360-508: The city for a couple of hours. The City Council ordered the deconstruction of a 30-year-old lift shaft that had been damaged in a previous earthquake in July, after recently installed emergency seismic restraints failed. Several surrounding buildings in the fall zone were ordered to be evacuated. In the Wellington Region, 2,500 homes were left without power immediately after the earthquake. Most homes had power restored within an hour. Power
384-609: The first few hours after the main shock. The earthquake generated a significant series of aftershocks, the largest of which had a magnitude of 6.0. Below is a list of all aftershocks magnitudes 5.0 and above that occurred in the region between 16 August 2013 and 5 September 2013. In Wellington, the earthquake caused minor damage to buildings, breaking some display windows and cracking plaster. Many central city office workers left work early, and with all suburban train services cancelled for urgent track inspections, bus services overloaded and traffic gridlock occurred on major roads out of
408-422: The lake is Kapara Te Hau ("wind-blown lake"). Early whalers on the coast rendered this name “Cobblers' Hole”. According to Māori oral tradition, the lake occupies the site of early cultivations. Kupe , the navigator, is said to have poured salt water on these cultivations, thus creating the lake. In pre-European times it was used as a ready source of food, as it attracts a wide range of waterfowl. In 1832–33,
432-932: The length of the east coast of the South Island : from Wairua Lagoon and Lake Grassmere / Kapara Te Hau in Marlborough , through Lake Ellesmere / Te Waihora and Coopers Lagoon / Muriwai in central Canterbury , and Washdyke Lagoon and Wainono Lagoon in South Canterbury, to Waituna Lagoon in Southland . Waituna Lagoon is one of the finest examples. The name translates as “water of eels”. Both waituna and hapua are fed by small rivers flowing out to an MSG beach, on an eroding wave-dominated coast, with strong longshore drift. Hapua are long-lived river mouth lagoons, whereas waituna are ephemeral coastal "lakes" that do not persist over geological time. Hapua persist because
456-622: The main highway between Blenheim and Christchurch. Buildings in Seddon were damaged, with some being declared uninhabitable. The earthquake was widely felt in both the North and South Islands of New Zealand. This earthquake is considered to be a doublet of a magnitude 6.5 earthquake that occurred in Cook Strait on 21 July 2013 and is thought to have occurred on part of the same complex of faults. It started its own aftershock sequence, with several magnitude 5 and one magnitude 6 earthquakes occurring in
480-480: The river mouth turns sideways and carves out cliffs on a daily basis, whereas waituna form when gravel creates a barrier that impedes the drainage of freshwater. Natural openings through the barrier are rare, although artificial openings are common. Over geological time, provided natural coastal processes are able to operate unimpeded, the "lake" floods and infills, or the barrier disappears with coastal erosion. Waituna are low in salt, high in water that lies around for
504-433: The suitable lake area of 15 square kilometres (3,800 acres). The 1960 production was 17,000 tons. In addition to low rainfall, Grassmere is perfectly suited to solar salt production. In the mid 1960s harvests were carried out with a new pattern of crystallising ponds which have special provision for draining off rainwater before it has had time to mix with the brine concentrate. The harvest for 1964–65 reached 30,000 tons,
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#1732851988624528-564: Was built. This produced the high-purity salt needed by producers in the dairy and pharmaceutical industries. A second, smaller vacuum plant was built at Grassmere. Some rolling stock from the railway at Grassmere salt works is preserved at the Ferrymead Two Foot Railway . A large range of salts with slightly different chemical compositions, grain sizes and shapes are produced at Lake Grassmere. All table salt produced in New Zealand
552-533: Was restored to 7,500 properties in Wellington City, Kāpiti Coast and Wainuiomata by 5 pm. Phone lines were also overwhelmed. State Highway 1 between Blenheim and Kaikōura was closed for the night after the earthquake. Wellington Airport temporarily closed to check for runway damage. By July 2014, the Earthquake Commission had paid out a total $ 23.4 million for 8,221 claims in response to
576-406: Was seized by Tūhawaiki , who was anxious to take him alive. The captive, however, after feigning resignation, was less tightly held. He then slipped out of his flax garment, swam to a canoe and made his escape. Until the 1940s Grassmere's bed was a mud bath in winter and a dustbowl in summer, with the occasional natural deposit of salt. The salt industry began in 1943 and now occupies one-third of
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