Lake Grassmere
Encyclopedia
Lake Grassmere is close to Cook Strait
in the northeastern South Island
of New Zealand
.
and 6 miles (9.7 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 is on the north-easterly extension of the Ward depression.
Covering an area of 17 km², it has no natural inflow and is prone to strong warm winds. Close to the sea, it also has a 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 successive evaporation period. As salinity increases, crystal
lised salt forms and is extracted.
Grassmere's area varies between 3,500 and 4400 acres (17.8 km²); this maximum is attained only in rare floods. The watershed is small. The climate, with a low average rainfall of 585 mm (24 in.) and prevailing strong and dry north-westerly winds, provides Lake Grassmere with the suitable conditions required for natural economic salt production.
name for the lake is Kaparatehau ("wind-blown lake"). Early whalers on the coast rendered this name “Cobblers' Hole”.
According to legend, 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, 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 was seized by Tuhawaiki
, 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.
The salt industry began in 1943 and now occupies one-third of the suitable lake area of 3800 acres (15.4 km²). 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, 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 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
.
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 a vivid contrast to the burnt brown of the Marlborough hills.
Cook Strait
Cook Strait is the strait between the North and South Islands of New Zealand. It connects the Tasman Sea on the west with the South Pacific Ocean on the east....
in the northeastern South Island
South Island
The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...
of New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
.
Geography
Lake Grassmere, 25 miles (40.2 km) south of BlenheimBlenheim, New Zealand
Blenheim is the most populous town in the region of Marlborough, in the north east of the South Island of New Zealand, and the seat of the regional council. It has a population of The area which surrounds the town is well known as a centre of New Zealand's wine industry...
and 6 miles (9.7 km) south of the mouth of the Awatere River
Awatere River
The Awatere River is a large river flowing through Marlborough, New Zealand. Flowing along the trace of the active Awatere Fault, it runs northeast through a straight valley to the west of the Inland Kaikoura mountains...
, is a shallow lagoon protected from the open sea by a single barrier beach covered by sand dunes. It is on the north-easterly extension of the Ward depression.
Covering an area of 17 km², it has no natural inflow and is prone to strong warm winds. Close to the sea, it also has a very high salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
.
Because of these geographical characteristics, it is ideal for natural salt extraction. Grassmere has been divided into solar evaporation
Evaporation
Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....
ponds. Seawater is pumped in, and moved between ponds over several months, increasing in salinity with each successive evaporation period. As salinity increases, crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
lised salt forms and is extracted.
Grassmere's area varies between 3,500 and 4400 acres (17.8 km²); this maximum is attained only in rare floods. The watershed is small. The climate, with a low average rainfall of 585 mm (24 in.) and prevailing strong and dry north-westerly winds, provides Lake Grassmere with the suitable conditions required for natural economic salt production.
Early history
The MaoriMaori language
Māori or te reo Māori , commonly te reo , is the language of the indigenous population of New Zealand, the Māori. It has the status of an official language in New Zealand...
name for the lake is Kaparatehau ("wind-blown lake"). Early whalers on the coast rendered this name “Cobblers' Hole”.
According to legend, the lake occupies the site of early cultivations. Kupe
Kupe
In the Māori mythology of some tribes, Kupe was involved in the Polynesian discovery of New Zealand.-Contention:There is contention concerning the status of Kupe. The contention turns on the authenticity of later versions of the legends, the so-called 'orthodox' versions closely associated with S....
, 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, a year after Ngāti Toa
Ngati Toa
Ngāti Toa , an iwi , traces its descent from the eponymous ancestor Toarangatira. The Ngāti Toa region extends from Miria-te-kakara at Rangitikei to Wellington, and across Cook Strait to Wairau and Nelson....
under the leadership of Te Rauparaha
Te Rauparaha
Te Rauparaha was a Māori rangatira and war leader of the Ngāti Toa tribe who took a leading part in the Musket Wars. He was influential in the original sale of conquered Rangitane land to the New Zealand Company and was a participant in the Wairau Incident in Marlborough...
had defeated Ngāi Tahu
Ngāi Tahu
Ngāi Tahu, or Kāi Tahu, is the principal Māori iwi of the southern region of New Zealand, with the tribal authority, Te Rūnanga o Ngāi Tahu, being based in Christchurch and Invercargill. The iwi combines three groups, Kāi Tahu itself, and Waitaha and Kāti Mamoe who lived in the South Island prior...
at Kaiapoi
Kaiapoi
Kaiapoi is a town in the Canterbury region of the South Island of New Zealand, located close to the mouth of the Waimakariri River, and approximately 17 kilometres north of Christchurch....
and Banks Peninsula
Banks Peninsula
Banks Peninsula is a peninsula of volcanic origin on the east coast of the South Island of New Zealand. It has an area of approximately and encompasses two large harbours and many smaller bays and coves...
, 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 was seized by Tuhawaiki
Tuhawaiki
Tuhawaiki — often known as Hone Tuhawaiki, John Tuhawaiki or Jack Tuhawaiki, or by his nickname of "Bloody Jack" — became a paramount chief of the Ngāi Tahu Māori iwi in the southern part of the South Island of New Zealand...
, 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.
Salt industry
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 the suitable lake area of 3800 acres (15.4 km²). The 1960 production was 17,000 tons.
- The total consumption of industrial and domestic salt in New Zealand in 1960 was about 61,000 tons.
- Maximum expansion could produce 50,000 tons, and many economic by-products can be developed; caustic soda and gypsum are already produced in small quantities.
- In 2005 Lake Grassmere provided about half of New Zealand's domestic salt requirements.
In addition to low rainfall, Grassmere is perfectly suited to solar salt production.
- The large area of flat land that makes up the lake bed is near the sea so it can draw in salt water, and away from large rivers.
- High evaporation from sun and wind occurs during summer, and the site has ready access to both sea and rail transport.
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, 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 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
Ferrymead Two Foot Railway
The Ferrymead Two Foot Railway Society Inc. is a member society of Ferrymead Heritage Park, in Heathcote, Christchurch, New Zealand. The society operates a two-foot gauge railway, on an oval circuit approximately 450M in length, at the Park...
.
Economics
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 is solar salt, and both iodised and non-iodised table salt are available.Iodised salt
Iodised salt
Iodised salt is table salt mixed with a minute amount of various iodine-containing salts. The ingestion of iodide prevents iodine deficiency. Worldwide, iodine deficiency affects about two billion people and is the leading preventable cause of mental retardation. It also causes thyroid gland...
contains added iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
(to prevent goitre
Goitre
A goitre or goiter , is a swelling in the thyroid gland, which can lead to a swelling of the neck or larynx...
) and silicon dioxide
Silicon dioxide
The chemical compound silicon dioxide, also known as silica , is an oxide of silicon with the chemical formula '. It has been known for its hardness since antiquity...
(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 a vivid contrast to the burnt brown of the Marlborough hills.
External links
- Salt making at Lake Grassmere in Te Ara - the Encyclopedia of New Zealand