Rock Salt EarthCache
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You are looking at the Lindbergh Salt Plant jest north of the North Saskatchewan river. Most of the Windsor-brand table salt you use to season your food is actually not mined in Windsor, Ontario, but in Lindbergh, Alberta. This mine produces about 400 tonnes of halite, or rock salt, per day.
In 1946 a companies drilling for oil and gas in the area accidently discovered a thick bed of rock salt.
The story of where the salt come from
During the Devonian Period, some 375 million years ago, rising sea levels sent sea water flooding across much of Western Canada. This shallow are of the ocean, called the Elk Point Basin, was bounded on the east by the Canadian Shield and on the west by the Western Alberta Arch, a long narrow peninsula that extended from Montana to the Peace River District. These warm, tropical waters teemed with marine life and both corals and stromatoporoids established reefs in many parts of the basin.
A rock arch near the south shore of what is now Great Slave Lake left the water shallow enough for stromatoporoids and corals to build the Preaqo'ile Barrier Reef. The reef blocked circulation of sea water from the open ocean into the shallow basin and in the arid climate, water evaporated and the salinity increased until most sea life was killed. Special minerals, called evaporates, came out of solution and settled as a layer on the basin floor. A 100-metre column of sea water will produce only 0.5metres of evaporates and in Alberta, evaporates, mainly rock salt,
reach thicknesses of over 400 metres. This means that in order to reach such thicknesses, fresh supplies of sea water must have flooded into the basin numerous times. Evaporites from in an ordered sequence- first to form are the sulphates (gypsum and anhydrite),then halite, and finally the bitter dregs of potassium salt (potach). The Saskatchewan portion of this basin contains ove 50per cent of the world reserves of potash which is used in the making of fertilizers.
At Lindbergh the salt is located over 1100 meters below plant and is brought to the surface by a technique called "solution mining". This done by drawing nine million liters of water per day from the North Saskatchewan River and then pumping it down wells to the salt beds. The water warms as it descends, dissolves the salt and is then pumped up another wall. Each 10 liters of water carries over 2.75 kilograms of salt, which is pumped into large pans and steam-heated in evaporators until 99.8 per cent pure salt is left.
The Windsor company believes there is enough salt beneath Lindbergh to last another 2000 years.
To log this cache email, do not post the answers to the following questions to the cache owner;
You do not have to go onto Winsors property to answer these questions.
1] What is the other name for rock salt?
2] What is the depth of the rock salt deposit?
3] Each 10 liters of water carries over ___ ? kilograms of ___?
4) In 1946 the company drilling for oil and gas would dump the unwanted rock salt by and in the small creek to the East of ground zero. Has this part of the salt plant recovered, and is there any sign of contamination by looking at the trees and plant growth?
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