Ancient desert seas
Around 240 million years ago a shallow desert sea extended from what is now North Yorkshire and the North Sea into present day Germany. As the sea water evaporated various salts were deposited which would eventually form the basement rocks of the North York Moors.
Although not exposed on the surface in North Yorkshire, the existence of these valuable salts has been known for many years and their commercial value appreciated, principally for agricultural use and road salt.
Occurring at a depth of around 1000 metres the exploitation of the salts was technically difficult and not economically viable until the late 1960s. Three companies then applied successfully for planning permission to mine the resource but only one went into production, in 1973.
The decision to allow mining was controversial as the site lay within the North York Moors National Park and also a proposed Heritage Coast (confirmed in 1974) The final decision was made at Government level but not before many conditions imposed, particularly concerning the environment.
It's warm down there!
Cleveland Potash operates the mine at Boulby, the only potash mine in Britain and the deepest in Europe. One million tons of potash and half a million tons of salt are mined annually and the mine employs nearly 1000 people. The mining operation extends for several miles underground and under the North Sea. As the rocks dip to the south the distance between the surface and the mine workings gets deeper, well over 1400 metres.
90% of our universe in missing!
And in order to find it, astro-physicists have set up a laboratory 1100 metres underground at the bottom of Boulby potash mine. Sheltered from cosmic rays they hope to discover more about 'WIMPS' , Weakly Interactive Massive Particles or 'Dark Matter' which could tell us where to find the rest of our universe!