The Bonneville Salt Flats are remains of the vast lake Bonneville of the Pleistocene era. They are well known for the C20 obsession of land speed records. The close surroundings of the Salt Flats are marked by the exploits of the aptly named Intrepid Potash mining company. In recent years, some speed races were cancelled due to the thinning of the salt crust. Intrepid Potash is now required to pump brine on to the flats to mitigate the problem.