On 8 June 1850, the two of them walked the Cleveland Hills and quickly found a plentiful source, in the shape of the main seam of Cleveland Ironstone above sixteen feet (about five metres) thick. Bolckow and Vaughan moved rapidly: within 12 weeks, they had signed agreements with the landowners, started the first mine, built a tramway to carry the ironstone, and delivered the first load of seven tones to Witton Park.