Blisworth Limestone Formation today in the seas off the Bahamas (Kirkaldy p. 59). Much of it also contains marine shells, notably of oyster. Subsequently, the site was submerged less deeply so that the overlying Blisworth Clay was deposited in brackish conditions. (Gallois p. 20) The stratum is known as Blisworth Limestone because it was first studied at Blisworth in Northamptonshire when the Blisworth tunnel was being dug for what is now called the Grand Union Canal. The tunnel finally opened in 1805. Blisworth limestone is a generally thin but widely spread deposit in eastern England. It becomes thicker as one progresses southward from
Harecastle Tunnel Harecastle Tunnel Harecastle Tunnel is a canal tunnel on the Trent and Mersey Canal in Staffordshire between Kidsgrove and Tunstall. The tunnel, which is long, was once one of the longest in the country. Its industrial purpose was for the transportation of coal to the kilns in the Staffordshire Potteries. The canal runs under Harecastle Hill near Goldenhill, the highest district in Stoke-on-Trent. Although described singularly as a tunnel, Harecastle is actually two separate but parallel tunnels built almost 50 years apart. The first was constructed by James Brindley in the late 18th century and the second larger tunnel was