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
Canal tunnel Canal tunnel A canal tunnel is a tunnel for a (shipping) canal. The longest canal tunnel in the world is the Rove Tunnel in France, currently disused. The proposed Stad Ship Tunnel in Norway, while shorter, will be significantly wider and deeper, as it is designed to accommodate seagoing vessels. The oldest canal tunnel in the world is the Malpas Tunnel also in France, built in 1679. In some canal tunnels the towpath continues through the tunnel. In other cases, especially on English narrow canals, there is no towpath. The horse would be led over the hill and the boat