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 would be propelled by legging. The term "canal tunnel" does not seem to be commonly applied to tunnels used to conduct water (for irrigation, water supply, etc.), such as the 48-kilometre-long Arpa-Sevan tunnel in Armenia (see List of longest tunnels), or a number of tunnels on the Irtysh–Karamay–Ürümqi Canal in China. For those, the term water tunnel is more commonly used. Canal tunnels were made in the Kingdom of Travancore as early as 1876. 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