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
Netherton Tunnel Branch Canal are joined at Windmill End Junction. The Boshboil Arm was once part of a loop of the original Dudley Canal which went around Bumble Hole. This loop ceased to be part of the main line when a more direct line was cut. The loop became severed into two arms as a result of subsidence. The northern arm is the Boshboil Arm the southern is the Bumble Hole Branch. Netherton Tunnel Branch Canal Netherton Tunnel Branch Canal, in the English West Midlands, is part of the Birmingham Canal Navigations, (BCN). It was constructed at a 453–foot elevation, the Wednesbury or Birmingham