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
Lapal Tunnel section of canal from a new junction with the Worcester and Birmingham Canal to the recently reconstructed Harborne Lane bridge. Lapal Tunnel The Lapal Tunnel (old spelling Lappal Tunnel) is a disused canal tunnel on the five mile dry section of the Dudley No. 2 Canal in the West Midlands, England. It takes its name from the settlement of Lapal. The narrow brick-lined tunnel, built in 1798 by William Underhill, had no towpath. It had a very small bore - at 7 feet 9 inches, barely wider than the boats which used it, with a headroom of only 6 feet.