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 the canal is in good repair and is used by boats accessing Hawne basin. The Lapal Canal Trust is concerned with restoring the lost canal to make it navigable up to the tunnel from both the Halesowen and Selly Oak ends, and originally had a longer term aim of restoring the tunnel. In May 2007 the trust received recommendations from professional consultants, Atkins, that the tunnel should not be restored but replaced by a new up-and-over alignment instead. In February 2012 plans for the regeneration of the Selly Oak area were submitted to Birmingham City Council which included a navigable