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
Cincinnati and Whitewater Canal Tunnel with wing walls. Upon completion, the tunnel was long, and there was between the ceiling and the underwater bottom of the canal. Unusually, the tunnel included room for a towpath instead of requiring the use of leggers, but the typical canal boat nevertheless relied on manpower while allowing the beasts of burden to climb the hill. As the state's first tunnel of its type, the Cincinnati and Whitewater Canal Tunnel has suffered two separate collapse incidents. The first occurred during the construction process, and six workmen died, while another segment caved in during the 1950s during a project to improve