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
Shrewley Tunnel Shrewley Tunnel Shrewley Tunnel is a canal tunnel near Shrewley, Warwickshire, England, which opened in 1799. It became part of the Grand Union Canal in 1929. The Warwick and Birmingham Canal Company obtained an Act of Parliament in March 1793, which authorised the construction of a canal from the Digbeth Branch Canal of the Birmingham Canal Navigations to Warwick, where it would end at Saltisford Wharf. The plans showed three tunnels, at Shrewley, Rowington and Yardley, but as construction progressed, the last two became deep cuttings. This was not an option at Shrewley, as the route passed under the village.