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
Eyre's Tunnel passes above the tunnel. Eyre's Tunnel Eyre's tunnel or Lisson Grove Tunnel is a short canal tunnel on the Regent's Canal that passes under Lisson Grove in St John's Wood, north London and opened in 1816. It is only 48 metres long. The two other tunnels on the Regent's Canal are Islington Tunnel and Maida Hill Tunnel. Unlike the other tunnels, Eyre's Tunnel has a (now fenced) towpath. The tunnel was originally known as Eyre's Tunnel due to its passing beneath land belonging to Richard Eyre, a local landowner. Lisson Grove is a more recent usage clearly following the renaming