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
Chirk Tunnel completely unlit, it is preferable to use a torch/flashlight when walking through the tunnel, as towards the centre it is pitch black. There is however a wooden handrail along the entire length to prevent walkers falling in the canal. Chirk Tunnel Chirk Tunnel is a canal tunnel near Chirk, Wales. It lies on the Llangollen Canal, immediately northwards of the Chirk Aqueduct. It is long and has a complete towpath inside. The tunnel is designed for a single standard narrowboat, so passing is not possible. The tunnel is straight enough to be able to see if a boat is already