BIG Pit, BLAENAVON A NEW CHRONOLOGY? by J. A. H. EVANS Introduction Big Pit colliery, Blaenavon, has become one of the leading Industrial Museums in Britain. When it stopped producing coal in 1980 it was regarded as the oldest working pit in South Wales. Its unique attraction in South Wales is that visitors can still travel down the pit shaft and visit the underground workings. The pit is regarded as unusual because it has one large elliptical shaft in which the pit cages pass each other rather than the usual arrangement of two separate round ones. The large shaft, which eventually gave the pit its name, is 18 feet by 13 feet in diameter and 293 feet deep. Visitors are told that the pit was originally known as Kearsley's Pit and that it was sunk around 1860. It is claimed that the shape of the pit was changed to elliptical from a single round shaft when the pit was enlarged and sunk to a greater depth when production of coal increased sometime between 1860 and 1880. Much of the information given to visitors is from local tradition but the date of the pit is taken from the excellent illustrated booklet Big Pit, Blaenafon written by Dr W. Gerwyn Thomas, originally published by the National Museum of Wales in 1981.2 There is reliable map evidence that the pit was sunk to a greater depth in around 1880, but was it widened to its elliptical shape at that date? Why are there no records of it at all, except for plans until the 1880s and why was it not apparently used until that time? This article will question both the dating of the pit and the explanation put forward for its elliptical shape. It will attempt to answer why and when it was originally called Kearsley's Pit and in so doing suggest that the pit was sunk much earlier than previously thought. Dr W. Gerwyn Thomas based the date that he ascribed to the sinking of the pit on the quite logical assumption that it would have been sunk during the construction of Blaenavon Company's3 new forge at Forgeside around 1860. The date used by Dr Thomas was the date that the forge was put into production. It had been in the course of erection since around 1837. This phase of construction had commenced in 1853. He also made use of a plan of the surface of the pit drawn by David Davies, the Blaenavon Company surveyor, dated 18 November 1862.4 Kearsley's Pit is shown with only a circle to represent the shaft and no indication of a winding engine or other buildings nearby. The pit was connected at the pit bottom to a level known as Forge Level. This level also connected to the bottom of Forge Pit, which once stood just below Big Pit, and continued down the mountain until it opened out on the west bank of the river Afon Llwyd.