Task: Question Generation
Input (English): Passage: Chat Moss may be named after St Chad, a 7th-century bishop of Mercia, but as it was once part of a great tree-edged lake, as evidenced by the numerous wood remains in the lower levels of the peat, it is perhaps more likely that the name stems from the Celtic word ced, meaning wood. Chat Moss could also derive from Ceatta, an Old English personal name and mos, a swamp or alternatively the first element could be the Old English ceat meaning a piece of wet ground. It was recorded as Catemosse in 1277 and Chatmos in 1322. Moss is the local name for a peat bog.Daniel Defoe visited the area in 1724, on his way from Warrington to Manchester:
From hence (Warrington), on the road to Manchester, we pass'd the great bog or waste call'd Chatmos, the first of that kind that we see in England ...
The surface, at a distance, looks black and dirty, and is indeed frightful to think of, for it will bear neither horse or man, unless in an exceeding dry season, and then not so as to be passable, or that any one should travel over them ... What nature meant by such a useless production, 'tis hard to imagine; but the land is entirely waste, excep ... for the poor cottagers fuel, and the quantity used for that is very small.
Peat bogs sometimes burst their boundaries, particularly after being subjected to heavy rainfall, and this seems to have happened with Chat Moss in the 16th century. John Leland, writing during the reign of King Henry VIII, described one such event:
Chat Moss brast up within a mile of Mosley Haul, and destroied much grounde with mosse thereabout, and destroyed much fresh-water fishche thereabout, first corrupting with stinkinge water Glasebrooke, and so Glasebrooke carried stinkinge water and mosse into Mersey water, and Mersey corrupted carried the roulling mosse, part to the shores of Wales, part to the isle of Man, and some unto Ireland.
Chat Moss presented a significant challenge to the engineers constructing the Liverpool and Manchester Railway in 1826 because of the difficulty in providing a solid base for the track, in particular at a location known as Blackpool Hole. George Stephenson  was the engineer in charge of the project, and his initial idea was to dump enough spoil in the bog so that it would reach the bottom. This approach turned out to be impractical however, as the liquidity of the bog allowed the spoil to flow away from where the track was to be laid. The eventual solution, to build the line on a "floating" wood and stone foundation, was hailed as a "great triumph of engineering". The first train ran through Chat Moss in 1830, and the line is still in use today.
Output (English): Which portion of Chat Moss posed the biggest difficulty in building the railroad?