Geography of Sheffield county, from bituminous (ideal for domestic heating) to "Thick Coal", of a semi-anthracitic quality, appropriate for use in iron-smelting and in engine furnaces. Associated with the Upper Coal Measures were valuable iron ore deposits, occurring in the form of nodules. Large quantities of locally occurring fireclay were also exploited, as well as ganister (a clay used to make refractory furnace linings). The city of Sheffield derives its name from the River Sheaf which Until the 17th century was written as "Scheth" or "Sheath". Sidney Oldall Addy equates the origins of this word with the Old English "shed" (as in "water-shed")
Sheffield City Airport the airport. However, the success of flights between Sheffield City and Amsterdam, and the subsequent expansion of regional airlines such as CityJet, Eastern Airways and Flybe, makes this debatable. It was also argued that Sheffield City Airport was unsuitable because the aircraft types used by the then-new low-cost airlines could not use the airport because of the length of its runway (which had proposed building a runway starter extension) – it was claimed that there was great demand for such services in the Sheffield area. However, the veracity of this argument has been thrown into doubt by the failure of