Conservatives until it was won by Labour in 1992, then taken by the Liberal Democrats in 2005 and 2010, before returning to Labour in 2015. A southern area of the city, Queen Edith's ward, falls within the South Cambridgeshire constituency, whose MP is Anthony Browne (Conservative), first elected in 2019. The University of Cambridge formerly had two seats in the House of Commons; Sir Isaac Newton was one of the most notable MPs. The Cambridge University constituency was abolished under 1948 legislation, and ceased at the dissolution of Parliament for the 1950 general election, along with the other university constituencies. Geography and environment Cambridge is situated about north-by-east of London and east of Birmingham. The city is located in an area of level and relatively low-lying terrain just south of the Fens, which varies between above sea level. The town was thus historically surrounded by low-lying wetlands that have been drained as the town has expanded. The underlying geology of Cambridge consists of gault clay and Chalk Marl, known locally as Cambridge Greensand, partly overlaid by terrace gravel. A layer of phosphatic nodules (coprolites) under the marl was mined in the 19th century for fertiliser; this became a major industry in the county, and its profits yielded buildings such as the Corn Exchange, Fulbourn Hospital, and St. John's Chapel until the Quarries Act 1894 and competition from America ended production. The River Cam flows through the city from the village of Grantchester, to the southwest. It is bordered by water meadows within the city such as Sheep's Green as well as residential development. Like most cities, modern-day Cambridge has many suburbs and areas of high-density housing. The city centre of Cambridge is mostly commercial, historic buildings, and large green areas such as Jesus Green, Parker's Piece and Midsummer Common. Some of the roads in the centre are pedestrianised. Population growth has seen new housing developments in the 21st century, with estates such as the CB1 and Accordia schemes near the station, and developments such as Great Kneighton, formally known as Clay Farm, and Trumpington Meadows currently under construction in the south of the city. Other major developments currently being constructed in the city are Darwin Green (formerly NIAB), and University-led developments at West Cambridge and North West Cambridge, (Eddington). The entire city centre, as well as parts of Chesterton, Petersfield, West Cambridge, Newnham, and Abbey, are covered by an Air