The mountains and hills of the British Isles are categorised into various lists based on different combinations of elevation, prominence, and other criteria such as isolation.
There is no worldwide consensus on the definition of mountain versus a hill, but in Great Britain and Ireland it is usually taken to be any summit with an elevation of at least 2,000 feet (or 610 metres).
[3][4][5][6] The UK government legally defines mountain land as that over 600 metres (1,969 ft) for the purposes of freedom of access.
[9] No British Isles classification uses a quantitative metric of topographic isolation (such as the distance to the next point of equal height).
[15][16][17] It is maintained by a team of seven editors, and is described by the Long Distance Walkers Association as "now the most reliable online source for all Registers" (i.e. all lists of summits attained).
[15] The P600s are mountains in the British Isles that have a topographical prominence of at least 600 metres (1,969 feet), regardless of absolute height or other merits.
[24][25] Later, the Welsh peak Moel Siabod's prominence was remapped at 600 metres (2,000 ft) and the list of P600s expanded to 120.
[26] Although the margin of error means the result is not conclusive, it was accepted by Mark Trengove, who was present on the survey, bringing the total back to 119.
In February 2020 a GNSS survey of Beinn Odhar Bheag in conjunction with OS trig point data for Rois-Bheinn found the former to be 1 metre higher.
[28][29] The online version of The Database of British and Irish Hills also offers a P500 mountain classification: summits with a prominence above 500 metres (1,640 feet).
[30] The Marilyns are mountains and hills in the British Isles that have a topographical prominence above 150 metres (490 feet), regardless of absolute height or other merits.
[9] The Marilyns are one of the most popular lists for peak baggers, and because of the lack of any height threshold, the classification includes a wide range of hills and mountains, and some sea stacks (pictured right).
[40] The list was originally compiled by Sir Hugh Munro in 1891, and is modified from time to time by the Scottish Mountaineering Club (SMC),[14][41] an example being the delisting in December 2020 of Stob Coire na Cloiche as a Munro top, now recognised as being of only 912.5 metres (2,994 ft).
[44] The Murdos apply a quantitive criterion to the Munros and their associated tops, and comprise all of the summits in Scotland over 3,000 feet (914.4 m) with a prominence above 30 metres (98 ft).
[46][47] Alan Dawson first compiled the list in 1995 as an objective and quantitative alternative to the more qualitative SMC definition of a Munro.
[47] Dawson's threshold is in line with the 1994 UIAA declaration that an "independent peak" has to have a prominence of over 30 metres (98 ft).
[12] Unlike all other Scottish mountain and hill classifications, the SMC does not maintain an official list of Murdos.
[54] In 2004, Dawson published a list of Graham Tops covering every summit in Scotland between 2,000 and 2,500 feet (609.6 and 762.0 m) high with over 30 metres of prominence.
[60][61] Dempster describes them as "hills with attitude, not altitude" and says "the three key words are prominence, position, panorama".
[66] The Hewitts, named after the initials of their definition, are "hills in England, Wales and Ireland over two thousand" feet (609.6 m), with a relative height of at least 30 metres (98 ft).
Since their publication in 1997, Birks Fell and Calf Top in England and Mynydd Graig Goch have been added and Black Mountain deemed to be in Wales only.
[73][74] As of October 2018[update], 302 people are recorded as having completed the list, though this includes some who did not climb Pillar Rock, which the authors permit.
They have also announced that Tinside Rigg and Long Fell (added to the list in 2016) need not be summited as they are in a restricted area of Warcop Artillery Range.
[78][79] An exception was made for Castle Crag in Borrowdale, at 951 feet (290 m); Wainwright stated that although it was below his 1,000-feet criterion, it was a perfect mountain in miniature and demanded inclusion.
[119] The geographical coverage was originally confined to Britain, but was extended to the Isle of Man in February 2020 and to Ireland in September 2020.
[85][123][124] Bridge used a prominence threshold of 50 feet (15 m), but was hampered by the accuracy of the maps available at the time, and the list was effectively replaced by the Nuttalls, which uses the metric equivalent of 15 m – 49 ft.[87][124] The Database of British and Irish Hills recognises as Buxton & Lewis the 422 summits in Mountain Summits of England and Wales (1986) by Chris Buxton and Gwyn Lewis.
[85][125][126] Buxton and Lewis used a prominence threshold of two contour rings on the OS 1:50,000 map, and the number of hills is similar to the Nuttalls and the Bridges.
[127][128] The Database of British and Irish Hills recognises as Fellrangers the 230 (originally 227) Lake District summits in Mark Richards' Fellranger series of eight guidebooks (originally published by HarperCollins, starting with Central Fells ISBN 9780007113651; reprinted by Cicerone Press; 2013 boxed set ISBN 978-1852847487; new editions 2019–2021),[85][129] A list is available on the HillBagging website.
[131] The 2019-2021 edition includes a further three summits to bring the total to 230, the additions being Winterscleugh (Bretherdale Common), Whinfell Beacon and Grayrigg Forest, all in the Mardale and the far east volume.
His criterion was "an eminence which has an ascent of 100 m all round, or, failing that, is at least 5 km (walking distance) from any higher point on neighbouring hills".