What prominence (drop) means, with real figures
Prominence, called drop in the British and Irish hill lists, is the height of a summit above its key col: the lowest point you must descend to before you can climb to anything higher. It measures how much a hill stands out rather than how high it is. Across the 1,140 hills on this site the median drop is 236.9 m, 885 have at least 150 m, and only four exceed 1,000 m.
The key col, with an example
Picture walking from a summit to the nearest higher ground by whichever route loses the least height. The lowest point on that route is the key col, and drop is summit minus col. For a small top on a ridge the col may be a few metres below the cairn and a few hundred metres away. For a big mountain it can be a long way off.
Scafell Pike is the clearest case. It stands 978.1 m high, and its key col is at only 65.9 m, at grid reference SJ 6368 3387, 178.4 km south of the summit. That gives a drop of 912.2 m, or 93.3% of its height. To reach higher ground from England's highest point you would have to come down almost to sea level and travel to Wales; the nearest higher summit is Carnedd Llewelyn.
When the col is at sea level the drop equals the full height. That is true of 11 hills here: Ben Nevis, Sgurr Alasdair, Askival, Ben More (Argyll and Bute), Beinn an Oir, Goatfell, An Cliseam, Beinn Mhor (Na h-Eileanan Siar [Western Isles]), Snaefell, Carrauntoohil and Croaghaun. Ben Nevis and Carrauntoohil are the highest points of Great Britain and Ireland, and the others are the highest points of smaller islands, so there is no higher ground to connect to without crossing the sea.
What a typical drop looks like
The chart is lopsided. A large group sits below 100 m, mostly Lake District fells and other small tops; a broad hump runs from 150 m to about 400 m, which is where most Marilyns of 600 m or more fall; and a thin tail stretches out to Ben Nevis. Half the hills rise less than 236.9 m above their col.
| Drop | Hills | Share of 1,140 | |
|---|---|---|---|
| 15 m or more | 1,108 | 97.2% | 1,108 hills (97.2%) |
| 30 m or more | 1,081 | 94.8% | 1,081 hills (94.8%) |
| 150 m or more | 885 | 77.6% | 885 hills (77.6%) |
| 300 m or more | 437 | 38.3% | 437 hills (38.3%) |
| 500 m or more | 187 | 16.4% | 187 hills (16.4%) |
| 1,000 m or more | 4 | 0.4% | 4 hills (0.4%) |
Hills on this site with at least the given drop. Thresholds of 15, 30 and 150 m are the drop rules of the Nuttalls, Hewitts and Marilyns.
Drop by hill list
County tops come first: the highest point of a county is often a big, free-standing hill, even though the list has no drop rule. Corbetts and Grahams, the two height-band lists that require about 150 m of drop, follow. The Munros, with no drop rule, come next, and the Wainwrights and Nuttalls, which count small tops, come last.
| List | Median drop | Median height | |
|---|---|---|---|
| County tops | 335.6 m | 622 m | Median height 622 m |
| Corbetts | 300 m | 835 m | Median height 835 m |
| Grahams | 256 m | 690.3 m | Median height 690.3 m |
| Munros | 245.7 m | 999 m | Median height 999 m |
| Marilyns | 226.5 m | 549 m | Median height 549 m |
| Donalds | 116.5 m | 684.6 m | Median height 684.6 m |
| Hewitts | 108 m | 699.5 m | Median height 699.5 m |
| Furths | 95.3 m | 959.9 m | Median height 959.9 m |
| Wainwrights | 60.3 m | 657.5 m | Median height 657.5 m |
| Nuttalls | 57.7 m | 700 m | Median height 700 m |
Median of every hill on each list in the database, not only those profiled here.
Why England's figures are low
The median drop of the hills profiled here is 362.5 m in Ireland, 284 m in Wales and 263 m in Scotland, but only 72 m in England. The reason is the selection, not the landscape: 214 of England's 242 hills on this site are Wainwrights, which are included whatever their drop. The other 28 English hills, all Marilyns, have a median drop of 276 m.
Drop as a share of height
Every hill page also gives drop as a percentage of height. A share near 100% means a hill rises almost from sea level; a share near zero means it is a bump on a larger mass. The median share across the site is 31.4%. At the bottom are High Pike (Scandale) and Bonscale Pike, each at 0.2%: a drop of 1 m on a hill of hundreds of metres.
The greatest drops
| No. | Hill | Drop | Height | Country | |
|---|---|---|---|---|---|
| 1 | Ben Nevis | 1,344.5 m | 1,344.5 m | Scotland | Height 1,344.5 m · Scotland |
| 2 | Carn Eighe | 1,147 m | 1,182.8 m | Scotland | Height 1,182.8 m · Scotland |
| 3 | Snowdon – Yr Wyddfa | 1,039 m | 1,085 m | Wales | Height 1,085 m · Wales |
| 4 | Carrauntoohil | 1,038.6 m | 1,038.6 m | Ireland | Height 1,038.6 m · Ireland |
| 5 | Sgurr Alasdair | 992 m | 992 m | Scotland | Height 992 m · Scotland |
| 6 | Ben More (Stirling) | 986 m | 1,173.9 m | Scotland | Height 1,173.9 m · Scotland |
| 7 | Ben More (Argyll and Bute) | 966 m | 966 m | Scotland | Height 966 m · Scotland |
| 8 | Liathach – Spidean a' Choire Leith | 957 m | 1,054.8 m | Scotland | Height 1,054.8 m · Scotland |
| 9 | Ben Macdui | 950 m | 1,309.3 m | Scotland | Height 1,309.3 m · Scotland |
| 10 | Brandon Mountain | 927 m | 951.7 m | Ireland | Height 951.7 m · Ireland |
| 11 | Ben Lawers | 914 m | 1,214.3 m | Scotland | Height 1,214.3 m · Scotland |
| 12 | Sgurr Mor (Highland, NH203718) | 914 m | 1,108.9 m | Scotland | Height 1,108.9 m · Scotland |
The twelve hills on this site with the greatest drop.
Small drops are the figures most sensitive to measurement, because a change of a metre or two at either the summit or the col changes the result by the same amount. Treat a drop of a few metres as approximate, and a hill a metre either side of a list threshold as a borderline case.
In the finder: list the 187 hills with a drop of 500 m or more
Isolation, the distance to higher ground, is the other half of the picture; read The most isolated hills in Britain and Ireland.
Sources
- Contains data from The Database of British and Irish Hills v18.6 (www.hill-bagging.co.uk/dobih), licensed under CC BY 4.0. Distances, ranks and comparisons are our own calculations. hill-bagging.co.uk/dobih, licence.
- How drop, isolation and ranks are worked out: Data & methodology.