Understanding the Peak Data

Header Categories

All 3 downloadable hill lists have 24 columns. The left part of the spreadsheet header is shown below.

Left side of spreadsheet

From left to right these columns are:

Prominence Rank – This ranks the hills by prominence. Ben Nevis is 1, Carn Eige 2, Snowdon 3, etc

Prominence – this gives the prominence of the hill in metres above its key col. For Y Lliwedd, this is 154 metres.

Height – This is the elevation of the highest (natural) point on the hill. Large cairns and other manmade structures are ignored. For Snowdon the height is 1085 metres.

Dominance (%) – This is calculated by dividing Prominence by Height and expressing the result as a percentage. The highest peak on any landmass will have a dominance of 100%. Ben Nevis, Goat Fell (Arran), Snaefell (IOM) and the highest peaks on 6 other islands have a dominance of 100%. The peak with the second highest dominance on the GB mainland is Sgurr Dhomhnuill in Ardgour (Dominance 98%, Prominence 873 m, Height 888 m). The UK Prominent Peak with the lowest dominance is Sgor an Lochain Uaine (Dominance 9%, Prominence 118 m, Height 1258 m).

Peak Name – Usually this comes from the Ordnance Survey. Where there are a number of names used for a hill, no attempt has been made to include the alternatives. The cells are colour coded according to prominence group (blue P1000, red P500, yellow P200 and green P100).

Country – England (E), Isle of Man (M, but definitely not a ‘country’ and strictly not part of the UK but included none the less), Northern Ireland (NI), Scotland (S) & Wales (W). The Schil, Windy Gyle and Carter Fell (all P100s) are on the Anglo/Scottish border but only appear once in the database as English. Black Mountain (another P100) on the Anglo/Welsh border similarly appears only once but as Welsh. Cuillagh, (a P500) in Fermanagh, shares its summit with The Irish Republic.

Location – here we use a variety of sources to identify where the hill is. Michael Dewey’s Groups are used extensively in England and Wales. In Scotland, the Chapter titles from early editions of the Scottish Mountaineering Club Guides are used as are Alan Dawson’s Section descriptions from his Marilyn lists, together with some new ones where this is considered appropriate. In Northern Ireland the Mountain Views website has been used.

Map 1:50,000 – In Great Britain and the Isle of Man, this shows the OS Landranger map sheet number or numbers. In Northern Ireland, the sheet number for the Ordnance Survey of Northern Ireland Discoverer map is shown.

Map 1:25 000 - In Scotland, England and Wales this shows the Explorer map sheet number or numbers.

Grid Ref – This is the Grid Reference which links the summit position to the kilometre squares on maps. For those using a hand held GPS device a 10 figure Grid Reference is provided. Non GPS users can ignore the 4th, 5th,9th and 10th digits which are produced in a smaller font size. When no data other than a 6 figure Grid Reference is available then the 4th, 5th,9th and 10th digits are shown as AB XXX50 XXX50. In this case GPS users will be guided to the centre of a 100 m square in which the summit resides. Some Northern Ireland grid references have been estimated and due caution should be exercised.

Section – This relates to the ‘Sections’ used by Alan Dawson in his Marilyn lists, which themselves are an extension of Sections 1-17 from the Scottish Mountaineering Club’s Munros Tables. Dawson’s Sections have been further extended by Clem Clements in his Marilyns of Ireland list. The best way to understand the relevant areas is to 'click' the link to Google Maps in the Database List. Sections 1 and 10 are subdivided and Sections 38, 40 & 41 are combined. Sections 22, 23, 25, 37, 39 & 42 do not appear as they have no summits of 500m elevation.

The right part of the spreadsheet header is shown below.

right side of spreadsheet

Peak Number and Section Order – These are both devices for Excel users to order the data topographically so that family groups with ancestors and descendants are clearly visible. Hills are placed in a ‘narrative order’, although this never undermines prominence hierarchies. The user can choose between a new peak order (link to further down page) system developed for the UK Prominent Peaks or opt to view data in an order governed by the P500s within Alan Dawson’s and Clem Clements’s sub-sections. The original data order is based on Peak Number and can be re-instated by highlighting any cell in the List, then clicking “Data”, then “Sort”, then setting the following priority: Peak Number (Smallest to Largest). To change to a section-based order, again highlight any cell, click "Data", then "Sort" then: Section Order (Smallest to Largest). The P200 and P100 peaks are in an identical order beneath their P500 ancestor, whichever order is chosen.

Family Size – There is a figure in this column whenever a hill has a Prominent Peak descendant. Ben Nevis has the most descendants (585) and with itself constitutes a P1000 family of 586. There are 154 summits with a Family Size of 2 and 1158 hills have no descendants. For those using the Thousanders List, the figures shown relate only to hills over 1000 m elevation.

Date Ascended – For Excel users of the Database List, there is an opportunity to input your Date Ascended (e.g. 01/01/2001), which then activates the ‘My Progress’ and ‘My Progress – Cumulative’ sheets.

Prominence Group – This shows the hill category grouped by database prominence criteria – P100, P200, P500 or P1000.

Height Group - This shows the hill category by database height criteria - H500, H750 or H1000.

Traditional List – Here the traditional category of the hill is given. Some 111 hills in Northern Ireland and Scotland appear in the Database List as ‘unclassified’ as they have not appeared in any popular listing thus far. There are 1007 Marilyns in the Database List but only 186 are shown as such (together with 22 Sub-Marilyns), as priority is given to hill categories with higher height qualification criterion.

Notes – These are definitely not exhaustive. An attempt has been made to give ‘links’ to access information for hills that fall in M.O.D. property and to identify those hills where the easiest route to the summit in ideal summer weather conditions may still present real difficulty to many hillwalkers.

Google Maps – This is a ‘link’ to Google Maps where icons show the position of all Prominent Peaks in the relevant Section(s) or Sub Section. The icons are colour coded in relation to different Prominence Groups and vary in size and height dependent on the Height Group of the hill.

P1000 P500 P200 P100
H1000 map icon H1000 P1000 map icon H1000 P500 map icon H1000 P200 map icon H1000 P100
H750 N/A map icon H750 P500 map icon H750 P200 map icon H750 P100
H500 N/A map icon H500 P500 map icon H500 P200 map icon H500 P100

See our guidance on Google Maps for more information

Streetmap – This link is to the Ordnance Survey’s 50 000 mapping which shows 12 square kilometres with each summit close to the centre. Northern Ireland is not included.

Get-a-map – This link is to the Ordnance Survey’s 25 000 service, showing 4 square kilometres around the summit.

Wikipedia – Another link takes you to the Wikipedia entry for the hill, where this exists.

Geograph – A final link takes you to the Geograph entry for the kilometre square in which the hill summit resides.

Peak Order

Peak order is dependent upon a new concept of 'Britain’s Hill Watershed', running from the Pentland Firth to the Bristol Channel. From Sutherland to the Peak District, this constitutes Britain’s East-West watershed and, after a dogleg to cross the Shropshire Union Canal, follows Wales’ East-West watershed. The route could be followed (in theory) by never crossing any rivers or streams and passing over the territories of just 39 P500s and Carn Eige (a P1000). Think of these 40 territories as the trunk of a tree. This 2 dimensional tree has branches and sub-branches to east and west, which again avoid rivers and streams. The diagram below shows Peak Numbers and does not differentiate between branches and their sub-branches except for Peaks 171 and 262 (the details for 262 remain an approximation).

trunk route table

Peak numbering starts at the top of the tree's trunk and works down, including all branches and their sub-branches as you go. This GB mainland tree makes up the first 3 parts of the Database. Peak Numbers 101-199 constitute Carn Eige and its descendants, Peak Numbers 201-298 the Ben Nevis Group and 304-388 Snowdon.

The 4th part (Peak Numbers 402 to 416) constitutes the 34 descendants of Carrauntoohil (P1000) in NI extracted from a similar ordering of All Ireland’s hills. The 5th Section (Peak Numbers 501 to 585) is made up of hills with no P1000 ancestor. These are, of course, the Islands beginning with Lewis/Harris through South Uist, Skye, Rum, Mull, Jura and Arran. The Peak Data ends on the Isle of Man. Neither the 4th or 5th parts are shown in the diagram above.