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Prominence Family Groups

There are 1564 Prominent Peaks in the UK and they fall into 4 prominence categories (P1000, P500, P200 and P100). The P1000s have descendants of P500/P200/P100. The P500s (on the GB mainland) have a P1000 ancestor and potential descendants of P200/P100. The P200s have potential P100 descendants and ancestors of P1000/P500. The P100s have only ancestors – although many have subsidiary summits (P50s) which do not meet our Prominent Peak qualification (P>=100). The analysis of the Prominent Peaks and their descendants looks like this:

One overview of the UK’s Prominent Peaks can be obtained by looking at the 3 P1000s (Ben Nevis, Carn Eige and Snowdon) and their family groups, together with the hills that do not have a P1000 as an ancestor.

Great Britain – P500 Families

All the UK’s P1000s are on mainland Great Britain. Each P1000 is the ancestor of a family of peaks, and this family defines a “footprint”. The Ben Nevis family has a total of 586 peaks.

The Ben Nevis family consists of all the Prominent Peaks south of the Great Glen and north of the Central Belt of Scotland. All hills in the Southern & Central Highlands, the Greater Cairngorms area and the Lowlands north of the Central Belt are in this family.

North of the Great Glen is the Carn Eige family that stretches from Morvern in the South to Sutherland and Caithness in the North. It includes the entire Western and Northern Highlands.

The Snowdon family consists of all Prominent Peaks south of the Central Belt of Scotland. This includes all the ranges of hills from the Pentlands near Edinburgh to Dartmoor. It includes all the Prominent Peaks in the Scottish Southern Uplands, England and Wales.

Northern Ireland

Islands

In this topographic respect the Islands are special and their remoteness and proximity of the hills to the sea makes them a unique challenge. Skye, Arran and Mull are popular hillwalking destinations.

Lake District

The Lake District can be used to illustrated P500 family groups. There are four P500s in the Lake District – Scafell Pike, Helvellyn, Skiddaw and Grasmoor. Each has a family of P200 and P100 peaks.

The Helvellyn family can be used to illustrate P200 family groups. The P200s, Fairfield and High Street have 2 and 6 descendants respectively. The other 3 P200s (Little Mell Fell, Place Fell and Red Screes) have no descendants. The 3 P100s lying north of Helvellyn have the P500 as their ancestor.

Unexpected Results

An examination of family groups often reveals some unexpected results. For example:

1. Broad Law (50km S of Edinburgh) is the highest summit in the eastern Lowlands but because of the height of Beattock summit, its footprint extends right over to the Nith valley and up to Greenock on the banks of the Firth of Clyde.
2. Families ignore national borders, with 8 summits entirely within Scotland in The Cheviot P500 family and 4 Shropshire summits in the Pen Pumlumon Fawr (Plynlimon) P500 family. Slieve Gullion in Northern Ireland has its P500 ancestor (Slieve Foye) in the Cooley Mountains in the Republic of Ireland.
3. Thanks to the guidebooks of Alfred Wainwright, many hillwalkers would expect the Dale Head group of hills to be part of the Grasmoor family, as together they make up most of the North-Western Fells in the Lake District. Because Honister Pass is higher than Newlands Pass, the 3 hills are in fact part of the Scafell Pike family (see slide above).
4. Whilst there are 15 P500s with no descendants, there are some with very many. The 5 P500s with the largest family groups are Ben Macdui (92), Broad Law (75), Lochnagar (62), Cross Fell (48) and Carn Dearg in the Monadh Liath (44). All these hills can be associated with large areas of high ground. Cross Fell has the largest footprint with a subsidiary prominent peak in Derbyshire some 170 km S. Indeed, it is possible to think of its footprint extending from the river Tyne to the Thames. Conversely, the P500 with the smallest footprint at 14 square kilometres is Stob Dubh on the E side of Glen Etive.