Bloomer’s Challenge is based on the UK Prominent Peaks database. The database divides the Prominent Peaks into four prominence groups known as P100, P200, P500 and P1000. The qualifying criterion for the list is a minimum prominence of 500 metres, in other words comprises the P500 and P1000 peaks in the database.
This prominence criterion is much more demanding than that of any existing UK hill list The well known Relative Hills of Britain or Marilyns are based on a prominence criterion of 150 metres, thus all P500+ peaks are also Marilyns.
A prominence of 500 metres or more ensures that a peak is distinct and well differentiated from any neighbours in the list. This applies whether the peak rises from a plateau, as in the Cairngorms, or from close to sea level on an island.
If the Bloomer’s Challenge list is viewed using Google Maps or Google Earth icons are used to distinguish between P1000 peaks (blue) and P500 peaks (red).
A different icon shape is used to distinguish between different height groups.