Over the years there have been numerous attempts at defining what consitutes a mountain or summit. There are numerous different classification systems, all of which are valid in their own right.
For people, like myself, who love the challenge of collecting summits the resulting hill lists provide a long term goal to aim for.
The following pages provide a brief introduction to each classification system along with a list of the relevant Pennine tops that come under that particular list.
Marilyns are a mountain or hill with 150m (492ft) of relative height regardless of absolute height.
Hewitts are hills over 2000ft (609.6m) with a relative height of at least 30m (98ft).
Nuttalls are hills over 2000ft (609.6m) with a relative height of at least 15m (49ft).
Deweys are hills between 500m (1640ft) and 609m (1999ft) with a relative height of at least 30m (98ft).
County Tops are basically the heighest point in a county. The list is split into historic county tops, the 1974 administrative county tops and current county and unitary authority tops.
The Database of British Hills website features the most up to date information on the above lists.