Historically, in the Lake District of northwest England, travel on foot or by pony was difficult because of the region's steep-sided valleys so tracks across the ridges were created taking the easiest route over passes – often, but not always, via a col.
[1] About 500 million years ago[1] in the late Cambrian and early Ordivician periods,[2] the region was situated where the Iapetus ocean floor was being subducted under the Avalonia plate.
[8] When the Baltica-Avalonia and Laurentia continents collided some 420 million years ago in the Caledonian orogeny there was folding of the slate and fracturing (faulting) of the more brittle volcanic rock.
In the north, slaty rocks now form a smooth topography with sharp ridges although the hills can still be quite high – 931 metres (3,054 ft) in the case of Skiddaw.
Centrally the pyroclastic tuff rocks [1] give a knobbly terrain such as that around Scafell Pike, 978 metres (3,209 ft), England's highest mountain.
[1] Historically the region was suitable for sheep hill farming and from medieval (or possibly Roman) times there was a substantial mining industry for rocks and minerals.
With no roads suitable for wheeled traffic until the late 18th century, for long-distance transport of goods long trains of horses were used with ridge routes being preferred although Esk Hause and Stake Pass (see below) are thought to have been used in this way.
In the mid twentieth century Alfred Wainwright inadvertently encouraged further recreational use with his series of books A Pictorial Guide to the Lakeland Fells which described detailed routes to the major summits.
The hill passes listed are routes within the Lake District National Park between two different valleys where a pathway is marked on the Ordnance Survey 1:50000 or 1:25000 map.