From UMHC Hiking Guide
The character of the Yorkshire dales is formed by their combination of limestone features with moorland scenery. The limestone features are most evident in the south of the dales both around Malham in the spectacular features of Attermire scar, Malham Cove and Gordale scar and in the Ribblesdale hills typically visited from Horton & Ribblehead or Ingleton.
These hills of Whernside, Pen-y-Ghent and Ingleborough are typified to some degree by large limestone plateaux around a height of 3/400 meters combined with caps of gritstone rising to around 700 meters. The distinctive character of these peaks combined with their closeness has made the idea of climbing them in one day a popular challenge walk known as the Yorkshire three peaks.
Another southerly dale is Wharfedale within which Kettlewell is a popular place to start walks. Here the hills take the form of large stretches of moorland bounding the dales. However many limestone features can be found in the lower land in the dale, most famously including Kilsney crag.
As you go further north within the dales into the valleys of Wensleydale and Swaledale the influence of the limestone is reduced and the hills are large sprawls of wild moorland bounding the valleys.
Indeed by the time Swaledale (the most northerly of the Yorkshire dales) is reached the main interest lies in the valley and it's the hill sides immediately bounding it surrounds than the nearby hill tops, one of which Rogans Seat has been termed the least interesting 2000ft hill in England.
Even within these dales the influence of the limestone is very noticable in the form of hillside scars, waterfalls within the valleys. The final important contribution made by the limestone is that the dales themselves are rich, green grassland giving the whole area a much more welcoming feel than the Dark peak.
An interesting exception to the general character of the dales can seen within the westerly dale of Dentdale. Here Calf Top and in particular the Howgill Fells rising above Sedbergh arguably have more in common with the gentler parts of the Lake District than the Yorkshire dales.
This is less of a surprise when you consider that at this point the hills connecting the two national parks are broken only by a thin valley cut by the river Lune.
