Much of the Yorkshire Dales area is "limestone country", the geology of which gives rise to the area's spectacular natural and unique karstic features, including limestone cliffs (such as Malham Cove) and limestone gorges (such as Gordale Scar), as well as some of the finest examples of limestone pavements in Europe.
Different types of carboniferous limestone occuring in the dales include the distinctively white or whitish grey Great Scar Limestone, the generally darker limestone strata (known as "cyclothems") of the Yoredale Series (the layered structure of which gives rise to fine waterfalls such as Hardraw Force and Aysgarth Falls in Wensleydale etc.), and the relatively fossil rich reef limestone which is found in reef knolls such as those at Scosthrop Moor and the Cracoe Reef Knolls. Magnesian limestone (a late Permian dolomitic rock) can also be found near Ripon and at Knaresborough at the very eastern edges of the Yorkshire Dales area.
Because this is limestone country there are many caves and potholes in the area, and the Yorkshire Dales is one of the country's most important regions for caving and potholing. Whilst many of the largest cave systems are found in the Great Scar facies, there are also significant systems in the limestone cyclothems of the Yoredale Series, and caves also occur in the reef knolls and even the smaller areas of (arguably less karstic) Magnesian limestone which is found to the east.
The presence of limestone and other kinds of surface rock in the dales has led to a range of large scale industrial quarrying operations which cause permanent and irreversible damage to the landscape - but which are still permitted to take place even within the boundaries of the national park.
- Walks in Limestone Country by Alfred Wainwright