Editing River Wharfe (section)

==Geology==

Upper Wharfedale is an area whose rocks date from the [[Mississippian (geology)|Early Carboniferous]] period and lies north-west of [[Burnsall]]. Its main features are the Great Scar Limestone which forms a base to the overlying Yoredale Beds, a {{convert|300|m|adj=on}} deep strata of hard [[limestones]], [[sandstones]] and [[shale]]. These have been slightly tilted, toward the east. To the south-east of the area is the [[Millstone Grit]] laid down in the [[Pennsylvanian (geology)|Late Carboniferous]] period, and covered by heather moorland, hard crags and tors.<ref>{{cite web| url= http://www.yorkshiredales.org.uk/nationalparkauthority/policiesandstrategies/nationalparkpolicies/landscapecharacterassessment/31_langstrothdale-2.pdf|title=Langstrothdale Landscape Character Assessment| website= yorkshiredales.org.uk |publisher=Yorkshire Dales National Park Authority|year=2013|access-date= 25 March 2013|url-status=dead |archive-url= https://web.archive.org/web/20120905030422/http://www.yorkshiredales.org.uk/nationalparkauthority/policiesandstrategies/nationalparkpolicies/landscapecharacterassessment/31_langstrothdale-2.pdf|archive-date=5 September 2012}}</ref><ref name="Wharfe-Litton">{{cite web |url= http://www.yorkshiredales.org.uk/nationalparkauthority/policiesandstrategies/nationalparkpolicies/landscapecharacterassessment/32_upper_wharfedale_and_littondale-2.pdf| title= Upper Wharfedale & Littondale Landscape Character Assessment| website= yorkshiredales.org.uk |publisher=Yorkshire Dales National Park Authority|year=2013|access-date=25 March 2013| url-status= dead| archive-url= https://web.archive.org/web/20120905030258/http://www.yorkshiredales.org.uk/nationalparkauthority/policiesandstrategies/nationalparkpolicies/landscapecharacterassessment/32_upper_wharfedale_and_littondale-2.pdf|archive-date=5 September 2012}}</ref>

Weathering of the Yoredale Beds has produced a stepped profile to the valley sides, consisting of a shelf of limestone, sometimes grassy but often displaying such [[karst]] features as [[limestone pavement]], gorges and [[sinkholes]]. During the last ice age, the local ice cap at the head of the Dales fed glaciers to produce the classic U-shaped profiles seen today.<ref>{{cite web| url= http://www.yorkshiredales.org.uk/nationalparkauthority/policiesandstrategies/nationalparkpolicies/landscapecharacterassessment/33_wharfedale_craven_fault_area-2.pdf|title=Craven Fault| website= yorkshiredales.org.uk |publisher= Yorkshire Dales National Park Authority| year=2013|access-date=25 March 2013| url-status= dead| archive-url= https://web.archive.org/web/20120905030305/http://www.yorkshiredales.org.uk/nationalparkauthority/policiesandstrategies/nationalparkpolicies/landscapecharacterassessment/33_wharfedale_craven_fault_area-2.pdf|archive-date=5 September 2012}}</ref>

Where the river valley changes course into Lower Wharfedale, the change of underlying rock can be seen in the darker stone in the field walls. The Millstone Grit outcrops at the Cow and Calf Rocks near Ilkley form a rolling dissected plateau. Due to the impermeable nature of the rock, [[blanket bog]]s and mires form, and drier areas have wet and dry heaths and acid grasslands.<ref>{{cite web| url= http://www.yorkshiredales.org.uk/nationalparkauthority/policiesandstrategies/nationalparkpolicies/landscapecharacterassessment/34_mid_wharfedale-2.pdf| title= Mid Wharfedale Landscape Character Assessment |website= yorkshiredales.org.uk | publisher=Yorkshire Dales National Park Authority|year=2013|access-date= 25 March 2013| url-status=dead |archive-url= https://web.archive.org/web/20120905030303/http://www.yorkshiredales.org.uk/nationalparkauthority/policiesandstrategies/nationalparkpolicies/landscapecharacterassessment/34_mid_wharfedale-2.pdf| archive-date=5 September 2012}}</ref>

Coarse sandstones in the area are known as Addingham Edge and Bramhope Grits. The Otley Shell Beds become exposed at Otley Chevin. At Great Dib Wood the Otley Shell Bed is sandwiched between two [[Namurian]] sandstones.

Glacial lakes once filled Lower Wharfedale in which were deposited sand and gravel. These deposits were extracted and now form the basis of the Otley Wetland Reserve, and [[Ben Rhydding]] and Knotford Nook gravel pits.<ref>{{cite web| url= http://www.wharfequest.co.uk/geology_landscape.htm| title= Geology| website= wharfequest.co.uk| access-date=25 March 2013| url-status= dead| archive-url= https://web.archive.org/web/20130618193159/http://www.wharfequest.co.uk/geology_landscape.htm|archive-date=18 June 2013}}</ref>