Incision, Instability and isolation- attempting to constrain cave development in the most easterly of the Yorkshire Dales, northern England, UK

The karst of the Yorkshire Dales, situated in the Pennine hills of northern England, provides an under realised opportunity for paleo climate studies in mid latitudes. It was marginal to the Last Glacial Maximum British and Irish Ice Sheet.

The valley is surrounded by extensive moorland underlain by sandstone and mudstone dominated Millstone Grit Group strata. Underlying the Millstone Grit are strata of the cyclothemic Yoredale Group which include cavernous limestone units. The incision of the Upper Nidderdale valley has partially removed the clastic cover revealing limestone beds within the Yordale succession in three valley floor inliers.

By far the most extensive cave system is that beneath the main valley where the River Nidd in normal conditions sinks into the Limley inlier through impenetrable fissures upstream of Manchester Hole. The underground river from Manchester Hole flows into Goyden Pot, then onto New Goyden Pot to finally resurges at Nidd heads Risings forming a combined system with over 9 km of passages. The main stream passage and main chamber of Goyden Pot are floored by fallen blocks indicating collapse has played a major part in cave development. Some of the blocks consist entirely of speleothem and many show evidence of re-dissolution including incision and the development of scalloped surfaces cutting across the original depositional structure.

U-series dating of speleothem from the Goyden Pot cave system has shown that the incision of the upper reaches of the Nidd valley must have exposed the limestone strata of the Limley, Thrope and Lofthouse inliers prior to the Last Glacial Maximum and cave development was well underway by early MIS 3. The nature of the samples so far dated show the presence of significant detrital thorium seriously limiting the precision of the work.

The Canal Cave system is located in the Lofthouse inlier and consists of a narrow east-west orientated passage containing a 5 m climb with the upstream (western) end blocked by calcite. Down cutting of the River Nidd has intersected the route of the passage, thus draining the cave, which can be traced across the riverbed as a slot leading to the downstream continuation under the east bank. The sample was again contaminated by detrital thorium resulting in a considerable loss of precision as has been found elsewhere in the valley however a late Pleistocene date is indicated for the basal part of the sample (14136 +11.7 - 11.3 ka BP). This shows the cave was drained and thus valley of the River Nidd at Lofthouse had incised close to its present level by the very latest late Pleistocene.