Scallop measurement in a 10m-high vadose canyon in pool sink, ease gill cave system, yorkshire dales, uk and a hypothetical post-deglacial canyon entrenchment timescale


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August 2014


Understanding the vadose entrenchment of cave passages and relating this to the evolution of the external environment and climate has been little studied in the past. This report proposes a new technique to combine measurements of the lengths of wall scallops and their adjacent passage widths to determine the history of palaeo peak water velocity and volumetric flow rate in a vadose canyon. The study site is at an active 10m-high canyon in the Pool Sink section of the Ease Gill Cave System in the Yorkshire Dales, UK. This exhibits wall scallops continuously from its roof to its floor. The Sauter mean scallop lengths vary from 0.85 to 4.81cm and the canyon widths vary from 35 to 132cm. These enable water velocities at scallop dominant discharge to be calculated as varying from 76 to 548cm/sec. Peak flow rates are estimated to vary from 104 to 3581 litres/sec. Assuming a continuous entrenchment after the local Devensian deglaciation 18,000 years ago, this gives a mean floor lowering rate of 0.55mm per year. This seems reasonable, if both chemical and mechanical erosion applied. Based on this initiation hypothesis and assuming a constant entrenchment rate through time, the peak flow rates can be correlated roughly with known climatic changes during the Lateglacial and the Holocene. Studies of more sites in the Yorkshire Dales are required to ascertain whether such estimates of peak recharges could provide reliable proxies for major climatic events.


Scalloping, Ease Gill Cave System, Cave, Canyon, Karst, Scallop Measurement

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Cave and Karst Science, Vol. 41, no. 2 (2014-08-01).