Erratic judgements: re‐evaluating solutional erosion rates of limestones using erratic‐pedestal sites, including Norber, Yorkshire

Abstract

The re-interpretation of surface karst landforms in Northern England has led to a reexamination of well-known erratic-pedestal sites that were the origin for karst denudation rates applied extensively, on the supposition that erratics protect underlying limestone from rainwater solution. Height of the pedestal has been used to calculate long-term solutional-lowering, as much as 50 cm in 15 ka (33.3 mm/ka) from UK sites. The sites include Norber and Scar Close, Yorkshire, UK. This paper shows that the sites have been misinterpreted, in particular at Norber where the erratics lie on a pre-existing structurally stepped surface. Norber and several other sites also experience much mechanical weathering, in relatively weak, well-fractured limestones, a process which must be distinguished from solution. Sites in strong, less-fractured limestones demonstrate lower rates, which are sounder indications of land surface lowering. Some pedestals have been confirmed as partly resulting from solutional weathering in surrounding soil and vegetation. Re-evaluation reduces solution rates to 3-13 cm in 15 ka. Applying such rates has profound implications for understanding limestone landscapes, challenging orthodox views.

In-situ cosmogenic 36Cl denudation rates of carbonates in Guizhou karst area

“…The 36 Cl-denudation rates in Guizhou are also comparable with other long-term estimates obtained by height changes of pedestals beneath glacial erratics on a pavement, i.e. Yorkshire, UK (3-13 mm ka −1 ) [19]; Maren Mountains, Switzerland (15 mm ka −1 ) [20]; West Irian, Indonesia (32 mm ka −1 ) [21]; Leitrim, Ireland (42 mm ka −1 ) [22] and Patagonia (40-75 mm ka −1 ) [23]. However, they are much lower than that from tsunami remains on raised coral-reef terraces in Kikaijima, Japan (205 mm ka −1 ) [24].…”

Controls on denudation rates in tectonically stable Mediterranean carbonate terrain

“…Chemical weathering and denudation rates of carbonate terrains are frequently measured over short time scales using spring dissolved load, micro-erosion meters, or weight loss measurements using standard tablets (Ford and Williams, 2007;Gabrovšek, 2009). Longer-term denudation rates of carbonate rocks are estimated by measuring the height of surface irregularities formed beneath noncarbonate cap rock such as silicate glacial erratics deposited on limestone (Goldie, 2005;Peterson, 1982;Wilson et al, 2012) or silicate veins, nodules, or dikes that stand out of carbonate surfaces as a result of differential erosion (e.g., Lauritzen , 1990). Terrestrial cosmo genic nuclides (TCN) have been applied to quantify denudation rates on local and drainage-basin scales at time scales of 10 3 -10 6 yr (von Blanckenburg, 2005).…”

Granular disintegration of marble in nature: A thermal-mechanical origin for a grus and corestone landscape

“…Royer-Carfagni, 1999;Siegesmund et al, 2000;Weiss et al, 2002;Zeisig et al, 2002;Malaga-Starzec et al, 2002;Koch and Siegesmund, 2004). With few exceptions (Smith, 1988;Goudie and Viles, 2000;Goldie, 2005;Viles 2005; Viles and Goudie, 2007), however, mechanical weathering in carbonate rock types has gone virtually unnoticed by geologists, geomorphologists and physical geographers despite the fact that engineers have long recognized that mechanical weathering of carbonates, particularly marble, can represent a significant portion of their degradation (e.g. Kessler, 1919;Rosenholtz and Smith, 1949).…”