The micro‐erosion meter: Use and limitations

Abstract

Detection of anomalies in measurements of low rates of limestone surface lowering with a traversing micro-erosion meter (MEM) led to temperaturecontrolled laboratory and field investigations of some sources of error in the method. Regressions for the correction of temperature change in the instrument and in the stud-rock interface were obtained. Probe erosion tests permitted a correction to be devised and also provided information whereby a measure of operational irregularity was adopted. Corrections and error terms were applied to field measurements from two southern New South Wales karsts and a collection of Australian limestone slabs exposed at one site.Examination of these results and of published MEM rates from other parts of the world validated the MEM method. Marine platforms are lowered at such gross rates that these error sources may be neglected there. However limestone lowering in terrestrial environments cannot be assumed to proceed at rates which permit this and recommendations are made about procedures to ensure that investigations are prosecuted within the limitations of the method.

Desenvolvimento de um microerosómetro do tipo TMEM para aplicação em plataformas rochosas litorais

“…Efectivamente, estudos de laboratório efectuados por SPATE et al (1985) concluem que variações de temperatura do ar entre 4º e 25ºC originaram diferenças de 0,006 mm nos valores obtidos pelo MEM utilizado. Embora os autores considerem esta ordem de erro pouco significativa no cálculo de rebaixamento das plataformas rochosas litorais, na investigação em curso pretende-se efectuar todas as medições em condições de temperatura semelhantes, procedimento que já foi seguido nas campanhas efectuadas.…”

“…Outros pormenores de instalação, bem como procedimentos mais especí-ficos podem ser consultados em HIGH e HANNA (1970), TRUDGILL et al (1981), SPATE et al (1985), ROBINSON (1976), STEPHENSON e KIRK (1996) e STEPHENSON (2000.…”

Determining timescales of natural carbonation of peridotite in the Samail Ophiolite, Sultanate of Oman

“…Travertine erosion rates could be determined by employing a microerosion meter (e.g. High and Hanna, 1970;Spate et al, 1985;Cucchi et al, 2006) or through measuring cosmogenic nuclides such as 36 C1 (e.g. Dockhurn et al, 1991; Stone et al, 1996Stone et al, , 1998, 10Be (e.g.…”

Downwearing rates on shore platforms of different calcareous lithotypes

“…The initial set of micro-topography measurements (255 points inside each TMEM triangular section) was performed monthly between September and December 2008 and, after this initial set, measurements were performed bimonthly until September 2009. The monthly and bimonthly measurements were performed in order to observe if seasonal differences occurred due to environmental variables such as temperature as observed by Spate et al (1985) in laboratory experience. As opposed to the findings of Stephenson and Kirk (1998), no seasonal differences were observed, probably because temperature range between measurements was not high enough and this parameter does not significantly affect the surface lowering rate in some rocky shore platforms (Spate et al, 1985).…”

“…The monthly and bimonthly measurements were performed in order to observe if seasonal differences occurred due to environmental variables such as temperature as observed by Spate et al (1985) in laboratory experience. As opposed to the findings of Stephenson and Kirk (1998), no seasonal differences were observed, probably because temperature range between measurements was not high enough and this parameter does not significantly affect the surface lowering rate in some rocky shore platforms (Spate et al, 1985). The supporting screws directly and permanently bolted into the rock during the1 year of measurements, as well as the careful handling of the comparator, avoided surface damage by successive measurements.…”