Measurement and calibration of weathering using the schmidt hammer, on wave washed moraines on the upper norrland coast, Sweden

Abstract

The Schmidt hammer has for some years been used to measure the hardness of different rock surfaces and to date relatively boulders in moraine deposits. In this paper applications on isostatically raised boulder-beaches and rocky shores are described. The research area is the northern Swedish Bothnian coast where present isostatic uplift is between 08-1.0cm year-'. Elevations above sea-level can be converted to a timescale. Rebound values (R) of the Schmidt hammer are correlated with the altitude and the degree of rock weathering can be estimated for each site.Eight sites with boulder-beaches and nine sites with rocky shores have been analysed. For boulder-beaches correlation-coefficients of 0.82-0.97 for weathering values (R) and the elevations above sea-level were obtained. For the rocky shores these values were calculated to 0.75497.This method has applications in both geomorphology and archaeology. For example, a deep layer of weathered dolerite in the Nordingrl region, which previously has been regarded as a post-Weichselian formation, can be shown to be of pre-Weichselian origin. Several archaeological applications are also mentioned in the paper.

The effect of rock moisture on Schmidt hammer rebound: tests on rock samples from Marion Island and South Africa

“…When measuring rebound in the field, Sjöberg and Broadbent (1991) note that intact blocks or boulders should be sufficiently large and placed in a stable position such that hammer impact energy is returned to the hammer. However, no specific minimum rock mass is suggested in the study, or in other investigations using the hammer.…”

“…Matthews and Shakesby, 1984;McCarroll, 1989a, b;Boelhouwers et al, 1999;Sumner et al, in press) and in spatial comparisons of the degree of weathering (e.g. Ballantyne et al, 1990;Nyberg, 1991;Sjöberg and Broadbent, 1991;Hall, 1993;Meiklejohn, 1994).…”

The use of the Schmidt Hammer and Equotip for rock hardness assessment in geomorphology and heritage science: a comparative analysis

“…For example, there is considerable controversy about the relationship between rock weathering and time, and whether rates are linear or nonlinear. Sjöberg and Broadbent (1991) were able to obtain a measure of how weathering developed through time by examining the Schmidt Hammer values of raised beaches at different elevations in Sweden. Spatial variations in hardness can also be used to investigate environmental infl uences on weathering, such as aspect (Hall, 1993;Waragai, 1999;Burnett et al, 2008) and seasonal snow patches (Ballantyne et al, 1989(Ballantyne et al, , 1990Benedict 1993: Grab et al, 2005.…”

A correlation between Schmidt hammer rebound numbers with impact strength index, slake durability index and P-wave velocity

“…Various researchers (Osborn 1959;Krishnamurthy and Udas 1981;McCarrol 1991;Sjoberg and Broadbent 1991) have correlated the Schmidt hammer rebound numbers with degree of weathering of rocks including igneous rocks like gabbro, granite. Miller (1965) produced a general and crude correlation chart for Schmidt hammer, relating rock density, compressive strength and rebound number, applicable to all rock types.…”