Comparison of electronic and mechanical Schmidt hammers in the context of exposure‐age dating: are Q‐ and R‐values interconvertible?. Issue 8 (5th May 2014)

• Record Type: Journal Article
• Authors: Winkler, Stefan; Matthews, John A.
• Is Part Of: Earth surface processes and landforms. Volume 39:Issue 8(2014)
• Page Start: 1128
• Page End: 1136
• Publication Date: 2014-05-05
• Subjects: Geomorphology -- Periodicals; 551.4
• DOI: 10.1002/esp.3584
• Languages: English
• ISSNs: 0197-9337

Abstract

<abstract abstract-type="main"> <title>ABSTRACT</title> <p>Application of Schmidt‐hammer exposure‐age dating (SHD) to landforms has substantially increased in recent years. The original mechanical Schmidt hammer records <italic>R</italic>‐(rebound) values. Although the newly introduced electronic Schmidt hammer (SilverSchmidt) facilitates greatly improved data processing, it measures surface hardness differently, recording <italic>Q</italic>‐(velocity) values that are not <italic>a priori</italic> interconvertible with <italic>R</italic>‐values. This study is the first to compare the performance of both instruments in the context of field‐based exposure‐age dating with a particular focus on the interconvertibility of <italic>R</italic>‐values and <italic>Q</italic>‐values. The study was conducted on glacially polished pyroxene‐granulite gneiss, Jotunheimen, southern Norway. Results indicate that mean <italic>Q</italic>‐values are consistently 8–10 units higher than mean <italic>R</italic>‐values over the range of values normally encountered in the application of SHD to glacial and periglacial landforms. A convenient conversion factor of ±10 units may, therefore, be appropriate for all but the softest rock types close to the technical resolution of the instruments. The electronic Schmidt hammer should therefore be regarded as a useful complement and potential replacement for the mechanical Schmidt hammer. Conversion of published <italic>R</italic>‐values data to <italic>Q</italic>‐values requires, however, careful control and documentation of instrument calibration. Copyright © 2014 John Wiley & Sons, Ltd.</p> </abstract>