Schmidt Hammer exposure dating (SHED): Calibration boulder of Tomkins et al. (2016)

Jason Dortch, Philip Hughes, Matthew Tomkins

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For the Quaternary community to test and utilize the SHED curves presented in Tomkins et al. (2016) and to develop their own calibration curves, SHED R Values need be standardized. When applying SHED to undated surfaces, Schmidt hammer calibration should be undertaken on a surface with a known R Value by taking the average of 30 R Values without rejecting any values. This procedure should be used for all surfaces dated in a study and should be repeated after data collection to determine any change in Schmidt hammer functioning.

The best methods for robust calibration include:

1) The researcher calibrating a Schmidt hammer on the top surface of the University of Manchester calibration boulder (best method);

2) Mail your Schmidt hammer to the corresponding author who will send the data and Schmidt hammer back (note: this does not account for operator variance);

3) Locate one of the 98 boulder or bedrock surfaces reported in Tomkins et al. (2016) and use it as a calibration point. In this case the researcher must be confident that they are using the exact same boulder or bedrock surface from where the R Value was obtained by Tomkins et al. (2016, Table 2). Whilst this approach is feasible, we advocate caution since replicating the precise same surface may sometimes be difficult.

The University of Manchester calibration boulder is a 1.8 m-long × 0.7 m-wide × 0.7 m-high block of Doddington Sandstone ≥340 Ma that was quarried at Doddington Hill, near Wooler in NE England, and transported to the University of Manchester c. 30 years ago (John Nudds The boulder is located at 53°27′60.0″N, 2°14′05.9″W on Bridgeford Street between the Arthur Lewis Building (# 36 on campus map) and Waterloo Place (#38) in a rock garden and engraved as #11 (Fig. 1). The boulder is a white sandstone that is now buff to tan coloured due to urban pollution and has red streaks due to iron staining. Cross-stratification is visible on both the weathered and cut surfaces.
Original languageEnglish
Number of pages2
JournalQuaternary Geochronology
Publication statusPublished - 7 Jun 2016


  • Schmidt Hammer


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