Online Calculator for Schmidt Hammer Exposure Dating:
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SHED Earth (

This repository comprises the source code for the website (based upon Django).

SHED refers to Schmidt Hammer Exposure Dating: a technique that provides a cost-effective solution for dating the exposure of granite surfaces. This can be used to constrain the timing of past events e.g. glacial retreat, which permits a better understanding of the links between climate and landscape evolution.

The approach is based upon a study by Tomkins et al. (2016), in which a statistically significant relationship was observed between the exposure ages (derived from terrestrial cosmogenic nuclide dating), and Schmidt Hammer rebound values (R-values) of 25 granitic surfaces from NW England and Scotland:

SHED Calibration Curve

These data indicate that granite can weather linearly over significant spatial scales for regions of similar climate and permits the estimation of exposure ages based upon the R-value recorded on the rock. The technique has been demonstrated to be of comparable accuracy and precision to ages derived from terrestrial cosmogenic nuclide dating, but without the significant expense that goes along with the use of such techniques, making it useful for researchers and students alike. This dataset has recently been updated with new exposure ages from the Holocene and Younger Dryas and is now applicable over the timescale 0.8 - 22.5 thousand years ago:


Tomkins, M. D., Dortch, J. M., & Hughes, P. D. (2016). Schmidt Hammer exposure dating (SHED): Establishment and implications for the retreat of the last British Ice Sheet. Quaternary Geochronology, 33, 46–60.