Welcome to SHED Earth. 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, 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)1, 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. 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 29 additional exposure ages from across Scotland and Ireland2 and is now applicable over the timescale 0.8 - 23.8 thousand years ago, almost the entirety of British-Irish Ice Sheet retreat from its maximum extent.
This is the latest calibration curve for the British Isles and is based on 54 TCN dated surfaces from Scotland, NW England and Ireland. These exposure ages are calculated using the time-dependent Lm scaling scheme3,4, the Loch Lomond production rate 5 and assuming 0 mm ka-1 erosion. For full details, see Tomkins et al. (2017)2. It is anticipated that as new calibration curves are constructed in similar well-dated regions, they will be made available for use on this site.
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The source code for this website is available on GitHub.