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Keywords:

  • Schmidt Hammer;
  • relative dating;
  • cosmogenic ages;
  • absolute dating

Abstract

The Schmidt Hammer (SH) method is used to quantify the rock weathering degree and has been proposed as a relative dating tool. Terrestrial Cosmogenic Nuclide (TCN) methods provide absolute exposure ages for erosive surfaces. Few works combine both methods for surfaces older than the Holocene. We compare data obtained by both methods for c. 150 ka bp glacial and fluvial erosive granite surfaces from northwest Spain. Rebound values (R) have been firstly compared with the rock density to assess the correlation with the rock strength, independently from influence of factors such as wetness and roughness in the R-values. For erosive glacial surfaces older than 100 ka R-values are confined in a narrow range, with no differences within errors. Stepped fluvial surfaces of 700 m to 70 m above present sea level show an inverse correspondence between TCN ages and R-values, although no age predictions can be done on the basis of the R-values. Thus, age inferences exclusively based on R-values may not be realistic, but SH studies could be a useful tool for selecting surfaces for TCN dating. Copyright © 2009 John Wiley & Sons, Ltd.