Comparison of three grain size measuring methods applied to coarse-grained gravel deposits

Garefalakis, Philippos; do Prado, Ariel Henrique; Mair, David; Douillet, Guilhem Amin; Nyffenegger, Franziska; Schlunegger, Fritz (2023). Comparison of three grain size measuring methods applied to coarse-grained gravel deposits. Sedimentary geology, 446, p. 106340. Elsevier 10.1016/j.sedgeo.2023.106340

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The size of grains in gravel and conglomerate deposits is most easily measured on photos taken from related outcrops. However, the occlusion of grains by the sedimentary matrix or other grains, and possible distortions of photos, could introduce a bias in such datasets. Here, we explore the uncertainties associated with datasets where the lengths of the grainswere measured on photos. To this end, we analysed coarse-grained (>2mm) fluvial material from a gravel pit (Bern, Switzerland). We compared grain size data collected from digital photos with the results where the same material was measured with a calliper and mechanically sieved. Our analyses reveal that the percentile values such as the D16, D50 and D84 of datasets where the grains' longest visible axes were measured on digital photos best correlate to the corresponding percentile values of data collected through sieving. We also find that the longest visible axes of grains measured on digital photos are c. 17 %
smaller than the lengths of the intermediate b-axes of grains measured with a calliper. We therefore suggest to measure the longest visible axes on digital photos, and to correct the data by a corresponding factor such as +17 % for the target grain size percentiles.

Item Type:

Journal Article (Original Article)


08 Faculty of Science > Institute of Geological Sciences
08 Faculty of Science > Institute of Geological Sciences > Exogenous Geology

UniBE Contributor:

Garefalakis, Philippos Erich, do Prado, Ariel Henrique, Mair, David, Douillet, Guilhem Amin, Nyffenegger, Franziska, Schlunegger, Fritz


500 Science > 550 Earth sciences & geology








Fritz Schlunegger

Date Deposited:

02 Mar 2023 10:31

Last Modified:

05 Mar 2023 02:19

Publisher DOI:





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