n Mean (°) Median (°) Weighted means of dunes 5785 19.8 19.8 Dunes 855 17.8 15.0 Sandstones 5242 19.8 19.9 Table 3. A summary of the overall results when measuring dip angles of modern sand dunes and ancient sandstones. Fig. 7. A comparison of 855 dip measurements from modern dunes, and 5,242 dip measurements from individual sandstone cross-beds plotted as a histogram. Note the bimodal curve of the eolian dunes and the bell-shaped curve of the sandstones. Box plots of the data are plotted below the histogram. The greater spread of the eolian data are indicated by the greater standard deviation of the data (10.1) compared to the narrower distribution of the dune data and a smaller standard deviation (5.7). Most have focused on the larger number of high-angle cross-bed dips in eolian settings but note the even greater number of low-angle cross-bed inclinations. Sandstones are “compacted,” while eolian dunes typically have porosities of about 40%. Some authors have suggested the sandstone data can be produced by “compacting” the eolian data by about 24% (see Fig. 10). WHITMORE Cross-bed inclinations 2023 ICC 603
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