Science, Maths & Technology
Practising science: Reading the rocks and ecology
...system of parallel ridges, or ripple marks, like the ones shown in Figure 13a, form by the action that flowing water has on the erosion, transport and deposition of sand grains. In sedimentary strata, ripples and dunes (which are effectively larger versions of ripple marks) are normally seen in cross-section rather than in plan view, because pristine depositional surfaces...