5.3 PRIMARY INORGANIC SEDIMENTARY STRUCTURES
147
Fig. 5.14. Basic nomenclature of cross-bedding. Tabular planar cross-beds have subplanar foresets. Trough
cross-beds have spoon-shaped foresets. Isolated cross-beds are referred to as sets. Vertically grouped foresets constitute a coset.
ficatory schemes (e.g., Allen, 1963). Basically, two main types of cross-bedding can be
defined by the geometry of the foresets and their bounding surfaces: tabular planar
cross-bedding and trough cross-bedding (McKee and Weir, 1953). In tabular planar
cross-bedding, planar foresets are bounded above and below by subparallel subhorizontal set boundaries (Fig. 5.15). In trough cross-bedding, upward concave foresets lie
Fig. 5.15. Tabular planar cross-bedding in fluvial Cambro-Ordovician sandstones, Jebel Gehennah, southern
Libya.
147
Fig. 5.14. Basic nomenclature of cross-bedding. Tabular planar cross-beds have subplanar foresets. Trough
cross-beds have spoon-shaped foresets. Isolated cross-beds are referred to as sets. Vertically grouped foresets constitute a coset.
ficatory schemes (e.g., Allen, 1963). Basically, two main types of cross-bedding can be
defined by the geometry of the foresets and their bounding surfaces: tabular planar
cross-bedding and trough cross-bedding (McKee and Weir, 1953). In tabular planar
cross-bedding, planar foresets are bounded above and below by subparallel subhorizontal set boundaries (Fig. 5.15). In trough cross-bedding, upward concave foresets lie
Fig. 5.15. Tabular planar cross-bedding in fluvial Cambro-Ordovician sandstones, Jebel Gehennah, southern
Libya.