Figure B2
Definition and interpretation of ball-and-pillow structure.
For simplicity, stratification is not shown in the lower, less dense layer. (A) Definition diagram for ball-and-pillow structure, where a, b and c are distinct sedimentation units. (B) Ball-and-pillow structure from an Upper Carboniferous delta front sequence at Amroth, west Wales, UK. Arrows point to individual pseudonodules. The section illustrated is 3 m thick. (C) Formation by repeated detachment from the base of a layer undergoing load deformation. (D) Formation by the simultaneous loading of several couplets of denser and less dense sediment. (E) Formation by a process of sedimentary stoping in which mobile sediment rises through an essentially passive layer.