The term applied to a group of sedimentary structures found on the base of beds. Sole structures are mostly formed by the scouring action of a current, or by the passage of an implement (tool) over a muddy substrate, followed by the infilling of the scour by sands (scour and fill). Sole structures include flute marks, produced by turbulent flows of water; skip, prod, bounce, drag, and groove marks, caused by the transport of an object over the mud; and load casts, formed by the sinking of dense sand into underlying layers of less dense mud. Sole structures provide an important means of determining the ‘way-up’ of beds, and in many cases give an important indication of palaeocurrent direction. See palaeocurrent analysis.
Subjects: Earth Sciences and Geography.