ABSTRACT

Dish structures, like convolute lamination over a decade ago, have been linked by geologists almost exclusively with flysch deposits, but, like convolute lamination, they are now being found in other settings. To previous reports of occurrences of dish structures in deltaic and alluvial deposits can be added their presence in the shallow marine Late Jurassic Canyon Springs Sandstone in the southern Black Hills, South Dakota. Proposed origin for dish structures from antidunes or grain flow in the upper flow regime are not compatible with associated structures in this occurrence. Instead, a recently proposed dewatering mechanism seems most consistent with available evidence. Fluid escape is especially clearly evidenced on a macroscopic scale in glacial lacustrine deposits near Appleton, Wisconsin. Pillar structures penetrating cross-laminated sands there suggest by analogy a larger-scale continuum with the more subtle disruptions that produced dishes.