Pustule dome

A pustule dome (or 'Zit') occurs when a more buoyant older sediment swells and rises through a harder constraining layer above. An excellent example of this feature can be observed on the South Kaibab Trail in Grand Canyon National Park. This feature was named by Dr Duncan McCollin of the University of Northampton in April 2007. Here a Permian evaporite deposit pushes up through limestone in the Toroweap Formation. The existence of this feature has recently been questioned by John Sinclair. In a 2008 discussion on the validity of Pustule Domes, Myles Davies, also of The University of Northampton, highlighted the increasing scepticism of this topic, contrasting the permeability of Limestone formation, alongside the butte which surround the South Kaibab Trail. (A Closer Look [2008] , Lectures in the Preface to the World of Geology, University of Northampton.)

A forthcoming journal article for South Western American Geology Studies, by respected Geographer Christopher Everard, states that Davies is overlooking some key concepts of Limestone formation, including Tresputarian existence.

This is a relatively new area of Geology with proposals for further study, to be put forth in the coming decade.