A Case Against Pelagochthony: The Untenability of Carboniferous Arborescent Lycopod-dominated Floating Peat Mats

Abstract

In order to rectify perceived problems in the nineteenth century autochthonous and allochthonous theories of coal formation, an alternative theory was proposed that hypothesized that sylvo-marine, lycopod-dominated, floating peat mats were responsible for the development of Carboniferous coals. This pelagochthony theory was not widely accepted at the time but recently has been resurrected in order to explain the formation of Carboniferous coals well within the “Biblical time scale.” Numerous, unsubstantiated “facts” have been proposed to support the floating mat hypothesis including: the supposed hollow construction of arborescent lycopods; the extensive intertwining of stigmarian axial systems; a supposed continuous transgression of the shallow epeiric sea; a supposed stratified water column below the floating mat; and others. An examination of lycopod anatomy and morphology negates the contention of hollow arborescent lycopods and allows establishment of criteria to aid in the identification of in situ plants. An evaluation of the floating mat hypothesis in perspective demonstrates the untenable character of this proposed coal-forming mechanism. Reattachment of the floating mat is highly probable in the shallow epeiric sea, either by stigmarian axial systems proper, or helically arranged ‘rootlets.’ Isostatic adjustments of the mat would continue downwards as more biomass is generated by maturation of the trees. However, if this is ignored, meteoric waters introduced onto the surface of the mat would promote rapid decay in the tropical environment, and may preclude peat accumulation.