R.W. Stanton Thomas A. Ryer Sharon S. Crowley 1989 <p><span>Volcanic ash which fell in the peat swamp that formed the Upper Cretaceous C coal bed (Ferron Sandstone Member of the Mancos Shale, Utah) produced semi-impermeable layers that caused the ponding of surface waters. Coal samples from directly above tonsteins (altered volcanic ash partings) are enriched in desmocollinite, telinite, and detrocollinite, as a result of poorly drained swamp conditions; coal samples from directly below tonsteins are enriched in semifusinite, inertodetrinite, and fusinite, as a result of well-drained conditions. Leaching of the volcanic ash or the incorporation of volcanic ash in peat provided a source for many elements (including Zr, Nb, Th, and Ce) that are enriched in coal samples taken from directly above and below tonsteins.</span></p> application/pdf 10.1016/0146-6380(89)90059-4 en Elsevier The effects of volcanic ash on the maceral and chemical composition of the C coal bed, Emery Coal Field, Utah article