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Compression and hardening over long periods of time, the processes by which coal is formed from plant materials.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


the compression, over time, of plant matter into coal
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˌkoʊ lə fɪˈkeɪ ʃən)

the conversion of plant material into coal by natural processes, as by diagenesis and, in some instances, metamorphism.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
References in periodicals archive ?
The bands observed at 1800-1000 [cm.sup.-1] were presumed to be associated with oxygenated C=O and C-O-R structures as the range was reported to reflect the presence of moieties of different C=O (amide, esters, carboxylic acids, quinines, etc.) and C-O-R (aryl and alkyl esters, carboxylic) structures depending on the extent of coalification [42].
As the anthracite coal undergoes high temperature or magmatic erosion during the coalification process, it can resist high temperature and has a higher tensile strength.
V Lopatin, "Temperature and geologic time as factors in coalification," Izvestia Akademii Nauk USSR, Seriya Geologicheskaya, vol.
In this section, based on a comparison between isosteric heat of adsorption calculated from adsorption isotherms and that obtained from calorimetric heat, we mainly focus on how the coalification and maceral compositions of coal affect the adsorption heat of coal for methane.
Cleats are linear discontinuities in coal forming a structural fabric in coal cleats are produced as a result ofphysical changes and tectonic stress during coalification.
This permeability may be influenced by the seepage pores and degree of coalification (Yao et al., 2009b; Meng and Li, 2013).
Paleogeothermal conditions in the illinois basin during late paleozoic coalification. Ph.D Thesis, Universidad de Illinois Urbana-Champaign, Illinois, USA.
It was also utilized to determine the degree of coalification by measuring the percentage of reflectance in reflected light (Valentim et al., 2006).
Tectonostratigraphic relationships and coalification trends in the Narragansett and Norfolk basins, New England.
The organic carbon content of coal increases gradually with increasing coalification degree.