20 The American Geologist. July, i896 
the process of anthracitificatioii. Prof. A. H. (ireen has re- 
marked that coal often becomes much more carbonized when 
its roof changes from a shale or chiyey one to sandstone, a 
statement the author endorses from personal observation in 
coal mines, though of course there are exceptions. The author 
would submit that the reason why some benches of anthracite 
seams are locall}- more carbonized than others* is because the 
different benches were originally or subsequently not all 
equally water-soaked or similarly acted upon by the hydro- 
dynamic influences to which they were differentially sub- 
jected. He also submits that the included water of the Coal 
Measures, when under thermal pressure, would be forcibly 
injected or diffused among and through the organic as well 
as the inorganic constituents of the strata to such a degree as 
would bring its action within layers or beds, under ordinary 
conditions, largely excluding it. And in regard to thrust-pres- 
sure, it is not likely that the pressures that were concerned in 
the folding, crushing and faulting of the anthracite Coal Meas- 
ures were sufficient to create heat enough to still further 
anthracitize anthracite to an appreciable extent, assertions to 
the contrary by men of note notwithstanding. To the jam- 
ming and squeezing of plication and fracturing most of the 
"slips," "faces," "backs," "cutters," "joints," etc., of miners 
may be attributed. 
In the author's paper entitled "Anthracite and Bituminous 
Coal Beds. An Attempt to throw some light upon the man- 
ner in which Anthracite was formed; or Contributions to- 
wards the Controversy regarding the Formation of Anthra- 
cite," read before the Geological Society of London, "iSth 
January. 1893, and from the discussion that followed it, it 
appeared tolerably clear that the association of arenaceous 
strata and anthracite was something more than (iccidentdL 
From a much wider range of observations I think we have 
now pretty thoroughly demonstrated this circumstance, thus 
showing that the almost world-wide proximity of the two 
materials is something more than a mere coincidence. And 
while I am prepared to believe that anthracite may have been 
produced by regional metamorphism in the absence of any 
considerable thickness of sandstones, etc., in some localities, 
*"Clas8iflcation and Composition of Pa. Anthracites.'" by C. A. Ash- 
burner. 188G, p. 19. 
