Yol.  49.]  PROCEEDINGS  OF  THE  GEOLOGICAL  SOCIETV.  II 
2.  “  Anthracite  and  Bituminous  Coal-beds.  An  Attempt  to  throw 
some  light  upon  the  manner  in  which  Anthracite  was  formed  ;  or 
Contributions  towards  the  Controversy  regarding  the  .Formation  of 
Anthracite.”  By  W.  S.  Gfresley,  Esq.,  F.Gr.S. 
[Abstract.] 
The  Author  does  not  seek  to  advance  any  new  theory  in  this 
communication,  nor  to  proclaim  new  facts  of  any  importance,  but  to 
put  old  facts  in  something  of  a  new  light,  in  order  to  aid  the  inves¬ 
tigations  of  others.  His  main  object  is  to  establish  two  facts,  viz.: — 
that  the  associated  strata  of  anthracite-beds  are  more  arenaceous 
than  those  containing  so-called  bituminous  coal-beds,  and  that  the 
prevailing  colours  of  the  sandstones,  grits,  etc.,  of  anthracite  regions 
are  greyer  and  darker  than  those  of  regions  of  bituminous  coal.  To 
these  facts  may  perhaps  be  added  a  third,  that  the  more  anthracitic 
the  coal-beds,  and  the  more  siliceous  the  enclosing  strata,  the  harder 
and  tougher  these  associated  strata  are. 
While  recognizing  that  the  rocks  of  many  anthracite  regions  have 
undergone  great  disturbance,  he  cites  other  areas  where  coal-basins 
have  been  much  folded,  without  any  corresponding  production  of 
anthracite  in  considerable  quantity. 
The  modes  of  occurrence  of  anthracite  are  illustrated  by  many 
instances  observed  by  the  Author  in  the  Old  and  Hew  Worlds. 
Discussion. 
The  President  observed  that  the  apparently  greater  abundance 
of  anthracite  in  arenaceous  rocks  may  be  due  to  chemical  causes. 
Perhaps  the  gases  escaped  from  the  coal  through  these  porous 
strata,  whereas  they  were  ‘  bottled  up  ’  in  argillaceous  strata  and 
so  preserved  the  bituminous  character  of  the  coals. 
Prof.  Hull  remarked  that  the  question  whether  the  anthracitic 
condition  of  coal-seams  depended  on  the  predominance  of  sandstones 
amongst  the  associated  strata,  as  he  understood  the  Author  to 
suggest,  would  require  careful  observation  of  the  sections  of  par¬ 
ticular  coalfields,  but  was  one  which  deserved  attention.  If  we 
were  to  take,  for  example,  the  South  Wales  Coal-basin,  it  would  be 
interesting  to  ascertain  whether  sandstones  predominated  in  the 
western  parts  of  that  basin  where  anthracite  was  found,  and  shales 
in  the  eastern  parts  where  the  coal  was  bituminous.  This  might  be 
done  by  a  comparison  of  vertical  sections  of  the  strata,  and  if  found 
to  be  the  case,  the  argument  would  have  some  weight  that,  owing 
to  the  greater  porosity  of  the  sandstones  over  the  shales,  the  escape 
of  the  gaseous  products  had  been  easier  where  these  were  in  excess 
than  where  the  less  porous  shales  predominated.  But  this  would 
not  wholly  account  for  the  production  of  anthracite,  which  probably 
depended  for  its  origin  on  a  variety  of  conditions. 
The  following  specimens  were  exhibited  : — 
Bock-specimens  exhibited  by  Prof.  J.  W.  Judd,  F.B.S.,  Y.P.G.S., 
in  illustration  of  his  paper. 
b2 
