304  LrEET.-GEN.  C.  A.  AlfMAHON - NOTES  ON  EAETMOOE.  [Aug.  1893? 
set  up  by  dynamic  agencies  after  the  consolidation  of  the  granite. 
There  is" not  a  trace  of  parallelism  of  structure  or  of  strain-shadows, 
and  lines  of  liquid  inclusions  in  the  quartz  have  no  connexion  with 
those  in  neighbouring  grains.  _  The  neighbouring  porphyritic  granite 
gives  evidence  of  similar  conditions,  and  exhibits  similar  phenomena, 
but  they  are  not  so  prominent  as  in  the  marginal  fine-grained  rock. 
I  now  propose  to  consider  briefly,  in  conclusion,  the  curious 
parallel  jointing  in  the  granite,  which  has  been  noted  by  almost  all 
previous  observers.  This  simulates  bedding  in  a  very  curious  wat , 
and  at  once  strikes  the  eye  of  the  geologist.  De  la  Beche  regarded 
this  as  a  44  thick  laminated  structure  pervading  the  masses  on  the 
large  scale,  probablv  agreeing  in  form  with  that  of  their  original 
surfaces  after  protrusion'  (Report,  etc.  p.  163).  The  explanation 
here  suggested  appears  to  have  satisfied  all  subsequent  wi iters  on 
the  granite  of  Dartmoor.  To  me  it  appears  very  unsatisfactory.  _  I 
cannot  suppose  that  the  Dartmoor  Granite  did  not  rise  be\ond  its 
present  level;  or,  if  it  did,  that  the  mammiform  contour  of  its 
present  surface,  obviously  due  to  subaerial  agencies,  represents  the 
original  contour  of  its  surface.  In  all  probability  the  granite  was 
continued  upwards,  and  the  present  contour  of  its  rugged  tors  and 
rounded  hills  has  no  relation  to  the  original  outline  of  the  intrusive 
mass.  However  this  may  be,  it  seems  certain  that  subaerial  agents 
have  cut  up  the  44  original  surfaces  after  protrusion  beyond  recog¬ 
nition.  How,  the  first  thing  to  strike  me  was  that  the  pseudo¬ 
bedding  of  the  granite  conforms  closely  to  the  present  slope  of'  the 
surface  of  the  hills,  and  this  was  confirmed  by  all  my  subsequent 
observations.  When  the  outcrop  occurs  on  the  apex  of  a  hill  its 
pseudo-bedding  is  horizontal.  When  it  occurs  on  the  eastern  side 
of  the  hill,  it  dips  eastward  at  an  angle  that  corresponds  to  the 
slope  of  the  hill.  On  the  northern  side  it  dips  northward  ;  on  the 
west,  westward;  and  so  on  all  round.  Unless  we  are  to  suppose 
that  the  contour  of  the  existing  hills  is  an  original  structure,  and  that 
the  very  abundant  rain  that  falls  on  Dartmoor  has  done  nothing  to 
carve  out  a  new  contour,  it  seems  obvious  that  the  pseudo-bedding 
must  be  a  structure  connected  with  subaerial  agencies. 
Some  students  of  the  Bible  have  been  puzzled  to  understand  what 
the  Prophet  meant  when  he  said  : — 44  Is  not  my  word  like  as  fire  ? 
saith  the  Lord;  and  like  a  hammer  that  breaketh  the  rock  in 
pieces  ?  ”  1  To  me  it  has  always  seemed  that  the  Prophet  had  in  his 
mind  a  simple,  archaic  form  of  mining  that  has  survived  to  the 
present  time  in  Southern  India.  A  huge  bonfire  is  kindled  on  a 
surface  of  rock,  and  after  heat  has  been  maintained  for  some  time 
the  fire  is  extinguished  and  the  rock  is  allowed  to  cool  down,  the 
result  being  that  a  few  feet  below  the  surface  a  rupture  takes  place 
parallel  to  the  external  slope  of  the  rock,  and  a  slab  is  detached, 
which  is  broken  up  in  the  usual  way,  with  hammers,  into  the  size 
and  shape  required.  At  Dartmoor  the  sun,  during  the  summer 
months,  has  acted  like  the  fire  of  the  Prophet,  and  the  frosts  of 
winter  have  completed  the  process.  Cracks,  small  at  first,  have 
1  Jeremiah,  xxiii.  29. 
