516  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1903.  [bull.  225. 
which  were  visited,  but  no  extensive  deposits  were  seen.  In  the 
residual  deposits  the  masses  average  6  to  8  inches  in  diameter,  are 
rough  in  outline  bearing  casts  of  dissolved  angular  fragments  of  lime- 
stone, and  are  considerably  weathered.  Two  of  the  openings  visited 
are  in  bed  rock.  Here  the  barite  is  chiefly  massive,  banded,  subcrys- 
talline  or  granular,  and  milky,  resembling  chert,  but  is  in  part  clear 
and  crystalline.  It  occurs  as  a  vein  filling  in  the  brecciated  limestone. 
Such  deposits  are  not  profitable,  as  the  ore  must  be  crushed  and  sepa- 
rated from  the  rock;  consequently  they  have  been  but  little  developed. 
The  deposits  occur  in  the  folded  and  brecciated  portions  of  the  lime- 
stone, and,  in  one  case  at  least,  in  the  arch  of  a  plunging  anticline  asso- 
ciated with  the  hard  sandstone  at  the  top  of  the  lower  division,  a 
favorable  position  for  the  brecciation  of  the  limestone.  Barite  was 
deposited  in  the  crevices  of  the  breccia  and  has  cemented  it  together. 
Being  restricted  in  occurrence  to  the  upper  part  of  the  lower  division 
of  the  limestone  series,  the  deposit,  it  appears,  is  due  to  local  segrega- 
tion of  disseminated  barite  from  the  adjacent  limestone.  Vein  quartz 
with  comb  structure,  which  occurs  frequently  in  strata  just  below  this 
horizon,  also  seems  to  be  due  to  local  segregation. 
The  barite  deposits  visited  are  as  follows:  Snowbarger's  prospect, 
vein  deposit  top  of  hill  2  miles  northeast  of  Waynesboro;  Trimp 
Riley's  deposit  on  the  northern  slope  of  the  same  hill,  probably  derived 
from  the  former  vein;  Bonebrake's  deposit,  3J  miles  east  of  town;  and 
two  openings  by  Mr.  Stamey,  4^  miles  north  of  town — one  a  vein,  the 
other  an  associated  residuum  deposit. 
In  the  same  general  region,  but  on  the  west  side  of  Cumberland 
Valley,  very  pure  limestone  beds  occur  in  the  top  of  the  Cambro- 
Ordovician  limestone  series.  No  great  thickness  of  this  pure  lime- 
stone was  observed  in  this  immediate  region,  but  southward  along  the 
same  belt  at  Martinsburg,  W.  Va.,  this  limestone  is  exceptionally  pure 
and  very  thick.  It  has  been  quarried  there  on  a  vast  scale  by  the 
Standard  Lime  and  Stone  Company  for  use  as  flux  in  the  iron  furnaces 
about  Pittsburg. 
The  limestone  outcrops  in  a  belt  extending  southward  from  the 
town.  On  the  east  side  is  a  low  ridge  of  Hudson  shale  containing 
graptolites  of  Utica  age  near  the  base.  Dipping  at  an  angle  of  20 
degrees  under  these  beds  are  90  feet  of  dark,  compact,  crystalline  and 
shaly  limestones  bearing  fossils  of  Trenton  age.  Below  this  are  three 
or  four  heavy  beds  of  pure  limestone  averaging  15  to  20  feet  in  thick- 
ness, with  a  total  of  about  80  feet.  This  is  the  deposit  that  is  quarried. 
The  upper  bed  is  a  very  massive,  compact,  light-gray  limestone, 
weathering  chalky  white  on  the  surface,  with  smooth  fracture  and  but 
slight  indications  of  bedding.  The  lower  beds  are  darker,  coarser 
grained,  not  so  homogeneous,  and  have  a  rough  fracture,  and  at  the 
