﻿SEPT. 
  19, 
  1922 
  STOSE 
  AND 
  JONAS 
  : 
  LOWER 
  PALEOZOIC 
  OF 
  PENNSYLVANIA 
  361 
  

  

  apparently 
  pebbles 
  derived 
  from 
  the 
  disintegration 
  of 
  the 
  underlying 
  

   greenstone 
  and 
  aporhyolite. 
  The 
  higher 
  beds 
  are 
  dark 
  slate 
  and 
  

   pebbly 
  vitreous 
  quartzite 
  with 
  interbedded 
  coarse 
  conglomerate 
  

   which 
  is 
  made 
  up 
  of 
  crowded 
  round 
  white 
  quartz 
  pebbles, 
  2 
  to 
  4 
  inches 
  

   in 
  diameter, 
  in 
  a 
  sericitic 
  siliceous 
  matrix. 
  The 
  thickness 
  of 
  the 
  

   Hellam 
  conglomerate 
  is 
  estimated 
  to 
  be 
  600 
  feet. 
  

  

  The 
  Chickies 
  quartzite 
  as 
  exposed 
  in 
  Chickies 
  Rock 
  is 
  a 
  heavy- 
  

   bedded 
  light-colored 
  vitreous 
  quartzite 
  and 
  grainy 
  quartzite 
  with 
  

   slate 
  interbedded 
  near 
  the 
  top, 
  400 
  feet 
  thick. 
  The 
  quartzite 
  carries 
  

   Scolithus 
  tubes 
  throughout. 
  It 
  is 
  similar 
  to 
  the 
  Montalto 
  quartzite 
  

   member 
  of 
  the 
  Harpers 
  schist 
  of 
  South 
  Mountain 
  but 
  as 
  it 
  lies 
  at 
  the 
  

   base 
  of 
  the 
  Harpers 
  and 
  not 
  in 
  its 
  midst, 
  it 
  is 
  probably 
  not 
  the 
  exact 
  

   equivalent 
  of 
  the 
  Montalto. 
  The 
  Chickies 
  quartzite, 
  including 
  the 
  

   Hellam 
  conglomerate 
  member, 
  is 
  about 
  1000 
  feet 
  thick. 
  

  

  The 
  Harpers 
  formation 
  of 
  the 
  Hellam- 
  Chickies 
  Hills 
  is 
  a 
  greenish 
  

   gray 
  phylHte 
  with 
  some 
  biotite.^ 
  The 
  bedding 
  of 
  the 
  phyllite 
  cannot 
  

   be 
  determined 
  in 
  most 
  places, 
  but 
  the 
  interbedded 
  quartzite 
  layers 
  

   show 
  several 
  close 
  folds. 
  Although 
  the 
  thickness 
  cannot 
  be 
  accurately 
  

   determined 
  it 
  is 
  estimated 
  to 
  be 
  1000 
  feet. 
  The 
  phyllite 
  is 
  overlain 
  by 
  

   light 
  gray, 
  somewhat 
  calcareous, 
  vitreous 
  and 
  granular 
  impure 
  quartz- 
  

   ites, 
  about 
  200 
  feet 
  thick, 
  some 
  of 
  the 
  upper 
  beds 
  of 
  which 
  weather 
  

   to 
  a 
  laminated, 
  porous, 
  highly 
  ferruginous 
  rock. 
  These 
  upper 
  beds 
  

   have 
  the 
  characteristics 
  of 
  certain 
  fossiliferous 
  beds 
  of 
  the 
  Antietam 
  

   sandstone 
  of 
  South 
  Mountain, 
  and 
  their 
  bedding 
  surfaces 
  show 
  nu- 
  

   merous 
  rusty 
  molds 
  of 
  Ohelella 
  and 
  trilobite 
  fragments. 
  This 
  quartzite 
  

   is 
  therefore 
  equivalent 
  to 
  the 
  Antietam 
  sandstone 
  (quartzite) 
  of 
  

   South 
  Mountain. 
  

  

  The 
  senior 
  author 
  has 
  recognized 
  in 
  Welsh 
  Mountain 
  and 
  vicinity 
  

   the 
  same 
  divisions 
  of 
  the 
  Lower 
  Cambrian 
  arenaceous 
  series 
  as 
  are 
  

   found 
  in 
  the 
  Hellam-Chickies 
  Hills. 
  The 
  Hellam 
  conglomerate 
  

   member 
  in 
  Welsh 
  Mountain 
  is 
  made 
  up 
  of 
  a 
  grainy 
  to 
  finely 
  conglom- 
  

   eratic 
  quartzite 
  and 
  coarse 
  quartzose 
  conglomerate 
  at 
  the 
  base, 
  

   some 
  of 
  the 
  pebbles 
  of 
  which 
  are 
  of 
  clear 
  blue 
  quartz. 
  The 
  chloritic 
  

   schist 
  which 
  occurs 
  at 
  the 
  base 
  of 
  the 
  section 
  in 
  the 
  Hellam 
  anticline 
  

   is 
  here 
  absent 
  because 
  the 
  pre-Cambrian 
  rocks 
  of 
  the 
  Welsh 
  Mountain 
  

   region 
  from 
  which 
  the 
  arenaceous 
  Cambrian 
  rocks 
  were 
  derived 
  is 
  

  

  ' 
  The 
  rock 
  of 
  the 
  Harpers 
  formation 
  in 
  the 
  Hellam-Chickies 
  and 
  Welsh 
  Motmtain 
  anti- 
  

   clines 
  is 
  referred 
  to 
  here 
  as 
  a 
  phyllite 
  to 
  distinguish 
  it 
  from 
  the 
  more 
  metamorphosed 
  rock 
  

   on 
  the 
  flanks 
  of 
  Mine 
  Ridge, 
  which 
  is 
  a 
  schist. 
  The 
  senior 
  author 
  would 
  prefer 
  to 
  use 
  the 
  

   term 
  Harpers 
  schist 
  in 
  both 
  areas, 
  which 
  name 
  he 
  has 
  used 
  in 
  previous 
  publications 
  on 
  the 
  

   South 
  Mountain. 
  

  

  