﻿Bocks, 
  in 
  Littleton, 
  New 
  Hampshire. 
  243 
  

  

  tively 
  so 
  much 
  more 
  plentiful 
  that 
  the 
  rock 
  must 
  be 
  called 
  a 
  

   qnartzite. 
  It 
  is 
  then 
  very 
  hard 
  and 
  white. 
  Ordinarily 
  such 
  

   quartzite 
  beds 
  are 
  not 
  more 
  than 
  five 
  or 
  six 
  feet 
  thick 
  and 
  do 
  

   not 
  extend 
  more 
  than 
  twenty 
  or 
  thirty 
  feet 
  along 
  the 
  strike. 
  

   They 
  are 
  purely 
  local. 
  

  

  Above 
  the 
  quartzite 
  or 
  the 
  arkose, 
  as 
  the 
  case 
  may 
  be, 
  and 
  

   sometimes 
  very 
  near 
  to 
  the 
  granite 
  gneiss, 
  is 
  the 
  limestone 
  that 
  

   carries 
  fossils 
  of 
  JSTiagaran 
  age. 
  This 
  limestone 
  is 
  of 
  a 
  bluish 
  

   gray 
  color 
  and 
  is 
  crystalline. 
  Since 
  we 
  found 
  that 
  it 
  had 
  cer- 
  

   tain 
  peculiarities 
  which 
  marked 
  it 
  as 
  different 
  from 
  other 
  lime- 
  

   stones 
  with 
  which 
  we 
  had 
  been 
  familiar, 
  we 
  studied 
  it 
  carefully. 
  

   In 
  an 
  outcrop 
  just 
  east 
  of 
  the 
  upper 
  right 
  corner 
  of 
  the 
  map 
  

   (iig. 
  2), 
  two 
  types 
  of 
  limestone 
  were 
  observed, 
  one 
  fine-grained 
  

   and 
  faintly 
  banded 
  and 
  the 
  other 
  coarse-grained. 
  These 
  two 
  

   kinds 
  occurred 
  as 
  separate, 
  pebble-like 
  bunches, 
  apparently 
  

   lying 
  in 
  all 
  attitudes 
  (banding), 
  and 
  enclosed 
  in 
  a 
  thin 
  paste 
  of 
  

   f 
  ossiliferous 
  calcareous 
  shale. 
  So 
  small 
  in 
  quantity 
  was 
  the 
  

   paste 
  and 
  so 
  similar 
  the 
  colors 
  of 
  the 
  two 
  types 
  that, 
  w 
  r 
  ith 
  three 
  

   or 
  four 
  exceptions, 
  the 
  outcrop 
  as 
  a 
  whole 
  seemed 
  to 
  be 
  com- 
  

   posed 
  of 
  uniform 
  limestone. 
  These 
  exceptions 
  were 
  rounded 
  

   pebbles 
  of 
  granite, 
  contained, 
  as 
  the 
  limestone 
  ' 
  bunches,' 
  in 
  

   the 
  fossiliferous 
  shaly 
  paste. 
  The 
  granite 
  of 
  these 
  pebbles 
  

   looked 
  strikingly 
  like 
  the 
  Fitch 
  Hill 
  granite 
  gneiss. 
  Many 
  of 
  

   the 
  limestone 
  ' 
  bunches 
  ' 
  held 
  crinoid 
  stems, 
  but 
  no 
  other 
  

   fossils. 
  In 
  the 
  shale 
  paste, 
  however, 
  were 
  numerous 
  remains 
  

   resembling 
  Stromatopora, 
  Syringopora, 
  and 
  Favosites. 
  

  

  On 
  Fitch 
  Hill, 
  where 
  Section 
  A 
  is 
  drawn, 
  the 
  conglomeratic 
  

   nature 
  of 
  the 
  limestone 
  is 
  not 
  so 
  evident 
  ; 
  but 
  there 
  are 
  indica- 
  

   tions 
  of 
  it. 
  In 
  this 
  connection 
  it 
  is 
  interesting 
  to 
  note 
  that 
  

   there 
  are 
  occasional 
  scattered, 
  lenticular 
  hollows, 
  elongate 
  

   parallel 
  to 
  the 
  strike 
  of 
  the 
  formation, 
  in 
  the 
  basal 
  arkose, 
  even 
  

   as 
  much 
  as 
  ten 
  feet 
  below 
  its 
  upper 
  'limit. 
  These 
  little 
  hollows 
  

   (average 
  : 
  8" 
  long, 
  2" 
  wide, 
  5" 
  deep) 
  are 
  isolated 
  pieces 
  of 
  

   limestone, 
  weathered 
  several 
  inches 
  below 
  the 
  surface 
  of 
  the 
  

   outcrop. 
  They 
  are 
  identical 
  with 
  the 
  ' 
  bunches 
  ' 
  in 
  the 
  eastern 
  

   outcrop 
  just 
  described. 
  

  

  Now, 
  these 
  observations, 
  if 
  correct, 
  point 
  to 
  limestones 
  of 
  

   .two 
  geologic 
  ages 
  in 
  the 
  Ammonoosuc 
  district. 
  Indeed, 
  our 
  

   investigations 
  in 
  other 
  parts 
  of 
  the 
  region 
  have 
  led 
  us 
  to 
  believe 
  

   that 
  some 
  of 
  the 
  limestones 
  hitherto 
  mapped 
  as 
  " 
  Mid-Upper 
  

   Silurian"* 
  contain 
  crinoid 
  stems, 
  but 
  no 
  fossils 
  distinctly 
  of 
  

   Niagaran 
  age. 
  This 
  matter 
  will 
  bear 
  more 
  thorough 
  study. 
  

  

  The 
  fossiliferous 
  slate 
  (third 
  member) 
  is 
  dark 
  gray 
  and 
  cal- 
  

   careous. 
  It 
  has 
  no 
  particular 
  importance 
  for 
  us, 
  and 
  will 
  not 
  

   be 
  described 
  at 
  greater 
  length. 
  

  

  Overlying 
  this 
  slate 
  are 
  the 
  non-fossiliferous 
  limestone 
  and 
  

  

  * 
  Hitchcock 
  : 
  New 
  Studies, 
  etc., 
  plate 
  43. 
  

  

  