﻿1864.] 
  BIGSBY 
  MISSING 
  SEDIMENTARY 
  FORMATIONS. 
  221 
  

  

  Prof. 
  Ramsay* 
  finds 
  Wenlock 
  shale 
  resting 
  at 
  right 
  angles 
  on 
  up- 
  

   turned 
  Llandeilo 
  beds, 
  and 
  on 
  the 
  so-called 
  Cambrian 
  in 
  the 
  Shelve 
  

   and 
  Longmynd 
  countries, 
  as 
  well 
  as 
  near 
  Builth 
  in 
  Radnorshire 
  ; 
  the 
  

   gaps, 
  in 
  the 
  Professor's 
  opinion, 
  being 
  connected 
  with 
  denudation. 
  

  

  Chev. 
  Fr. 
  von 
  Hauer 
  f, 
  assisted 
  by 
  eminent 
  geologists, 
  has 
  exe- 
  

   cuted 
  a 
  section 
  across 
  the 
  Eastern 
  Alps, 
  from 
  Passau 
  to 
  the 
  Illyrian 
  

   Karst. 
  He 
  found 
  considerable 
  Silurian 
  beds 
  on 
  their 
  north 
  slopes, 
  

   while 
  on 
  their 
  south 
  flanks 
  these 
  rocks 
  are 
  unknown, 
  the 
  older 
  

   Carboniferous 
  occurring 
  in 
  their 
  place. 
  

  

  In 
  British 
  America, 
  according 
  to 
  Sir 
  W. 
  E. 
  Logan, 
  the 
  Lower 
  

   Silurian 
  occurs 
  as 
  tilted 
  strata 
  beneath 
  the 
  beds 
  of 
  the 
  Upper, 
  show- 
  

   ing 
  that 
  an 
  upheaval 
  had 
  occurred 
  before 
  the 
  latter 
  had 
  been 
  laid 
  

   down. 
  Similar 
  facts 
  have 
  been 
  observed 
  at 
  the 
  eastern 
  base 
  of 
  the 
  

   Green 
  Mountains 
  of 
  Vermont 
  (U. 
  S.), 
  where 
  limestones 
  of 
  Upper 
  

   Silurian 
  and 
  Devonian 
  age 
  rest 
  unconformably 
  on 
  the 
  altered 
  strata 
  

   of 
  the 
  Quebec 
  group 
  J. 
  

  

  Dr. 
  D. 
  D. 
  Owen 
  observed 
  §, 
  on 
  the 
  south 
  shore 
  of 
  Lake 
  Win- 
  

   nipeg 
  (Hudson's 
  Bay), 
  limestones 
  of 
  the 
  Lower 
  and, 
  perhaps, 
  of 
  the 
  

   Upper 
  Silurian 
  series 
  lying 
  on 
  granite 
  and 
  syenite, 
  without 
  the 
  

   usually 
  intervening 
  Primordial 
  zone 
  ; 
  as 
  we 
  likewise 
  abundantly 
  see 
  

   at 
  the 
  village 
  of 
  Lorette, 
  and 
  on 
  the 
  sides 
  of 
  Cap 
  Tourment, 
  both 
  

   near 
  Quebec 
  (Canada). 
  

  

  Wenlock 
  || 
  is 
  said 
  to 
  be 
  the 
  oldest 
  limestone 
  in 
  the 
  Arctic 
  regions. 
  

   If 
  this 
  be 
  so, 
  we 
  have 
  there 
  either 
  the 
  non-deposit 
  or 
  the 
  removal 
  

   of 
  the 
  whole 
  body 
  of 
  the 
  Lower 
  Silurian 
  series. 
  

  

  In 
  Iowa, 
  on 
  the 
  west 
  of 
  the 
  Mississippi, 
  the 
  upper 
  beds 
  of 
  the 
  

   Onondaga 
  salt-group 
  (Upper 
  Silurian) 
  are 
  water-worn, 
  and 
  some- 
  

   times 
  strewn 
  with 
  coarse 
  sand 
  and 
  gravel, 
  hardened 
  occasionally 
  

   into 
  little 
  patches 
  of 
  conglomerate 
  ; 
  thus 
  indicating, 
  says 
  Prof. 
  

   James 
  Hall 
  ^[, 
  a 
  lapse 
  of 
  time 
  before 
  the 
  deposit 
  of 
  the 
  next 
  suc- 
  

   ceeding 
  stratum, 
  some 
  representative 
  of 
  the 
  Lower 
  Helderberg 
  beds. 
  

   The 
  same 
  eminent 
  geologist 
  remarks 
  that 
  ten 
  of 
  the 
  seventeen 
  Si- 
  

   lurian 
  stages 
  found 
  in 
  the 
  State 
  of 
  New 
  York 
  are 
  wanting 
  on 
  the 
  

   north 
  of 
  the 
  River 
  Ohio, 
  or 
  west 
  of 
  Lake 
  Michigan 
  — 
  a 
  very 
  note- 
  

   worthy 
  fact 
  **. 
  

  

  Since 
  the 
  happiest 
  generalizations 
  must 
  rest 
  on 
  details, 
  I 
  am 
  sure 
  

   the 
  Society 
  will 
  pardon 
  the 
  length 
  of 
  these. 
  

  

  * 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  ix. 
  p. 
  175. 
  t 
  L'Institut, 
  1857, 
  p. 
  30. 
  

  

  X 
  Dana's 
  ' 
  Manual,' 
  p. 
  226. 
  § 
  Geol 
  Eeport, 
  Wisconsin, 
  p. 
  182. 
  

  

  || 
  Murchison, 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xi. 
  p. 
  537. 
  

   ^f 
  Palaeontology 
  of 
  New 
  York, 
  vol. 
  iii. 
  pp. 
  290, 
  &c. 
  

  

  ** 
  With 
  reference 
  to 
  a 
  few 
  other 
  instances 
  of 
  intervals 
  with 
  a 
  Silurian 
  roof, 
  

   consult 
  the 
  following 
  authorities 
  : 
  — 
  

  

  Delia 
  Marmora, 
  Geol. 
  of 
  Sardinia, 
  vol. 
  i. 
  p. 
  29 
  ; 
  on 
  Granite. 
  

   Sharpe, 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  ix. 
  p. 
  143 
  ; 
  conformably 
  on 
  Coal-measures, 
  

  

  at 
  Brazielo 
  and 
  Quinta 
  da 
  Lomba, 
  Portugal. 
  

   Tuomy, 
  Geol. 
  Kep. 
  Alabama, 
  p. 
  8 
  ; 
  on 
  old 
  Metamorphic 
  rocks, 
  extensively. 
  

   Hall, 
  Palaeontology 
  of 
  New 
  York, 
  vol. 
  ii. 
  (introductory 
  review) 
  pp. 
  20, 
  22, 
  46 
  ; 
  

   absence 
  of 
  various 
  important 
  parts 
  of 
  the 
  Silurian 
  system. 
  Vol. 
  iii. 
  p. 
  36 
  ; 
  

   Lower 
  Helderberg 
  rocks 
  on 
  Utica 
  Slate. 
  

   Murchison. 
  See 
  'Siluria,' 
  2nd 
  edit. 
  p. 
  Ill 
  ; 
  Pentamerus-sandstone, 
  at 
  May 
  Hill, 
  

   on 
  unfossiliferous 
  slate 
  (below 
  Lingula-flags). 
  

  

  