﻿206 
  PROF. 
  E. 
  HULL 
  Otf 
  A 
  PKOPOSED 
  

  

  mity 
  of 
  the 
  Dingle 
  promontory 
  in 
  1878, 
  and 
  seeing 
  the 
  perfect 
  con- 
  

   tinuity 
  between 
  the 
  Dingle 
  beds 
  and 
  the 
  underlying 
  Upper 
  Silurian 
  

   strata, 
  I 
  came 
  to 
  the 
  conclusion 
  that 
  they 
  themselves 
  were 
  an 
  

   upper 
  portion 
  of 
  the 
  Silurian 
  series*, 
  representing 
  the 
  Upper 
  

   Ludlow 
  rocks 
  — 
  a 
  view 
  previously 
  advanced 
  by 
  Sir 
  R. 
  Griffith. 
  

   Taking 
  into 
  consideration, 
  however, 
  the 
  prodigious 
  development 
  of 
  

   these 
  beds, 
  and 
  the 
  consequent 
  lapse 
  of 
  time 
  during 
  which 
  they 
  

   must 
  have 
  been 
  in 
  course 
  of 
  accumulation, 
  their 
  geographical 
  im- 
  

   portance, 
  and 
  their 
  connexion 
  on 
  the 
  one 
  hand 
  with 
  the 
  Devonian 
  

   (by 
  inference), 
  and 
  on 
  the 
  other 
  with 
  the 
  Silurian 
  system 
  (by 
  ob- 
  

   servation), 
  I 
  now 
  prefer 
  to 
  place 
  them 
  in 
  the 
  position 
  of 
  a 
  separate 
  

   group, 
  under 
  the 
  stjle 
  and 
  title 
  of 
  " 
  Devono-Silurian 
  "f 
  . 
  

  

  Ireland, 
  North 
  ( 
  t; 
  Fintona 
  beds*') 
  . 
  — 
  This 
  group 
  is 
  also 
  represented 
  

   in 
  the 
  north 
  of 
  Ireland 
  by 
  a 
  great 
  series 
  of 
  reddish 
  grits, 
  conglome- 
  

   rates, 
  and 
  shales, 
  lying 
  between 
  the 
  valleys 
  of 
  Loughs 
  Erne 
  and 
  

   Xeagh, 
  and 
  forming 
  large 
  portions 
  of 
  Monaghan 
  and 
  Tyrone. 
  Their 
  

   base 
  reposes 
  either 
  on 
  the 
  metamorphic 
  rocks 
  of 
  the 
  north 
  of 
  Ireland 
  

   or 
  (unconformably) 
  on 
  the 
  Lower 
  Silurian 
  beds 
  of 
  Pomeroy, 
  charged 
  

   with 
  fossils 
  of 
  " 
  Caradoc 
  (Bala) 
  '*' 
  genera 
  and 
  species, 
  as 
  originally 
  

   shown 
  by 
  Portlock. 
  In 
  this 
  case 
  the 
  Upper 
  Silurian 
  beds 
  are 
  absent, 
  

   and 
  we 
  have 
  a 
  hiatus 
  at 
  the 
  base 
  of 
  the 
  series, 
  which 
  is 
  filled 
  up 
  

   in 
  the 
  Dingle 
  promontory 
  ; 
  nevertheless 
  there 
  is 
  a 
  general 
  consensus 
  

   amongst 
  Irish 
  geologists 
  that 
  the 
  " 
  Fintona 
  beds," 
  as 
  they 
  are 
  now 
  

   frequently 
  designated, 
  arc 
  the 
  representatives 
  in 
  time 
  of 
  the 
  Dingle 
  

   and 
  Glengariff 
  beds; 
  and 
  as 
  such 
  they 
  would 
  come 
  under 
  the 
  

   designation 
  of 
  " 
  Devono-Silurian." 
  

  

  The 
  position 
  of 
  these 
  beds 
  serves 
  to 
  connect 
  them 
  geographically 
  

   with 
  their 
  Scottish 
  representatives, 
  which 
  I 
  next 
  proceed 
  to 
  refer 
  to 
  ; 
  

   but 
  they 
  have 
  not 
  hitherto 
  (like 
  the 
  latter) 
  yielded 
  ichthyic 
  remains, 
  

   or, 
  indeed, 
  fossils 
  of 
  any 
  kind. 
  They 
  were 
  probably 
  deposited 
  within 
  

   the 
  margin 
  of 
  a 
  lake-basin, 
  bounded 
  in 
  nearly 
  all 
  directions 
  by 
  unsub- 
  

   merged 
  lands 
  formed 
  of 
  Lower 
  Silurian 
  rocks 
  towards 
  the 
  south, 
  and 
  

   of 
  their 
  metamorphosed 
  representatives 
  towards 
  the 
  north. 
  East- 
  

   wards 
  this 
  basin 
  may 
  have 
  been 
  connected 
  by 
  a 
  narrow 
  channel 
  with 
  

   Professor 
  Geikie's 
  " 
  Lake 
  Caledonia 
  or 
  Mid-Scottish 
  Basin," 
  through 
  

   the 
  Firth 
  of 
  Clyde, 
  as 
  he 
  himself 
  has 
  suggested 
  J. 
  

  

  (e) 
  Scotland.' 
  — 
  It 
  can 
  scarcely 
  be 
  a 
  question 
  that 
  the 
  beds 
  known 
  

   in 
  Scotland 
  as 
  " 
  Lower 
  Old 
  lied 
  Sandstone 
  " 
  are 
  referable 
  to 
  the 
  

   group 
  I 
  am 
  now 
  describing. 
  Professor 
  Geikie 
  has 
  already 
  suggested 
  

   that 
  they 
  are 
  represented 
  in 
  Ireland 
  by 
  the 
  Glengariff 
  or 
  Dingle 
  

   beds, 
  a 
  view 
  in 
  which 
  I 
  concur 
  ; 
  and 
  that 
  there 
  is 
  no 
  palwontological 
  

   difficulty 
  in 
  the 
  way 
  of 
  the 
  acceptance 
  of 
  this 
  view 
  may 
  be 
  inferred 
  

  

  * 
  " 
  On 
  the 
  Geological 
  Age 
  of 
  the 
  Rocks 
  forming 
  the 
  Southern 
  Highlands 
  of 
  

   Ireland," 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xxxv. 
  p. 
  699 
  et 
  seqq. 
  (1879). 
  

  

  t 
  We 
  have 
  as 
  yet 
  no 
  evidence 
  from 
  fossils 
  regarding 
  the 
  conditions 
  of 
  

   formation 
  of 
  these 
  beds. 
  Careful 
  examination 
  by 
  the 
  officers 
  of 
  the 
  Geological 
  

   Survey 
  has 
  hitherto 
  failed 
  to 
  bring 
  to 
  light 
  any 
  thing 
  but 
  plants, 
  Fucoids, 
  and 
  

   Annelid-tracks. 
  I 
  incline 
  to 
  the 
  opinion 
  that 
  they 
  were 
  of 
  marine 
  origin. 
  

  

  % 
  "On 
  the 
  Old 
  Red 
  Sandstone 
  of 
  Western 
  Europe."— 
  Trans. 
  Roy. 
  Soc. 
  

   Edinb. 
  (1878). 
  

  

  