﻿1864.] 
  MAW 
  SEVERN-VALLEY 
  DRIFT. 
  131 
  

  

  Cheshire, 
  and 
  extending 
  east 
  and 
  west 
  beyond 
  their 
  limits, 
  has 
  been 
  

   so 
  frequently 
  and 
  fully 
  written 
  upon, 
  by 
  Sir 
  R. 
  I. 
  Murchison 
  in 
  his 
  

   * 
  Silurian 
  System,' 
  by 
  the 
  Rev. 
  "W. 
  S. 
  Symonds 
  in 
  the 
  ' 
  Transac- 
  

   tions 
  of 
  the 
  Malvern 
  Naturalists' 
  Field-Club,' 
  by 
  Professor 
  Buckman 
  

   in 
  his 
  ' 
  Ancient 
  Straits 
  of 
  Malvern,' 
  and 
  by 
  Mr. 
  Prestwich, 
  the 
  Rev. 
  

   Mr. 
  Lister, 
  and 
  others 
  in 
  the 
  ' 
  Transactions 
  ' 
  and 
  ' 
  Quarterly 
  Journal 
  ' 
  

   of 
  the 
  Geological 
  Society, 
  that, 
  in 
  recording 
  my 
  observations, 
  I 
  am 
  

   enabled 
  to 
  add 
  but 
  little 
  to 
  what 
  is 
  already 
  known 
  ; 
  and 
  my 
  reason 
  

   for 
  making 
  a 
  further 
  communication 
  on 
  the 
  subject 
  is 
  that 
  some 
  re- 
  

   markably 
  good 
  sections 
  of 
  the 
  drift 
  have 
  recently 
  been 
  exposed 
  in 
  

   the 
  cuttings 
  of 
  the 
  Severn 
  Valley, 
  Wenlock, 
  and 
  Coalbrook 
  Dale 
  

   Railways, 
  some 
  of 
  which, 
  in 
  connexion 
  with 
  old 
  sections 
  exposed 
  in 
  

   gravel-pits, 
  enable 
  examination 
  to 
  be 
  made 
  of 
  superimposed 
  strata 
  

   upwards 
  of 
  200 
  feet 
  in 
  thickness. 
  

  

  Such 
  a 
  consecutive 
  thickness 
  of 
  post-tertiary 
  deposits 
  is 
  very 
  un- 
  

   common, 
  and 
  is 
  of 
  the 
  utmost 
  importance 
  for 
  comparison 
  with 
  more 
  

   fragmentary 
  examples, 
  and 
  for 
  ascertaining 
  to 
  what 
  extent 
  any 
  suc- 
  

   cession 
  and 
  order 
  of 
  deposition 
  of 
  the 
  constituent 
  strata 
  can 
  be 
  traced 
  

   between 
  the 
  drifts 
  of 
  different 
  localities 
  scattered 
  so 
  abundantly 
  

   over 
  the 
  south-west 
  of 
  England. 
  

  

  My 
  observations 
  have, 
  for 
  the 
  most 
  part, 
  been 
  limited 
  to 
  the 
  

   Severn 
  Valley, 
  from 
  about 
  four 
  miles 
  below 
  Bridgnorth 
  up 
  to 
  Shrews- 
  

   bury, 
  including 
  a 
  range 
  north 
  and 
  south 
  of 
  about 
  twenty 
  miles. 
  

  

  This 
  may 
  be 
  divided 
  into 
  three 
  distinct 
  districts 
  : 
  — 
  

  

  From 
  Shrewsbury 
  to 
  Buildwas 
  the 
  River 
  Severn 
  meanders 
  through 
  

   a 
  broad 
  valley, 
  at 
  an 
  average 
  level 
  of 
  about 
  110 
  feet 
  above 
  the 
  sea, 
  

   its 
  course 
  resting 
  upon 
  the 
  Bunter 
  Sandstone 
  and 
  Caradoc 
  Sandstone, 
  

   the 
  surfaces 
  of 
  which, 
  in 
  the 
  immediate 
  neighbourhood 
  of 
  the 
  river, 
  

   are 
  covered 
  by 
  perfectly 
  level 
  alluvium, 
  becoming, 
  however, 
  towards 
  

   its 
  boundary, 
  varied 
  by 
  rounded 
  hills 
  and 
  promontories 
  of 
  the 
  drift 
  

   about 
  to 
  be 
  described. 
  

  

  At 
  a 
  little 
  below 
  Buildwas, 
  12 
  or 
  13 
  miles 
  from 
  Shrewsbury, 
  the 
  

   valley 
  suddenly 
  contracts, 
  and 
  at 
  the 
  entrance 
  of 
  Coalbrook 
  Dale 
  the 
  

   river 
  breaks 
  through 
  the 
  great 
  Silurian 
  range 
  near 
  where 
  it 
  termi- 
  

   nates 
  on 
  the 
  east 
  side 
  of 
  the 
  river. 
  

  

  From 
  Buildwas 
  to 
  Coalbrook 
  Dale, 
  "Wenlock 
  shale 
  is 
  crossed 
  for 
  

   about 
  a 
  mile 
  ; 
  and 
  to 
  the 
  south 
  of 
  Coalbrook 
  Dale 
  the 
  great 
  Wenlock 
  - 
  

   limestone 
  escarpment, 
  including 
  Benthall 
  Edge 
  on 
  the 
  west 
  and 
  

   Lincoln 
  Hill 
  on 
  the 
  east, 
  guards 
  the 
  entrance 
  to 
  the 
  narrow 
  gorge 
  in 
  

   the 
  Coal-measures, 
  through 
  which 
  the 
  river 
  rapidly 
  descends 
  for 
  2\ 
  

   miles, 
  and 
  continues 
  in 
  a 
  series 
  of 
  rapids 
  to 
  Bridgnorth, 
  through 
  

   a 
  rather 
  narrow 
  valley 
  bounded 
  by 
  abrupt 
  cliffs 
  of 
  Lower 
  New 
  Red 
  

   and 
  Permian 
  sandstones. 
  The 
  flanks 
  of 
  this 
  gorge 
  seem 
  to 
  have 
  

   been 
  almost 
  entirely 
  denuded 
  of 
  drift, 
  and 
  for 
  some 
  miles 
  none, 
  of 
  

   any 
  extent, 
  is 
  to 
  be 
  seen 
  in 
  the 
  immediate 
  valley 
  of 
  the 
  Severn. 
  

  

  Below 
  Bridgnorth 
  the 
  valley 
  again 
  widens 
  out 
  into 
  a 
  tolerably 
  

   level 
  plain, 
  which 
  is 
  30 
  to 
  35 
  feet 
  lower 
  than 
  the 
  level 
  of 
  the 
  river 
  

   between 
  Shrewsbury 
  and 
  Buildwas, 
  and 
  from 
  60 
  to 
  70 
  feet 
  above 
  

   the 
  sea. 
  The 
  ground 
  in 
  the 
  immediate 
  neighbourhood 
  of 
  the 
  river 
  

   consists 
  of 
  flat 
  " 
  hams 
  " 
  or 
  alluvial 
  meadows 
  ; 
  from 
  these, 
  on 
  each 
  

  

  i2 
  

  

  