﻿134 
  PROCEEDINGS 
  OE 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  [Jan. 
  20, 
  

  

  freshwater 
  low 
  -level 
  drifts 
  of 
  the 
  Avon 
  and 
  Lower 
  Severn, 
  must 
  have 
  

   been 
  first 
  formed, 
  as 
  it 
  is 
  merely 
  a 
  continuation 
  of 
  the 
  gravel-beds 
  

   upon 
  which 
  the 
  upper 
  strata 
  of 
  Strethill 
  repose. 
  

  

  The 
  following 
  is 
  a 
  list 
  of 
  the 
  rocks 
  occurring 
  in 
  the 
  drift 
  between 
  

   Ironbridge 
  and 
  Shrewsbury. 
  I 
  have 
  avoided 
  naming 
  them 
  before, 
  

   because 
  the 
  list 
  applies 
  equally 
  to 
  every 
  bed 
  composing 
  the 
  drift, 
  and 
  

   from 
  careful 
  observation 
  I 
  cannot 
  find 
  that 
  the 
  constituent 
  rocks 
  of 
  

   the 
  water- 
  worn 
  gravels 
  differ 
  from 
  those 
  in 
  the 
  clay-bed, 
  or 
  the 
  larger 
  

   masses 
  from 
  the 
  smaller 
  materials. 
  

  

  The 
  only 
  constant 
  fact 
  that 
  impresses 
  one 
  is 
  the 
  very 
  large 
  propor- 
  

   tion 
  of 
  the 
  constituents 
  that 
  appear 
  to 
  be 
  of 
  local 
  origin, 
  the 
  varia- 
  

   tions 
  of 
  colour 
  and 
  character 
  being 
  dependent 
  on 
  purely 
  local 
  circum- 
  

   stances. 
  All 
  who 
  have 
  noticed 
  the 
  superficial 
  gravel- 
  deposits 
  distri- 
  

   buted 
  throughout 
  the 
  kingdom 
  cannot 
  fail 
  to 
  trace 
  their 
  variations 
  of 
  

   colour, 
  &c, 
  to 
  their 
  evident 
  derivation 
  from 
  neighbouring 
  formations. 
  

   The 
  orange-coloured 
  gravels 
  about 
  London 
  and 
  in 
  the 
  south-east 
  of 
  

   England 
  probably 
  derive 
  their 
  colour 
  from 
  the 
  ferruginous 
  beds 
  of 
  

   the 
  Greensand 
  formation, 
  and 
  a 
  similar 
  relation 
  of 
  colour 
  and 
  mate- 
  

   rial 
  can 
  be 
  traced 
  between 
  the 
  New 
  Red 
  Sandstone 
  and 
  the 
  gravels 
  

   that 
  rest 
  upon 
  it. 
  

  

  In 
  the 
  following 
  list 
  of 
  the 
  rocks 
  of 
  the 
  Severn-Valley 
  drift, 
  I 
  

   have 
  given 
  the 
  nearest 
  direct 
  distance 
  of 
  the 
  parent 
  formation 
  in 
  situ. 
  

  

  List 
  of 
  Mods 
  occurring 
  in 
  the 
  Drift 
  of 
  the 
  Severn 
  Valley. 
  

  

  Flints, 
  fragments 
  of 
  hard 
  chalk, 
  and 
  chalk 
  Corals 
  in 
  small 
  num- 
  

   bers 
  (80 
  miles 
  to 
  the 
  S.E., 
  100 
  miles 
  to 
  the 
  N.E.). 
  

   Oolitic 
  limestone, 
  a 
  fragment 
  (from 
  40 
  miles 
  to 
  the 
  south). 
  

   Lias 
  fossils, 
  including 
  Cardinia 
  ovalis 
  from 
  the 
  Lower 
  Lias, 
  Gry- 
  

   phcea 
  incurva, 
  &c. 
  (20 
  miles 
  to 
  the 
  north, 
  and 
  30 
  miles 
  to 
  the 
  

  

  south). 
  

   Bunter 
  sandstone 
  in 
  fragments 
  and 
  as 
  sand 
  (4 
  miles 
  to 
  the 
  N.AV. 
  

  

  and 
  4 
  miles 
  to 
  the 
  S.E.). 
  

   Permian, 
  sandstone 
  (2-1 
  miles 
  to 
  the 
  S.E.). 
  

   Coal-measure 
  rocks 
  and 
  fossils, 
  drift 
  coal, 
  and 
  nodules 
  of 
  ironstone 
  

  

  in 
  large 
  quantities 
  (1 
  mile 
  to 
  the 
  S.E.). 
  

   Mountain-limestone 
  in 
  large 
  masses 
  (2 
  miles 
  to 
  the 
  north). 
  

   Old 
  Red 
  Sandstone 
  (4 
  miles 
  to 
  the 
  south). 
  

   AVenlock 
  shale 
  Trilobites 
  (Phacops 
  longicaudatus), 
  Corals, 
  and 
  Shells 
  

  

  (immediately 
  adjacent). 
  

   Wenlock 
  limestone 
  and 
  characteristic 
  Shells 
  and 
  Corals 
  (\ 
  mile 
  to 
  

  

  the 
  S.W.). 
  

   Llandovery 
  sandstone 
  and 
  Caradoc 
  sandstone 
  abundant 
  (3 
  miles 
  

  

  to 
  the 
  west). 
  

   Cambrian 
  rocks 
  (12 
  miles 
  to 
  the 
  west). 
  

   Greenstone 
  abundant 
  (evidently 
  derived 
  from 
  the 
  Wrekin, 
  3 
  miles 
  

  

  to 
  the 
  N/W.). 
  

   Various 
  granites 
  from 
  Cumberland 
  (120 
  miles 
  to 
  the 
  north), 
  and 
  

  

  perhaps 
  from 
  Scotland. 
  

   Porphyritic 
  syenite, 
  probably 
  from 
  the 
  Maiverns 
  (35 
  miles 
  to 
  the 
  

  

  south). 
  

   Trap 
  -ash. 
  

  

  