﻿1804.] 
  MAW 
  SEVEBK-VALLEY 
  DRIFT. 
  139 
  

  

  On 
  the 
  high 
  ground 
  to 
  the 
  south-west 
  of 
  Bridgnorth, 
  in 
  the 
  direc- 
  

   tion 
  of 
  Wolverhampton, 
  blocks 
  of 
  grey 
  granite 
  are 
  most 
  abundant 
  ; 
  

   and 
  at 
  Burton, 
  3| 
  miles 
  to 
  the 
  west 
  of 
  Much 
  Wenlock, 
  a 
  consider- 
  

   able 
  area 
  of 
  ground, 
  extending 
  from 
  700 
  to 
  800 
  feet 
  above 
  the 
  

   sea, 
  is 
  thickly 
  strewn 
  with 
  them, 
  where 
  they 
  are 
  accompanied 
  by 
  a 
  

   bed 
  of 
  smaller 
  water-worn 
  gravel 
  or 
  shingle, 
  mostly 
  composed 
  of 
  

   granitic 
  detritus, 
  and 
  having 
  no 
  apparent 
  stratification. 
  The 
  fine 
  

   matter 
  of 
  this 
  bed 
  is 
  of 
  a 
  loamy 
  character, 
  and 
  the 
  absence 
  of 
  the 
  

   beds 
  of 
  clean 
  sand 
  occurring 
  at 
  lower 
  levels 
  is 
  noticeable. 
  

  

  The 
  local 
  distribution 
  of 
  these 
  boulders 
  is 
  rather 
  remarkable. 
  In 
  

   some 
  places, 
  as 
  at 
  Burton, 
  the 
  ground 
  is 
  thickly 
  strewn 
  with 
  them, 
  

   and, 
  again, 
  at 
  similar 
  elevations 
  over 
  considerable 
  areas 
  they 
  are 
  

   almost 
  entirely 
  absent. 
  

  

  I 
  would 
  suggest 
  that 
  their 
  partial 
  distribution 
  may 
  be 
  accounted 
  

   for 
  by 
  supposing 
  that 
  they 
  were 
  not 
  merely 
  casually 
  dropped 
  from 
  

   floating 
  icebergs, 
  but 
  deposited 
  wherever 
  they 
  happened 
  to 
  ground. 
  

   Otherwise 
  the 
  tendency 
  would 
  be 
  for 
  the 
  low 
  ground, 
  which 
  was 
  

   longer 
  under 
  water 
  than 
  the 
  higher 
  hills, 
  to 
  receive 
  a 
  larger 
  instead 
  

   of 
  a 
  smaller 
  proportion 
  of 
  them. 
  

  

  The 
  fossils 
  found 
  in 
  the 
  drift 
  -beds, 
  in 
  the 
  determination 
  of 
  which 
  

   I 
  have 
  been 
  kindly 
  assisted 
  by 
  Mr. 
  Gwyn 
  Jeffreys 
  and 
  also 
  by 
  Mr. 
  

   Etheridge 
  (of 
  the 
  Geological 
  Survey), 
  Dr. 
  Duncan, 
  and 
  Mr. 
  Jenkins, 
  

   consist 
  of 
  various 
  marine 
  organisms, 
  sparingly 
  distributed, 
  and 
  

   including 
  fossils 
  from 
  the 
  Silurian, 
  Carboniferous, 
  Liassic, 
  and 
  Chalk 
  

   formations 
  ; 
  and 
  the 
  vertebra 
  of 
  an 
  aquatic 
  Fowl 
  has 
  recently 
  been 
  

   found 
  in 
  the 
  gravel 
  near 
  Buildwas 
  Abbey, 
  but 
  I 
  do 
  not 
  think 
  it 
  

   coeval 
  with 
  the 
  drift. 
  No 
  Mammalian 
  remains 
  have 
  yet 
  been 
  detected. 
  

   I 
  have 
  endeavoured 
  to 
  ascertain 
  whether 
  any 
  species 
  are 
  peculiar 
  to 
  

   particular 
  parts 
  of 
  the 
  deposit, 
  but 
  find 
  that, 
  like 
  the 
  rocky 
  consti- 
  

   tuents, 
  they 
  are 
  indiscriminately 
  distributed 
  through 
  the 
  whole 
  mass 
  

   of 
  drift, 
  including 
  the 
  clay- 
  and 
  gravel-beds. 
  In 
  the 
  clay 
  the 
  whole 
  

   of 
  the 
  Shells 
  were 
  exceedingly 
  soft, 
  and 
  difficult 
  to 
  extricate 
  without 
  

   breaking, 
  and 
  the 
  more 
  perfect 
  examples 
  were 
  obtained 
  from 
  some 
  

   thin 
  beds 
  of 
  fine 
  gravel 
  immediately 
  over 
  and 
  under 
  it 
  ; 
  but, 
  out 
  

   of 
  several 
  hundred 
  examples, 
  not 
  above 
  six 
  or 
  seven 
  are 
  quite 
  

   perfect. 
  Of 
  that 
  massive 
  and 
  strong 
  shell, 
  Cyprina 
  Islandica, 
  I 
  have 
  

   detected 
  nothing 
  but 
  fragments 
  scarcely 
  an 
  inch 
  across, 
  and 
  mostly 
  

   much 
  smaller. 
  The 
  broken 
  and 
  water-worn 
  condition 
  of 
  these 
  remains 
  

   would 
  support 
  the 
  idea 
  of 
  their 
  long 
  transit 
  from 
  perhaps 
  northern 
  

   latitudes 
  ; 
  but 
  the 
  evidence 
  before 
  us 
  of 
  the 
  repeated 
  tearing-up 
  and 
  

   redeposition 
  of 
  the 
  beds 
  in 
  which 
  they 
  occur 
  would 
  also 
  account 
  for 
  

   their 
  fragmentary 
  state. 
  Mr. 
  Jeffreys 
  has, 
  in 
  the 
  second 
  volume 
  of 
  

   his 
  ' 
  British 
  Conchology 
  ' 
  (p. 
  306), 
  offered 
  another 
  explanation 
  of 
  

   the 
  condition 
  in 
  which 
  Cyprina 
  Islandica 
  occurs 
  in 
  the 
  Boulder- 
  

   clay. 
  

  

  At 
  the 
  point 
  where 
  the 
  drift-beds 
  rest 
  against 
  the 
  old 
  coast-line 
  

   of 
  Wenlock 
  shale 
  I 
  made 
  a 
  careful 
  examination 
  of 
  the 
  water- 
  worn 
  

   surface, 
  with 
  the 
  object 
  of 
  ascertaining 
  if 
  some 
  of 
  the 
  Shells 
  occurred 
  

   in 
  situ, 
  but 
  found 
  nothing 
  different 
  from 
  the 
  usual 
  state 
  : 
  all 
  were 
  

   broken 
  and 
  fragmentary. 
  

  

  