﻿54 
  

  

  PKOCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  

  

  the 
  subject 
  being 
  regarded 
  as 
  not 
  sufficiently 
  studied. 
  To 
  one 
  of 
  

   the 
  observations, 
  however, 
  which 
  appears 
  to 
  me 
  very 
  important, 
  I 
  

   shall 
  revert 
  presently. 
  

  

  The 
  Bologna 
  Congress, 
  it 
  will 
  be 
  recollected, 
  only 
  decided 
  upon 
  the 
  

   colours 
  for 
  Pre-Cambrian 
  and 
  Mesozoic 
  rocks, 
  and 
  in 
  doing 
  so 
  

   accepted 
  Prof. 
  Renevier's 
  proposals, 
  with 
  the 
  exception 
  that, 
  on 
  his 
  

   own 
  recommendation, 
  violet 
  was 
  adopted 
  for 
  Trias 
  instead 
  of 
  brick- 
  

   red, 
  as 
  had 
  been 
  proposed 
  in 
  the 
  printed 
  Report. 
  Yellow 
  tints 
  were 
  

   accepted 
  for 
  Tertiary 
  systems, 
  the 
  higher 
  beds 
  to 
  be 
  represented 
  by 
  

   paler 
  shades. 
  The 
  selection 
  of 
  hues 
  for 
  Palaeozoic 
  rocks, 
  and 
  the 
  

   whole 
  question 
  of 
  the 
  coloration 
  to 
  be 
  adopted 
  for 
  igneous 
  forma- 
  

   tions, 
  were 
  referred 
  to 
  a 
  committee 
  appointed 
  to 
  arrange 
  for 
  the 
  

   publication 
  of 
  a 
  geological 
  map 
  of 
  Europe. 
  

  

  There 
  can 
  be 
  little 
  doubt 
  that 
  the 
  adoption, 
  almost 
  without 
  

   discussion, 
  of 
  a 
  different 
  colour 
  from 
  that 
  originally 
  recommended 
  

   for 
  the 
  Trias, 
  was 
  one 
  of 
  the 
  greatest 
  mistakes 
  made 
  by 
  the 
  

   Congress. 
  The 
  question 
  should 
  have 
  been 
  postponed. 
  But, 
  in 
  

   point 
  of 
  fact, 
  the 
  question 
  of 
  the 
  colours 
  to 
  be 
  adopted 
  for 
  maps 
  is 
  

   one 
  of 
  which 
  very 
  few 
  geologists 
  have 
  any 
  wide 
  experience, 
  and 
  it 
  

   is 
  consequently 
  one 
  which 
  a 
  congress 
  of 
  geologists 
  is 
  ill 
  qualified 
  to 
  

   discuss. 
  

  

  Before 
  passing 
  away 
  from 
  Prof. 
  Renevier's 
  Report, 
  it 
  is 
  as 
  well 
  to 
  

   call 
  attention 
  to 
  the 
  circumstance 
  that 
  some 
  very 
  useful 
  proposals 
  

   were 
  accepted 
  unanimously 
  by 
  the 
  Congress. 
  These 
  were 
  : 
  — 
  (1) 
  That 
  

   different 
  shades 
  of 
  a 
  colour 
  (or, 
  as 
  some 
  express 
  it, 
  different 
  tones 
  of 
  

   a 
  hue) 
  should 
  be 
  adopted 
  for 
  subdivisions 
  of 
  a 
  system, 
  the 
  darkest 
  

   shade 
  being 
  employed 
  for 
  the 
  oldest 
  subdivision; 
  (2) 
  That 
  the 
  

   lettering 
  or 
  literal 
  notation 
  for 
  sedimentary 
  rocks 
  in 
  general 
  should 
  

   be 
  founded 
  on 
  the 
  Latin 
  alphabet, 
  and 
  that 
  for 
  igneous 
  rocks 
  on 
  the 
  

   Greek 
  ; 
  (3) 
  That 
  each 
  sedimentary 
  system 
  should 
  be 
  represented 
  by 
  

   a 
  corresponding 
  capital 
  letter 
  (e. 
  g., 
  Jurassic 
  by 
  J), 
  principal 
  sub- 
  

   divisions 
  of 
  each 
  system 
  by 
  the 
  addition 
  of 
  a 
  small 
  initial 
  letter 
  

   (Portlandian 
  by 
  Jp), 
  and 
  the 
  minor 
  subdivisions 
  by 
  figures 
  (Jp 
  1 
  , 
  

   Jp 
  2 
  , 
  &c), 
  the 
  most 
  ancient 
  of 
  the 
  latter 
  being 
  represented 
  by 
  the 
  

   lowest 
  figure. 
  

  

  One 
  other 
  contribution 
  to 
  the 
  question 
  of 
  map-coloration 
  and 
  

   signs 
  was 
  furnished 
  by 
  the 
  essays 
  sent 
  in 
  to 
  the 
  Congress 
  to 
  compete 
  

   for 
  the 
  prize 
  of 
  5000 
  francs 
  (.£200) 
  offered 
  by 
  the 
  King 
  of 
  Italy 
  for 
  

   the 
  best 
  memoir 
  on 
  these 
  subjects. 
  Although 
  not 
  one 
  of 
  the 
  papers 
  

   offered 
  was 
  deemed 
  worthy 
  of 
  the 
  full 
  prize, 
  three 
  received 
  awards 
  

   and 
  were 
  published 
  in 
  the 
  General 
  Report 
  of 
  the 
  Congress. 
  All 
  of 
  

  

  