﻿Becker 
  — 
  Some 
  Queries 
  on 
  Bock 
  Differentiation. 
  37 
  

  

  this 
  way 
  and 
  only 
  a 
  rude 
  approximation 
  to 
  regularity 
  would 
  be 
  

   attained. 
  

  

  If 
  the 
  melted 
  masses 
  were 
  partially 
  or 
  wholly 
  miscible, 
  much 
  

   the 
  same 
  arrangement 
  would 
  take 
  place 
  at 
  first 
  because 
  diffu- 
  

   sion 
  on 
  any 
  large 
  scale 
  is 
  at 
  best 
  a 
  relatively 
  slow 
  process. 
  

   Then 
  diffusion 
  and 
  convection 
  would 
  come 
  in 
  play, 
  tending 
  to 
  

   equalize 
  the 
  composition. 
  

  

  On 
  the 
  other 
  hand, 
  unless 
  the 
  originally 
  heterogeneous 
  

   masses 
  had 
  very 
  different 
  properties 
  from 
  those 
  of 
  remelted 
  

   rocks, 
  whether 
  of 
  Algonkian 
  or 
  modern 
  time, 
  they 
  cannot 
  

   have 
  diffused 
  on 
  any 
  large 
  scale, 
  and 
  uniformity 
  along 
  equipo- 
  

   tential 
  surfaces 
  cannot 
  have 
  been 
  attained 
  even 
  if 
  fifty 
  million 
  

   years 
  were 
  allowed 
  for 
  the 
  process, 
  unless 
  the 
  convection 
  cur- 
  

   rents 
  were 
  so 
  powerful 
  and 
  universal 
  as 
  to 
  break 
  up 
  the 
  original 
  

   masses 
  into 
  streaks 
  of 
  a 
  few 
  meters 
  in 
  width. 
  I 
  see 
  no 
  cause 
  

   for 
  convection 
  so 
  active 
  as 
  this. 
  In 
  the 
  nebulous 
  state 
  the 
  

   material 
  of 
  the 
  earth 
  must 
  have 
  assumed 
  some 
  approach 
  to 
  

   convective 
  equilibrium 
  of 
  temperature, 
  and 
  though 
  here 
  and 
  

   there 
  the 
  solidifying 
  globe 
  may 
  have 
  been 
  affected 
  by 
  dis- 
  

   turbances 
  of 
  frightful 
  intensity, 
  analogous 
  to 
  sun 
  spots, 
  a 
  

   general 
  diversity 
  of 
  temperature 
  sufficient 
  to 
  stir 
  the 
  whole 
  or 
  

   most 
  of 
  the 
  melted 
  layer 
  into 
  uniformity 
  seems 
  utterly 
  

   improbable. 
  

  

  What 
  is 
  known 
  of 
  the 
  properties 
  of 
  matter 
  seems 
  to 
  me 
  to 
  

   point 
  to 
  the 
  hypothesis 
  that 
  the 
  material 
  of 
  the 
  earth 
  is 
  rudely 
  

   arranged 
  by 
  density 
  irrespective 
  of 
  chemical 
  composition, 
  the 
  

   different 
  masses 
  mingling 
  for 
  a 
  few 
  meters 
  or 
  scores 
  of 
  meters 
  

   along 
  their 
  common 
  boundaries, 
  this 
  structure 
  being 
  due 
  to 
  

   original 
  heterogeneity. 
  If 
  segregation 
  took 
  place 
  at 
  all, 
  prior 
  

   to 
  the 
  consolidation 
  of 
  such 
  a 
  globe, 
  this 
  process 
  would 
  be 
  lim- 
  

   ited 
  to 
  particular 
  masses 
  and 
  would 
  tend 
  to 
  still 
  greater 
  hetero- 
  

   geneity. 
  

  

  Hypogeal 
  refusion. 
  — 
  Consider 
  now 
  the 
  effect 
  of 
  the 
  refu- 
  

   sion 
  of 
  any 
  portion 
  of 
  the 
  earth's 
  mass. 
  Unless 
  the 
  tempera- 
  

   ture 
  of 
  the 
  magma 
  were 
  raised 
  essentially 
  above 
  the 
  initial 
  

   temperature 
  of 
  the 
  molten 
  globe, 
  or 
  unless 
  it 
  were 
  melted 
  at 
  a 
  

   very 
  different 
  pressure, 
  the 
  magma 
  would 
  simply 
  be 
  restored 
  to 
  

   the 
  condition 
  in 
  which 
  it 
  existed 
  before 
  the 
  primal 
  consolida- 
  

   tion. 
  There 
  is 
  no 
  indication 
  that 
  lavas 
  prior 
  to 
  eruption 
  are 
  

   really 
  raised 
  to 
  temperatures 
  greatly 
  above 
  that 
  of 
  fusion, 
  for 
  

   almost 
  all 
  of 
  them 
  bring 
  solid 
  phenocrysts 
  to 
  the 
  surface, 
  nor 
  

   is 
  it 
  easy 
  to 
  see 
  how 
  they 
  could 
  be 
  heated 
  much 
  above 
  the 
  

   melting 
  point, 
  for 
  so 
  long 
  as 
  there 
  was 
  unfused 
  material 
  of 
  a 
  

   similar 
  character 
  in 
  the 
  neighborhood 
  of 
  the 
  subterranean 
  mass 
  

   undergoing 
  fusion, 
  any 
  heat 
  increment 
  would 
  of 
  course 
  melt 
  

   more 
  rock 
  instead 
  of 
  raising 
  the 
  temperature 
  of 
  that 
  already 
  

   fused. 
  Thus 
  it 
  is 
  substantially 
  certain 
  that 
  in 
  the 
  molten 
  globe 
  

  

  