﻿W, 
  D. 
  MacMillan 
  — 
  Mathematics 
  of 
  Isostasy. 
  323 
  

  

  concrete 
  physical 
  or 
  natural 
  criteria 
  to 
  which 
  appeal 
  

   must 
  be 
  made 
  to 
  distinguish 
  the 
  solution 
  that 
  actually 
  

   applies 
  to 
  the 
  real 
  case 
  from 
  the 
  solutions 
  that 
  merely 
  

   fit 
  the 
  terms 
  of 
  the 
  data 
  mathematically. 
  

  

  I 
  pass 
  by 
  many 
  minor 
  points 
  of 
  criticism 
  because 
  they 
  

   are 
  of 
  little 
  moment 
  in 
  themselves 
  and 
  I 
  desire 
  to 
  limit 
  

   my 
  reply 
  to 
  such 
  fundamental 
  matters 
  as 
  are 
  too 
  vital 
  

   to 
  the 
  wholesome 
  progress 
  of 
  science 
  to 
  be 
  passed 
  in 
  

   silence, 
  much 
  as 
  I 
  regret 
  the 
  necessity 
  of 
  any 
  reply 
  at 
  all. 
  

   In 
  my 
  judgment 
  there 
  are 
  few 
  things 
  more 
  prejudicial 
  

   to 
  the 
  progress 
  of 
  science 
  than 
  the 
  unwarranted 
  assump- 
  

   tion 
  that 
  a 
  far-reaching 
  doctrine 
  is 
  proved, 
  while 
  yet 
  real 
  

   proof 
  is 
  far 
  from 
  having 
  been 
  reached 
  and 
  may 
  be 
  quite 
  

   unattainable 
  in 
  any 
  strict 
  sense. 
  I 
  think 
  that 
  an 
  intelli- 
  

   gent 
  belief 
  or 
  even 
  a 
  favorable 
  impression, 
  entertained 
  

   in 
  full 
  consciousness 
  that 
  demonstration 
  is 
  still 
  lacking, 
  

   is 
  a 
  better 
  support 
  for 
  a 
  doctrine 
  than 
  stronger 
  claims 
  

   on 
  a 
  less 
  secure 
  basis. 
  

  

  Aet. 
  XXIV. 
  — 
  Notes 
  on 
  the 
  Manzano 
  Group, 
  New 
  Mex- 
  

   ico; 
  by 
  Willis 
  T. 
  Lee. 
  1 
  

  

  These 
  notes 
  are 
  in 
  the 
  nature 
  of 
  a 
  review 
  of 
  two 
  papers 
  

   published 
  recently 
  in 
  this 
  Journal 
  as 
  follows 
  : 
  ' 
  i 
  Contri- 
  

   butions 
  to 
  the 
  Stratigraphy 
  of 
  Eastern 
  New 
  Mexico," 
  by 
  

   Charles 
  Lawrence 
  Baker 
  (Feb., 
  1920, 
  pp. 
  99-126), 
  and, 
  

   "On 
  the 
  Ammonoids 
  from 
  the 
  Abo 
  Sandstone 
  of 
  New 
  

   Mexico 
  and 
  the 
  Age 
  of 
  the 
  Beds 
  which 
  contain 
  them," 
  

   by 
  Dr. 
  Emil 
  Bose 
  (Jan., 
  1920, 
  pp. 
  51-60). 
  

  

  The 
  two 
  papers 
  deal 
  with 
  the 
  same 
  questions, 
  hence 
  

   should 
  be 
  considered 
  together. 
  The 
  contribution 
  by 
  

   Bose 
  deals 
  with 
  the 
  validity 
  of 
  the 
  previously 
  accepted 
  

   grouping 
  of 
  the 
  formations 
  and 
  with 
  the 
  establishment 
  

   of 
  the 
  Pennsylvanian-Permian 
  boundary 
  in 
  New 
  Mexico 
  ; 
  

   that 
  by 
  Baker 
  deals 
  with 
  these 
  and 
  several 
  other 
  prob- 
  

   lems 
  of 
  interest 
  to 
  those 
  concerned 
  with 
  the 
  stratigraphy 
  

   of 
  this 
  state. 
  

  

  Many 
  geologists 
  have 
  been 
  working 
  in 
  New 
  Mexico 
  in 
  

   recent 
  years 
  and, 
  although 
  much 
  of 
  the 
  available 
  infor- 
  

   mation 
  is 
  not 
  yet 
  published, 
  several 
  short 
  papers 
  have 
  

   appeared 
  bearing 
  on 
  one 
  or 
  another 
  of 
  the 
  problems. 
  

  

  1 
  Published 
  by 
  permission 
  of 
  the 
  Director 
  of 
  the 
  United 
  States 
  Geological 
  

   Survey. 
  

  

  