﻿Geology 
  and 
  Natural 
  History. 
  79 
  

  

  4. 
  Notes 
  on 
  the 
  geology 
  of 
  the 
  Glass 
  Mountains; 
  by 
  J. 
  A. 
  

   TJdden, 
  and 
  Geologic 
  exploration 
  of 
  the 
  southeastern 
  Front 
  

   Range 
  of 
  Trans-Pecos 
  Texas; 
  by 
  C. 
  L. 
  Baker 
  and 
  W. 
  F. 
  

   Bowman. 
  Univ. 
  of 
  Texas 
  Bull. 
  No. 
  1753, 
  177 
  pp., 
  12 
  pis., 
  1 
  

   map, 
  Sept. 
  20, 
  1917 
  [July 
  1918] 
  .—During 
  the 
  past 
  several 
  years, 
  

   evidence 
  has 
  been 
  coming 
  forward 
  that 
  there 
  is 
  a 
  distinct 
  and 
  

   clearly 
  separable 
  Permian 
  system 
  in 
  America, 
  with 
  the 
  clearest 
  

   testimony 
  in 
  the 
  southwestern 
  portion 
  of 
  the 
  United 
  States. 
  In 
  

   this 
  report 
  are 
  described 
  the 
  many 
  formations, 
  along 
  with 
  their 
  

   structure, 
  that 
  compose 
  the 
  Pennsylvanian 
  and 
  Permian 
  systems 
  

   of 
  the 
  Trans-Pecos 
  area 
  of 
  Texas. 
  Baker 
  and 
  Bowman 
  also 
  

   point 
  out 
  a 
  time 
  of 
  mountain 
  making, 
  one 
  in 
  the 
  midst 
  of 
  the 
  

   rock 
  sequence, 
  that 
  seemingly 
  will 
  divide 
  the 
  series 
  into 
  two 
  

   systems, 
  the 
  Pennsylvanian 
  with 
  a 
  thickness 
  here 
  of 
  about 
  4800 
  

   feet 
  and 
  the 
  Permian 
  with 
  9640 
  feet 
  of 
  strata. 
  It 
  is 
  further 
  

   interesting 
  to 
  note 
  that 
  in 
  this 
  series 
  of 
  strata 
  there 
  are 
  many 
  

   species 
  of 
  new 
  ammonids 
  that 
  will 
  soon 
  be 
  described 
  by 
  Doctor 
  

   E. 
  Boese. 
  c. 
  s. 
  

  

  5. 
  The 
  geology 
  of 
  Vancouver 
  and 
  vicinity; 
  by 
  Edward 
  

   Moore 
  Jackson 
  Burwash. 
  Pp. 
  106, 
  24 
  text 
  figs., 
  3 
  maps, 
  

   Chicago, 
  1918 
  (University 
  of 
  Chicago 
  Press, 
  $1.50). 
  — 
  In 
  this 
  

   valuable 
  publication 
  are 
  described 
  the 
  geography, 
  physiography, 
  

   and 
  geology 
  of 
  an 
  area 
  of 
  about 
  70 
  by 
  80 
  miles 
  around 
  the 
  city 
  

   of 
  Vancouver, 
  British 
  Columbia. 
  Much 
  attention 
  is 
  given 
  to 
  the 
  

   igneous 
  masses 
  and 
  their 
  effect 
  as 
  miner 
  alizers 
  upon 
  the 
  rocks 
  

   intruded. 
  The 
  work 
  is 
  profusely 
  illustrated. 
  c. 
  s. 
  

  

  6. 
  Geology 
  of 
  the 
  northern 
  end 
  of 
  the 
  Tampico 
  embayment 
  

   area; 
  by 
  E. 
  T. 
  Dumble. 
  Proc. 
  Calif. 
  Acad. 
  Sci., 
  4th 
  ser., 
  8, 
  No. 
  

   4, 
  pp. 
  113-156, 
  pis. 
  3-6, 
  1918.— 
  Since 
  1890, 
  northwestern 
  Mexico 
  

   has 
  been 
  a 
  field 
  much 
  exploited 
  for 
  petroleum. 
  Due 
  to 
  the 
  work 
  

   of 
  the 
  author 
  and 
  others, 
  the 
  geology 
  of 
  this 
  area 
  is 
  now 
  well 
  

   known 
  in 
  its 
  broader 
  outlines, 
  and 
  it 
  is 
  here 
  described. 
  The 
  

   formations 
  treated 
  are 
  those 
  of 
  late 
  Mesozoic 
  and 
  Cenozoic 
  times. 
  

  

  c. 
  s. 
  

  

  7. 
  Bidrag 
  til 
  Finmarkens 
  geologi; 
  by 
  Olaf 
  Holtedahl. 
  

   Norges 
  Geol. 
  Unders., 
  No. 
  84, 
  314 
  pp., 
  21 
  pis., 
  38 
  text 
  figs., 
  2 
  

   geological 
  maps, 
  1918. 
  — 
  In 
  this 
  book 
  the 
  author 
  describes 
  the 
  

   geology 
  of 
  the 
  most 
  northern 
  district 
  of 
  Norway, 
  and 
  on 
  pages 
  

   299-314 
  the 
  information 
  is 
  presented 
  in 
  condensed 
  form 
  in 
  Eng- 
  

   lish. 
  Dahll's 
  Gaisa 
  system 
  is 
  abandoned, 
  as 
  it 
  contains 
  "the 
  

   most 
  heterogeneous 
  things," 
  while 
  the 
  Eaipas 
  has 
  been 
  much 
  

   restricted. 
  To 
  the 
  south 
  is 
  the 
  old 
  pre-Cambrian 
  nucleus 
  and 
  

   upon 
  its 
  ancient 
  peneplaned 
  surface 
  was 
  laid 
  down 
  the 
  marine 
  

   Lower 
  Cambrian. 
  These 
  strata, 
  230 
  meters 
  thick, 
  are 
  still 
  gener- 
  

   ally 
  unfolded, 
  and 
  also 
  the 
  later 
  Ordovician 
  sandstones, 
  which 
  

   are 
  over 
  2000 
  m. 
  thick 
  and 
  are 
  followed 
  by 
  more 
  than 
  4000 
  m. 
  of 
  

   dolomites. 
  At 
  a 
  later 
  date 
  came 
  the 
  great 
  Caledonian 
  over- 
  

   thrusts. 
  The 
  tillites 
  described 
  by 
  Keusch 
  in 
  1890 
  and 
  generally 
  

   assumed 
  to 
  be 
  of 
  Cambrian 
  age 
  are 
  shown 
  by 
  Holtedahl 
  to 
  be 
  

  

  