FOR    THE    YEARS   1901-1905,   INCLUSIVE.  193 
Keyes  (Charles  Rollin) — Continued. 
18.  Depositional  equivalent  of  hiatus  at  base  of  our  Coal  Measures;  and  the  Arkansan 
series,  a  new  terrane  of  the  Carboniferous  in  the  western  interior  basin. 
Iowa  Acad.  Sei.,  Proc,  vol.  8,  pp.  119-128,  2  figs.,  1901. 
Discusses  evidences  of  denudation  prior  to  the  deposition  of  the  Coal  Measures  in  this  area, 
gives  tables  comparing  the  thickness  of  Coal  Measures  formations,  and  describes  the 
Arkansan  series. 
19.  Names  of  coals  west  of  the  Mississippi  River. 
Iowa  Acad.  Sci.,  Proc,  vol.  8,  pp.  128-137,  1901. 
Discusses  the  Carboniferous  deposits  of  the  western  interior  coal  field,  tabulates  the  terranes 
and  percentage  of  coal  production  of  each,  and  gives  a  list  of  names  that  have  been  applied 
to  the  coal  seams,  with  place  of  publication  and  stratigraphic  position. 
20.  Diverse  origins  and  diverse  times  of  formation  of  the  lead  and  zinc  deposits  of 
the  Mississippi  Valley. 
Am.  Inst.  Mg.  Engrs.  Trans.,  vol.  31,  pp.  603-611,  1902. 
Discusses  mode  of  formation  of  these  ores. 
21.  [In  discussion  of  "  The  origin  of  ore-deposits."] 
Am.  Inst.  Mg.  Engrs.,  Trans.,  vol.  31,  pp.  942-944,  962-966,  1902. 
22.  Character  and  stratigraphical  peculiarities  of  the  southwestern  Iowa  coal  fields. 
Eng.  &  Mg.  Jour.,  vol.  73,  p.  661,  1902. 
Describes  the  stratigraphic  position  of  these  coals. 
23.  Determination  of  the  Cambrian  age  [of]  the  magnesian  limestones  of  Missouri. 
Am.  Geol.,  vol.  29,  pp.  384-387,  1902. 
Reviews  previous  determinations  of  the  age  of  these  limestones. 
24.  Geological  age  of  certain  gypsum  deposits. 
Am.  Geol.,  vol.  30,  pp.  99-102,  1902. 
Discusses  the  evidences  of  the  age  of  the  Kansas  and  Iowa  gypsum  beds. 
25.  Cartographic  representation  of  geological  formations. 
Jour.  Geol.,  vol.  10,  pp.  691-699,  2  figs.,  1902. 
Discusses  the  criteria  by  which  formations  are  discriminated  and  the  methods  of  their  carto- 
graphic representation. 
26.  Devonian  interval  in  Missouri. 
GeoL  Soc.  Am.,  Bull.,  vol.  13,  pp.  267-292,  1  pi.,  1902. 
Discusses  lithologic  and  faunal  characters  of  the  strata  and  the  evidence  of  unconformities. 
27.  Magmatic  differentiation  of  rocks. 
Science,  new  ser.,  vol.  15,  pp.  32-33,  1902. 
Discusses  the  formation  of  the  Magnet  Cove  [Arkansas]  igneous  mass  and  the  classification  of 
rocks. 
28.  A  Devonian   hiatus  in  the  continental  interior — its  character  and  depositional 
equivalents. 
Iowa  Acad.  Sci.,  Proc,  vol.  9,  pp.  10.5-112,  1902. 
Discusses  the  absence  of  Devonian  strata  in  west  central  Missouri  and  the  history  and  mean- 
ing of  the  terms  Kinderhook  and  Chouteau. 
29.  Geological  structure  of  New  Mexican  bolson  plains. 
Am.  Jour.  Sci.,  4th  ser.,  vol.  15,  pp.  207-210,  3  figs.,  1903. 
Describes  the  characters  of  these  plains  and  the  geologic  history  of  the  region. 
30.  Ephemeral  lakes  in  arid  regions. 
Am.  Jour.  Sci.,  4th  ser.,  vol.  16,  pp.  377-378,  1903. 
31.  Some  recent  aspects  of  the  Permian  question  in  America. 
Am.  Geol.,  vol.  32,  pp.  218-223,  1903. 
Discusses  questions  of  nomenclature  and  taxonomic  rank. 
32.  A  remarkable  silver  pipe. 
Eng.  &  Mg.  Jour.,  vol.  76,  p.  805,  1903. 
Discusses  the  occurrence  and  origin  of  "  pipe- veins,"  and  an  occurrence  in  central  New 
Mexico. 
Bull.  301—06 13 
