80  BIBLIOGRAPHY    OF    NORTH    AMERICAN    GEOLOGY 
Cross  (Whitman),  Iddings  (Joseph  P.),  Pirsson  (Louis  V.),  and  "Washing-ton 
(Henry  S.)- 
1.  A  quantitative  chemico-mineralogical  classification  and  nomenclature  of  igneous 
rocks. 
Jour.  Geol.,  vol.  10,  pp.  555-690,  1902. 
Gives  a  general  summary  of  the  new  system  and  describes  the  classification  and  nomencla- 
ture proposed.  Includes  chemical  analyses  and  tables  of  alferic  minerals  and  the  rocks  in 
which  they  occur. 
2.  Quantitative  classification  of  igneous  rocks  based  on  chemical  and  mineral  char- 
acters, with  a  systematic  nomenclature. 
University  of  Chicago  Press,  286  pp.,  1903. 
A  review  of  the  development  of  systematic  petrography  in  the  nineteenth  century,  by  Whit- 
man Cross,  is  followed  by  a  discussion  of  the  principles  of  classification  of  igneous  rocks 
and  an  exposition  of  the  new  system  of  classification  and  nomenclature  proposed  by  the 
authors  and  methods  of  calculation  for  determining  the  position  of  a  rock  in  their  system 
of  classification. 
Cross  (Whitman),  assisted  by  Arthur  Coe  Spencer. 
1.  General  geology,  La  Plata  folio,  Colorado. 
U.  S.  Geol.  Surv.,  Geol.  Atlas  of  U.  S.,  folio  no.  60,  1899. 
Describes  the  geographic  and  physiographic  features,  the  character  and  occurrence  of  the 
Juratrias,  Cretaceous,  Eocene,  and  Pleistocene  strata  and  igneous  rocks,  and  the  geological 
structure.    Includes  a  statement  of  the  general  geologic  problems  of  the  region. 
Crowther  (Henry  M.). 
1.  The  copper  deposits  of  the  Beaver  River  Range,  Utah. 
Eng.  &  Mg.  Jour.,  vol.  75,  p.  965,  1903. 
Describes  the  geologic  structure  and  the  occurrence  of  the  ores. 
Culbert  (M.  T.). 
1.  The  iron  belt  west  of  Hutton  [Ontario]. 
Ont.  Bur.  Mines,  Rept.,  1904,  pt.  1,  pp.  222-224,  4  pis.,  1904. 
Gives  observations  upon  the  geology  of  the  region  traversed  and  the  occurrence  of  iron  ores 
Culbertson  (Glenn). 
1.  Ripple  marks  in  Hudson  limestone  of  Jefferson  County,  Indiana. 
Ind.  Acad.  ScL,  Proc,  1902,  pp.  202-205,  1903. 
Cuming-s  (Edgar  Roscoe). 
1.  The  use  of  Bedford  as  a  formational  name. 
Jour.  Geol.,  vol.  9,  pp.  232-233,  1901. 
Proposes  the  name  Salem  limestone  for  the  Bedford  limestone,  the  latter  having  been 
preoccupied. 
2.  Orthothetes  minutus,  n.  sp.  from  the  Salem  limestone  of  Harrodsburg,  Indiana. 
Am.  Geol.,  vol.  27,  pp.  147-149,  1  pi.,  1901. 
3.  A  section  of  the  upper  Ordovician  at  Vevay,  Indiana. 
Am.  Geol.,  vol.  28,  pp.  361-380,  2  pis.,  1901. 
Gives  a  detailed  section,  names  the  fossils  found  in  each  bed,  and  compares  this  section  with 
that  at  Cincinnati.     Describes  four  new  species. 
4.  Notes  on  the  Ordovician  rocks  of  southern  Indiana. 
*Ind.  Acad.  Sci.,  Proc.  for  1900,  pp.  200-215,  1901. 
Gives  section  at  various  localities  with  notes  on  the  faunas. 
5.  Some  developmental  stages  of  Orthothetes  minutus  n.  sp. 
Ind.  Acad.  Sci.,  Proc.  for  1900,  pp.  216-218,  1901. 
6.  Lower  Silurian  system  of  eastern  Montgomery  County,  New  York. 
N.  Y.  State  Mus.,  Bull.,  no.  34  [also  in  54th  Ann.  Rept.,  vol.  1].  pp.  418-468,  4  pis.,  1  fig.,  5  cross 
sections,  geol.  map,  1902. 
7.  A  revision  of  the  Bryozoan  genera  Dekayia,  Dekayella,  and  Heterotrypa  of  the 
Cincinnati  group. 
Am.  Geol.,  vol.  29,  pp.  197-218,  4  pis.,  1902. 
Reviews  the  literature  on  these  genera  and  describes  new  species. 
