16  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  VA)(>,  PART    I. 
mining  district,  and  the  loss  of  trained  men  in  this  work  is,  for  a 
time,  irreparable.  Since  the  force  available  has  been  thus  greatlj 
reduced,  the  field  work  carried  on  during  the  last  season  has  been 
vvi'v  largely  in  the  nature  of  reconnaissance  work  and  lias  been  con- 
lined  to  the  Rocky  Mountain  region.  It  will  be  described,  as  here- 
tofore, by  States  and  Territories. 
ARIZONA. 
In  Arizona  Mr.  Etansome  commenced  in  October  a  special  study  of 
the  Tombstone  district,  a  once  famous  silver  district  that  lias  been 
reopened  in  the  last  few  years  after  a  long  period  of  idleness.  By 
the  end  i>(  the  month  he  had  completed  a  preliminary  reconnaissance 
of  the  district  and  stalled  for  Nevada,  where1  there  is  an  overwhelm! 
ing  demand  for  geological  examinations  of  many  new  districts  that 
are  constantly  springing  into  existence:  hut  while  examining  a 
geological  section  on  the  walls  of  the  Grand  Canyon  of  Colorado 
River  the  drum  of  his  ear  was  accidentally  punctured  by  a  twig] 
What  was  first  thought  to  he  a  trivial  injury  proved  later  to  be  so 
serious  that  he  was  obliged  to  submit  to  a  surgical  operation  and 
spent  several  months  in  a  hospital,  where  he  still  remains,  incapaci- 
tated for  work. 
CALIFORNIA. 
In  California  L.  G.  Graton  has  been  occupied  during  the  summer 
in  a  special  and  detailed  study  of  several  important  copper  districts 
on  both  sides  of  the  Sacramento  Valley  in  Shasta  County.  These 
occur  in  the  highly  metamorphosed  rocks  that  characterize  the  west- 
ern slope  of  the  Sierra  Nevada  and  present  a  highly  intricate  geologi-j 
cal  problem.  During  a  rather  short  held  season  he  has  been  able  to 
complete  the  study  of  only  one  of  these  areas  the  Bully  Hill  dis- 
trict ;i  report  on  which  will  he  prepared  for  publication  during  the 
present  office  season.  Work  on  the  other  districts  will  he  resumed 
in  the  coming  summer.  Owing  to  the  pressure  of  his  other-  work, 
Mr.  Graton  has  been  unable  to  prepare  an  abstract  of  this  report  for! 
the  present  bulletin. 
COLORADO. 
In  the  San  Juan  region,  as  an  adjunct  to  the  work  being  carried  on 
under  Whit  man  Cross,  L.  Ii.  Woolsey  made  a  reconnaissance  exami- 
nation of  mines  in  the  Lake  Fork  quadrangle,  whose4  deposits  con- 
stitute the  eastern  continuation  of  those  in  the  Silverton  quadrangle^ 
already  described. 
In  Boulder  County,  near  the  mining  town  of  Eldora,  Wnldemar 
Lindgren  made  an  examination  of  an  interesting  group  of  thin  veins 
