38  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   1903.  [bull.  225. 
schist  between  the  black  slates  and  the  main  intrusive  mass  of  the 
Coast  Range,  and  these  intrusives  are  also  known  to  be  mineralized 
locally,  so  that  it  is  not  improbable  that  workable  deposits  may  jet  be 
discovered. 
On  the  seaward  side  of  the  slate-greenstone  contact  the  number  and 
importance  of  the  gold  veins  in  the  northern  belt  is  quite  as  great  as 
in  the  principal  lode  system.  In  this  region  the  bands  of  greenstone 
are  relatively  narrower  than  farther  south,  but  they  are  more  numerous, 
and  the  slate-greenstone  series  is  therefore  less  homogeneous.  The 
many  contacts  between  the  greenstone  beds  and  the  slates  are  fre- 
quently marked  by  veins  which  resemble  the  stringer  leads  of  the  main 
system,  though  they  are  not  traceable  through  the  same  distance. 
Many  of  them  are,  however,  well  marked  and  practically  continuous 
for  several  miles.  Besides  these,  there  are  also  many  veins  following 
well-defined  fissures  transverse  to  the  structure  of  the  rocks.  Such 
cross  veins  are  ordinarily  confined  to  massive  portions  of  the  green- 
stone beds  and  seldom.. if  ever,  cross  the  contacts  with  the  slates,  which 
are  not  massive,  and  therefore  ill  adapted  for  supporting  continuous 
fissures. 
Only  a  portion  of  the  slate-greenstone  band  occurs  north  of  Berners 
Bay,  the  upper  or  inland  portion  being  cut  out  by  masses  of  diorite. 
A  broad  band  of  this  intrusive  rock,  separated  from  the  main  mass 
which  forms  the  Coast  Range  by  a  narrow  band  of  slate  and  green- 
stone, is  present  south  of  the  bay,  and,  reappearing  on  the  north  side, 
cuts  diagonally  across  the  peninsula  between  Berners  Bay  and  Lynn 
Canal.  In  this  region  no  mineralization  has  been  discovered  in  the 
black  slates,  which  form  the  prevailing  rock  of  the  end  of  the  penin- 
sula. Most  of  the  veins  which  have  been  opened  within  the  drainage 
of  Johnson  Creek  and  Sherman  Creek  occur  in  the  outlying  band  of 
intrusive  diorites.  The  Jualin,  Comet,  Eureka,  Kensington,  and  other 
properties,  are  all  situated  in  this  formation,  most  of  them  on  veins 
which  fill  strong  fissures  belonging  to  two  systems.  The  Greek  Boy 
property,  however,  is  a  strong  stringer  lead,  which  occurs  in  the  slate 
belt  near  its  contact  with  the  main  diorite  at  the  head  of  Berners  Bay. 
The  combined  output  of  the  Berners  Bay  mines  to  date  is  estimated 
at  about  $1,100,000. 
The  Juneau  belt  can  not  be  definitely  recognized  beyond  the  Berners 
Bay  Peninsula,  which  it  crosses  diagonally  and  beyond  which  it  strikes 
into  Lynn  Canal.  Copper  deposits  which  are  reported  at  Sullivan 
Island,  near  the  west  side  of  the  canal,  nearly  opposite  Davidson 
Glacier,  may  represent  a  continuation  of  the  belt,  but  the  nature  of 
the  rocks  and  their  stratigraphic  position  relative  to  the  strata  of  the 
mainland  toward  the  southeast  is  not  known.  The  next  known  gold 
deposits  toward  the  northwest  are  in  the  Porcupine  district  of  the 
Chilkat  drainage,  50  miles  distant.  The  gravels  which  are  being  prof- 
itably worked  on  several  creeks  in  this  district  are  regarded  as  of  local 
