adams]  BABBIT    HOLE    SULPHUR   MINES,  NEVADA.  499 
little  evidence  of  bedding  in  the  sulphur  pits  and  mines.  The  rocks 
have  apparently  been  leached  by  hot  waters,  and  the  excavations  are 
made  in  loose,  siliceous  material  which  has  a  harsh  feeling  and  con- 
tains considerable  pulverulent  matter.  At  the  mouth  of  a  dry  water- 
course leading-  from  the  mines  to  the  border  of  the  desert  the  beds  are 
stratified  in  regular  nearly  horizontal  layers.  The  brecciated  material 
is  cemented  into  quartzite-like  beds.  In  another  watercourse,  about 
half  a  mile  southwest  of  the  mines,  there  are  exposures  of  variously 
colored  beds  of  tuffs  and  crumbling  material.  Rocks  of  the  same 
nature  as  those  found  at  the  sulphur  mines  occur  in  a  belt  running 
parallel  with  the  border  of  the  desert  for  a  distance  of  2  or  3  miles. 
Numerous  pits  that  have  been  dug  in  the  search  for  sulphur  serve  to 
expose  the  formation,  which,  on  account  of  the  large  amount  of 
detrital  material  on  the  slopes  of  the  mountains,  would  otherwise  be 
concealed. 
Mode  of  occurrence  of  the  sulphur. — The  sulphur  is  obtained  from 
open  pits,  tunnels,  and  underground  chambers.  In  many  cases  the 
sulphur  may  be  seen  from  the  surface  workings.  In  its  more  beautiful 
form  it  occurs  as  masses  of  crystals  depending  from  the  walls  of  irreg- 
ular cavities  and  incrusting  free  surfaces.  It  has  the  beautiful  yellow 
color  of  crystallized  sulphur,  with  here  and  there  a  reddish  tinge  due 
to  the  occurrence  of  a  small  amount  of  cinnabar  deposited  on  its  sur- 
face. The  most  important  mass  of  sulphur  found  is,  however,  of  a 
different  type.  It  is  seen  in  large  underground  chambers,  and  has  the 
appearance  of  a  flow  of  molten  sulphur  which,  welling  up,  has  filled 
open  channels  in  the  rocks.  It  contains  occasional  fragments  of  rocks, 
but  is  remarkably  pure.     Its  color  is  a  dark  resinous  yellow. 
Origin  of  the  sulphur. — It  is  probable  that  the  sulphur  at  the  Rabbit 
Hole  mines  has  been  derived  from  a  greath  depth  and  deposited  as  a 
result  of  solfataric  action.  It  may  have  had  as  its  source  a  molten 
magma,  from  which  it  ascended  in  the  form  of  vapor,  and  cooled  in 
the  fissures  and  interspaces  of  the  rocks  near  the  surface.  Portions 
of  the  deposit  appear  to  have  flowed  into  channels  and  cavities  in  the 
rocks  in  liquid  form. 
Sulphur  gases  may  have  accompanied  ascending  waters.  The  con- 
dition of  the  country  rock  indicates  that  it  has  been  subject  to  the 
action  of  thermal  waters,  since  in  certain  places  it  has  a  leached 
appearance  and  in  others  it  is  cemented  with  siliceous  material.  The 
existence  of  hot  springs  in  Nevada  at  the  present  time,  and  especially 
in  former  periods,  is  well  known.  Perhaps  the  most  familiar  hot 
springs  locality  is  Steamboat  Springs,  where  hot  water  is  now  issuing 
from  a  mass  of  siliceous  sinter  which  has  been  built  up  by  the  springs. 
There  are  masses  of  siliceous  sinter  attesting  the  former  action  of  hot 
waters  at  a  number  of  places  in  northwestern  Nevada,  and  just  south 
of  Humboldt  House  there  are  minor  occurrences  of  sulphur  in  the 
craters  of  extinct  hot  springs.     If  a  deposit  of  siliceous  sinter  was 
