440         CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   L906,   PART    I. 
LOCALITIES   OF  DIATOMACEOUS  DEPOSITS. 
REGION    SOUTH    OF    SANTA    5TNEZ    RIVER. 
South  of  Lompoc.  The  only  deposits  of  diatomaceous  earth  in 
northern  Santa  Barbara  County  that  have1  been  put  to  use  occur 
just  south  of  Lompoc,  in  the  foothills  of  the  Santa  Ynez  Range,  east 
of  the  canyon  of  San  Miguelito  Creek.  From  the  edge  of  the  hills  at 
Lompoc  for  a  distance  of  2  miles  or  more  to  the  south  the  hills  are 
formed  of  soft  white  diatomaceous  earth  in  a  very  pure  state.  It  is  j 
directly  at  the  surface,  can  he  quarried  with  the  utmost  ease,  and  is 
ready  for  shipment  on  removal  from  the  quarry.  In  some  places 
the  material  is  in  great  soft  masses,  in  which  the  bedding  can  not  he 
recognized  except  by  the  characteristic  weathering  into  flaky  layers 
parallel  with  the  original  bedding  planes.  Elsewhere  it  is  more  com! 
pact  and  in  thin  beds  varying  from  half  an  inch  to  2  or  3  inches  in 
thickness  or  in  massive  beds.  The  beds  are  tilted  and  in  conformity 
with  the  much-disturbed  hard  beds  (A'  flinty  shale  of  the  lower  por- 
tion of  the  Monterey  formation,  of  which  the  whole  series  is  a  part. 
In  places  the  diatomaceous,  earthy  horizon  is  traversed  by  thin 
laminae  o['  hard  brown  brittle  shale.  There  must  he  at  least  -'5  squard 
miles  over  which  the  diatomaceous  shale  is  exposed,  and  the  thick! 
[less  in  some  places  reaches  several  hundred  feet. 
It  may  he  mentioned  in  passing  that  some  thin  deposits  of  vol-| 
canic  ash,  comprising  over  the  whole  area  a  large  amount  of  material] 
are  iuterhedded  with  the  diatomaceous  earth  in  this  region.  The 
ash  is  of  a  siliceous  variety,  probably  corresponding  in  composition 
to  an  acidic  lavalike  rhyolite.  It  is  soft,  pulverulent,  of  a  lustrous 
grayish  color,  slightly  more  gritty  than  the  tripoli,  and  x^ix  homo-] 
geneous.  It>  somewhat  coarser  nature  might  make  il  valuable  for 
io  which  the  diatomaceous  earth  is  unsuited.  It  is  worthy  of 
note  that  large  quantities  of  volcanic  ash  under  the  designation  of 
pumice  are  imported  annually  from  the  Lipari  Islands,  in  Italy,  for 
use  ;i>  abrasive  material. 
Two  quarries  are  in  active  operation  at  Lompoc,  that  of  Balaam] 
Brothers  and  that  of  the  Magne-Silica  Company,  <>f  Los  AngelesI 
and  considerable  quantities  of  the  diatomaceous  earth  are  shipped 
to  Los  Angeles  and  elsewhere.  Active  preparations  are  being  made 
for  the  installation  of  a  plant  at  Lompoc  for  the  treatment  of  the 
earth. 
Southwest  and  west  oj  Lompoc. — The  outer  portion  of  the  hills 
southwest  of  Lompoc,  along  the  southern  border  of  the  Lompoc 
Valley,  is  composed  of  soft  white  diatomaceous  shale  that  is  tho 
westward  continuation  of  the  deposit  just  noted.  It  is  of  greal 
purity  and  of  such  extent  and  thickness  that  it  will  afford  an  almost 
unlimited  field  for  development.     It  would  be  difficult  to  estimate  j 
