478  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1905. 
Nebraska  the  beds  grow  coarse  and  heavy  toward  the  southwest,  and  he  suggests  that  the 
source  is  in  that  direction.  Scattered  deposits,  besides  those  in  Colorado,  Montana,  and 
Idaho,  above  mentioned,  have  also  been  found  in  Arizona  and  Nevada.  The  age  of  the 
deposits  in  the  various  States,  according  to  published  accounts,  is  not  the  same,  for  ash  bods 
occur  at  several  horizons  and  in  many  localities  contain  distinctive  fossils.  The  beds  have 
been  found  to  range  from  the  Oligocene  up  into  the  loess  of  the  Great  Plains.  In  the  Durango 
deposits,  however,  no  fossils  were  observed,  and  the  indications  of  age  are  limited  to  the 
relations  of  occurrence.  These  restrict  the  age  to  post-Cretaceous  and  probably  pre- 
Pleistocene.  The  nearest  known  deposit  bearing  fossils  is  in  Huerfano  County,  140  miles 
east  of  Durango.  Vertebrate  remains  discovered  there  by  R.  C.  Hills  have  been  referred 
to  the  Pliocene.  While  this  deposit  closely  resembles  the  Durango  beds  in  character  and  is 
but  a  short  distance  away,  its  geologic  relations  are  not  similar,  and  the  correlation  of  the 
two  occurrences  can  not  yet  be  made. 
Development  and  i;ses.— The  bed  north  of  Animas  City  Mountain  lias  been  prospected  by 
Mr.  Charles  Naegelin,  the  owner,  by  means  of  a  shaft  to  a  depth  of  12  feet  and  by  auger 
borings  several  feet  deeper.  He  has  made  no  attempt  to  prepare  the  material  for  market . 
He  was  formerly  owner  of  the  deposits  west  of  Junction  Creek,  which  he  sold  several  years 
ago  to  the  Lavaline  Company,  of  Durango.  This  company  has  opened  t  he  bed  by  a  surface 
excavation  10  feet  deep  and  20  feet  in  diameter.  The  ash  was  chuted  into  carts  and  hauled 
to  Durango,  where  it  was  put  up  in  packages  for  market  as  a  cleaner.  For  some  reason  the 
company  failed  and  ceased  operations,  and  now  the  property  is  abandoned.  The  bed  on 
Florida  Mesa,  owned  by  Mr.  Spencer,  was  opened  eight  or  ten  years  ago,  but  for  what  pur- 
pose is  unknown. 
Ash  of  this  sort  in  other  parts  of  the  West  was  used  by  early  settlers,  it  is  said,  as  a  plaster 
for  building  purposes,  but  it  crumbled  and  was  not  durable.  It  is  now  locally  used  in  many 
of  the  States  named  as  a  scouring  powder  and  is  put  up,  especially  in  Nebraska,  under  the 
names  "Nebraska  Silicate."  "Geyserite,"  "Gibson  Grit,"  "Diamond  Polish,"  etc.,  and  sold 
as  a  polishing  powder.  It  has  also  been  used  to  some  extent  in  the  manufacture  of  sand 
soaps  at  Denver  and  Omaha,  but  it  is  said  to  be  not  so  good  for  this  and  other  cleaning 
purposes  as  the  unpolled  article,  because  the  latter  is  made  of  particles  very  angular  and 
pointed,  whereas  the  domestic  material  consists  of  flat  glassy  scales. 
That  the  Durango  deposits  may  likewise  be  used  as  an  abrasive  for  many  purposes  is 
undoubted,  but  in  view  of  the  reports  that  in  Nebraska,  where  it  can  be  loaded  on  cars  at 
$2.50  to  $3  a  ton  and  where  freightage  is  low  ,  I  he  yearly  out  put  of  t  he  whole  State  does  not 
exceed  $5,000,  it  seems  that  the  Durango  deposits  are  chiefly  valuable  for  local  consumption. 
Of  the  many  uses  which  have  been  suggested  for  this  kind  of  ash  may  be  mentioned  semi- 
fused  filling  brick,  fireproofing,  and  mineral  wool  for  packing  as  a  nonconductor  of  heat  and 
sound.  It  might  also  be  used  in  its  natural  state  as  a  nonconductor  of  heat  in  refrigerating, 
and  there  seem-  no  reason  why  it  should  not  be  used  as  one  of  the  elements  in  the  manufac- 
ture of  puzzolan  cements,  and  perhaps  of  some  varieties  of  glassware. 
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Merrill,  G.  P.     Proceedings  United  States  National  Museum,  vol.  7,  1885,  pp.  99-100. 
Peale,  A.  C.     Lacusl  rine  deposits  of  Montana.     Science,  vol.  8.  1886,  pp.  163-165 
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