466  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1905. 
The  beH  of  Si  Peter  ("  Pacific")  sandstone  between  Klondike,  on  Missouri  River,  about 
40  miles  above  its  mouth,  and  Crystal  City,  on  the  Mississippi,  10  miles  below  St.  Louis,  eon- 
tains  the  principal  glass-sand  plants  of  the  State.  This  district  is  partially  covered  by  the 
Survey  topographic  maps  of  the  St.  Louis,  O'Fallon,  and  De  Soto  quadrangles.  The  rocks 
dip  slightly  to  the  northeast,  but  so  slightly  that  locally  they  may  be  regarded  as  being  hori- 
zontal.    The  outcrop  of  the  sandstone  in  this  region  is  from  one-hall"  mile  to  5  miles  wide. 
)n  the  southwest  the  sandstone  is  bounded  by  older  Ordovician  dolomite  and  chert ,  while 
to  the  east  it  passes  beneath  later  Ordovician  dolomite,  which  is  in  turn  overlain  by  Devonian 
and  Mississippian  limestone  and  shale.  Mississippian  and  later  strata  constitute  the  coun- 
try  rock  at  St.  Louis  and  beyond  the  river  in  Illinois,  where  they  pass  beneath  the  main 
areas  of  Pennsylvanian  coal-bearing  rocks. 
Klondih  .  Glass  sand  is  produced  at  Klondike,  on  the  north  side  of  Missouri  River  about 
10  miles  above  its  mouth.  The  base  of  the  St .  Peter  sandstone  here  is  SO  or  more  feel  above 
Missouri  River,  which  flows  close  to  the  base  of  the  bin  IF,  just  beyond  the  tracks  of  the  Mis- 
souri, Kansas  and  Texas  Railway.  The  sandstone  is  about  SO  feet  thick.  It  lies  on  an 
irregular  surface  of  cherty  magnesian  limestone  or  dolomite,  t  he  uncomformity  between  the 
two  formations  being  well  displayed  in  the  east  pit  of  the  quarry,  where  small  domes  of 
cherty  rock  extend  up  into  the  sandstone  and  coarse  sandstone  fills  the  hollows  in  the  lime- 
stone floor.  ( Jverlying  I  he  St  .  Peter  is  a  bed  of  soft  greenish  sand  and  clay  shale,  succeeded 
by  alternating  thin  beds  of  sandy  limestone,  oolitic  siliceous  bands,  clay  shale,  and  earthy 
limestone,  with  nunc  massive  magnesian  limestone  beds  above,  the  whole  cover  aggregat- 
ing about  30  feel  at  the  summit.  This  overlying  formation  has  been  termed  the  "  First 
Magnesian  "  limestone.  At  presenl  the  removal  of  this  overburden  is  a  dead  loss,  since  the 
rock  is  noi  considered  of  value  for  any  purpose. 
In  texture  the  sandstone  displays  the  well-known  St.  Peter  characteristics  of  well-j 
rounded,  medium-sized  grains  (see  table,  p.  156)  and  is  so  friable  as  to  be  easily  crushed. 
The  upper  25  to  .'!()  feet  are  slightly  colored  pink  or  brown  in  places.  Lower  down  it, 
becomes  pure  while  or  fain!  yellow.  No  marked  crOSS-bedding  is  noticeable  here,  but  in 
places  there  are  distinct  but  not  persistent  horizontal  bedding  planes.  Impurities  are  rare. 
Occasionally  a  small  -peck  or  "button*'  of  iron  oxide  is  encountered,  cementing  the  adja- 
cent  sand  grains  into  a  verj  hard  lump,  but  these  harder  masses  are  removed  in  screening. 
The  workings  of  the  Tavern  Pock  Sand  ( !ompany  at  Klondike  extend  about  one-fourth  mile 
along  the  face  of  the  bin  If.  The  sand  is  "shot"  down  and  gathered  by  means  of  tram  cars 
drawn  by  mule-  to  central  points  in  the  several  pit--,  where  the  cars  an-  picked  up  by  cable 
and  drawn  to  the  mill.  The  sand  is  dumped  direct  ly  into  crushers,  from  which  it  passes  to 
the  driers.  It  is  elevated  to  the  screens  and  then  falls  into  bins,  from  which  it  is  drawn  oil' 
into  railroad  cars  for  shipment .  There  are  twin  mills  built  on  the  terrace  capping  the  steep 
slope  between  the  railroad  t  rack  below  and  the  base  of  the  sandstone.  Each  mill  is  equipped 
with  Gate- gyratory  crusher-,  rotary-drum  driers,  elevators,  screens,  bins,  and  chutes.  The 
power  house  i-  on  the  river  bank  across  the  track  from  the  mill.  The  position  of  the  sand 
bed,  high  in  the  bluff,  is  of  advantage  in  many  ways.  The  quarries  are  easily  drained  and 
can  be  worked  to  the  full  thickness  of  the  sandstone.  While  difficulties  were  encountered 
in  the  erect  ion  of  the  mill  on  the  steep  face  of  the  bluff,  its  position  in  relation  to  the  sand- 
stone is  of  advantage,  for  gravity  is  made  to  play  a  large  part  in  the  process  of  handling  the 
sand  from  the  quarry  to  the  railroad  cars.  The  topography  of  the  tract  being  worked  by 
this  company  favors  long  continuance  of  the  industry.  When  stripping  of  the  beds  over- 
lying the  sandstone  has  been  carried  as  far  as  praet  icable  on  the  river  front ,  quarrying  may 
be  begun  on  the  north  side  of  the  narrow  divide  which  lies  between  the  river  and  the  small 
ravine  parallel  to  ii .  about  one-fourth  mile  to  the  north.  After  considerable  quarrying  has 
been  done  on  the  north  side  the  thickest  limestone  cover  in  the  middle  of  the  ridge  may  be 
economically  stripped  back  into  the  north  quarry,  making  available  the  whole  block  of 
sandstone  constituting  the  ridge  back  of  Klondike  and  extending  nearly  one-half  mile  east. 
