landes.]  CLAY    DEPOSITS    OF    WASHINGTON.  555 
from  sand.  Now  and  then  sand  and  gravel  appear,  but  ordinarily 
not  in  sufficient  amount  to  impair  the  quality  of  the  brick.  The 
extent  of  such  deposits  is  very  great,  and  at  the  more  favorable  locali- 
ties brick  industries  have  been  developed. 
Spokane  district. — At  Freeman,  in  the  southern  part  of  Spokane 
County,  several  clay  pits  have  been  opened  by  the  Washington  Brick, 
Lime,  and  Manufacturing  Company,  of  Spokane.  The  general 
classes  of  clays  are  found  here — a  clay  derived  from  basalt  and  one 
derived  from  granite  and  certain  associated  rocks.  Two  large  pits 
have  been  opened,  and  the  dividing  line  between  the  granite  area  on  the 
east  and  the  basalt  field  on  the  west  passes  between  the  two  clay  de- 
posits, so  that  both  kinds  of  clay  are  taken  out.  The  clay  above  the 
basalt  is  about  GO  feet  in  thickness,  the  upper  25  feet  only  being 
worked.  The  lower  part  of  the  clay  is  doubtless  of  residual  origin, 
but  the  upper  portion  has  clearly  been  blown  about  by  the  winds  and 
displays  an  eolian  character.  The  clay  is  of  a  deep  reddish-brown 
color,  and  much  of  it  is  distinctly  jointed.  It  contains  more  or  less 
grit  and  occasionally  thin  layers  of  sand  or  small  pebbles. 
The  adjacent  clay  pit  is  located  in  rocks  composed  primarily  of 
granite,  gneiss,  and  pegmatite  dikes,  with  some  mica-schist.  All 
these  rocks  have  been  profoundly  affected  by  weathering.  They  have 
been  made  so  soft  and  incoherent  that  they  may  easily  be  taken  out 
with  a  pick  and  shovel.  A  test  hole  to  the  depth  of  80  feet  showed 
the  rocks  to  be  of  the  same  nature  to  that  depth.  In  the  face  of 
the  quarry,  which  is  vertical  and  about  20  feet  high,  the  rocks  show 
that  they  have  suffered  no  displacement  as  a  result  of  weathering, 
occupying  perfectly  normal  positions.  The  very  marked  excess  of 
weathering  over  erosion  is  due  chiefly  to  the  fact  that  the  country  is 
comparativeh'  level  or  very  gently  rolling  and  the  annual  rainfall  is 
low.  Upon  the  walls  of  the  quarry  a  wonderful  array  of  brilliant 
colors  is  shown,  mainly  due  to  varying  degrees  of  oxidation.  The 
chief  colors  are  varying  shades  of  red,  with  yellows,  browns,  blues, 
and  pure  whites.  From  the  pegmatite  dikes,  which  are  rich  in  feld- 
spar, clays  of  good  quality  are  obtained,  but  the  materials  taken  from 
the  pit  are  scarcely  differentiated  in  use,  some  of  them  being  used  with 
the  clay  of  basaltic  origin  in  the  manufacture  of  common  brick,  while 
some  is  used  in  the  manufacture  of  fire  brick  and  fireproofing. 
At  Mica  are  extensive  deposits  of  clay  which  have  been  derived 
from  granite,  gneiss,  pegmatite,  schist,  etc.  These  deposits  lie  at  the 
foot  of  Mica  Mountain,  near  the  contact  of  the  granites  and  allied 
rocks  with  the  basalt  of  the  plain.  The  clay  beds  are  in  part  residual, 
but  under  the  influences  of  gravity  and  surface  wash  some  of  the 
clay  has  been  shifted  from  its  original  position  and  deposited  farther 
down  the  slope.     The  residual  clay  is  variegated  in  color,  and  ex- 
