KAOLINS    AND    FIRE    CLAYS    OF    CENTRAL    GEORGIA. 
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bedded  quartz  and  mica  sand,  gravel,  and  white  clay.  The  lower 
member  of  the  eastern  belt,  or  that  part  east  of  Macon  and  the  Ocmul- 
gee  River,  consists  of  coarse,  clayey  gravel  and  sand,  which  near  the 
contact  with  the  crystalline  rocks  is  locally  an  arkose  and  is  at  many 
places  indurated.  The  clayey  sand  is  generally  cross  bedded  and  has 
a  characteristic  pink  color.  It  contains  lenses  of  kaolin  of  remarkable 
purity,  but  most  of  these  are  of  small  extent,  and  the  kaolin  of  which 
they  are  formed  is  likely  to  vary  in  texture  or  to  grade  into  sand  within 
a  short  distance.  The  upper  member  of  the  Tuscaloosa,  in  the 
eastern  belt,  is  composed  largely  of  clay  in  beds  10  to  35  feet  thick, 
which  is  exposed  at  various  places  throughout  a  distance  of  approxi- 
mately 90  miles.  These  clays  vary  from  pure  white  and  cream- 
colored  gritless  kaolins  to  semihard  and  flint  fire  clays.     The  clays  of 
Fig.  10. — Map  showing  exposures  of  Cretaceous  roeks  in  Georgia. 
this  formation  are  for  the  most  part  white  or  light  colored,  but  in 
places  may  be  mottled  red,  yellow,  or  purple  by  iron  pxide.  The  for- 
mation is  largely  obscured  by  overlying  deposits  of  Eocene  sands  and 
clays,  exposures  of  clay  occurring  only  where  stream  erosion  has 
removed  the  overlying  strata  and  in  artificial  cuts.  The  beds  vary  in 
thickness  and  are  associated  with  more  or  less  kaolinic  sand.  The 
thickness  of  the  Tuscaloosa  of  eastern  central  Georgia  varies  from  50 
to  500  feet. 
The  western  belt  of  the  Tuscaloosa,  or  that  part  lying  between 
Macon  and  Columbus,  is  for  the  most  part  similar  lithologically  to  the 
eastern  belt.  The  subdivision  of  the  eastern  belt  of  the  Tuscaloosa 
into  an  upper  and  lower  member  will  probably  not  hold  for  that  part 
