CLAYS  OF  WESTERN  KENTUCKY  AND  TENNESSEE. 
By  A.  F.  Crider. 
INTRODUCTION. 
| During  September  and  October,  1905,  the  writer  was  engaged  in  studying  the  stratig- 
Iphy  of  the  embayment  area  in  western  Kentucky  and  Tennessee  and  in  correlating  the 
Irmations  found  there  with  those  recently  mapped  in  Mississippi.  The  most  important 
loducts  of  the  area  are  the  extensive  deposits  of  clays.  The  quality  of  some  of  these 
ays  ranks  in  importance  with  the  ball  clays  of  Maryland,  New  York,  and  Ohio. 
I  Common  brick  and  stoneware  have  long  been  made  in  various  parts  of  the  district,  but 
ptil  recently  little  attention  has  been  paid  to  the  rich  deposits  of  fire  brick  and  ball  clays. 
It  fact  there  are  now  but  two  fire-brick  plants  in  the  entire  district,  and  all  the  ball  clays 
bw  being  mined  are  shipped  to  potteries  in  Ohio,  New  York,  and  other  States  to  be  con- 
grted  into  the  finished  product. 
LOCATION. 
The  area  discussed  embraces  all  that  part  of  Kentucky  and  Tennessee  lying  west  of 
ennessee  River  and  includes  about  13,237  square  miles  (see  map,  PI.  XIII).  It  is  a  part 
P  the  Gulf  embayment  and  is  separated  from  the  older  and  harder  rock  district  on  the  east 
v  Tennessee  River.  Ohio  River  forms  the  northern  boundary  from  Paducah,  Ky.,  to 
airo,  111;  Mississippi  River  forms  the  western  boundary  from  Cairo  to  Memphis,  Tenn., 
nd  the  Tennessee-Mississippi  line  forms  the  southern  boundary. 
TOPOGRAPHY. 
The  region  is  a  dissected  plain  with  a  maximum  elevation  along  the  southern  border  of 
bout  600  feet  above  sea  level.  There  is  a  low  swell  extending  from  north  to  south,  parallel 
3  and  about  15  to  25  miles  west  of  Tennessee  River.  The  streams  west  of  this  divide  flow 
rest  and  empty  into  Mississippi  River;  those  on  the  east  side  flow  eastward  and  northward 
lto  Tennessee  River.  Throughout  a  large  portion  of  the  distance  the  divide  is  along  the 
ontact  between  the  Cretaceous  and  the  Tertiary,  and  it  will  be  of  interest  to  note  that  the 
reat  number  of  valuable  clay  deposits  occur  along  the  western  slope  of  the  divide  near  the 
rest. 
GEOLOGY. 
The  oldest  formations  of  this  area  belong  to  the  Paleozoic  rocks,  which  outcrop  in  all  the 
treams  east  of  Tennessee  River  and  in  a  few  places  west  of  it.  They  become  more  deeply 
uried  to  the  west  beneath  the  Cretaceous  and  later  deposits,  and  at  the  western  edge  of 
be  area  wells  bored  1,200  feet  deep  fail  to  strike  the  Paleozoic  rocks. 
The  deposition  of  the  Cretaceous  in  this  region  therefore  followed  a  period  of  deep  erosion 
l  which  a  great  trough  was  scoured  out  at  least  1,200  feet  deeper  than  the  basin  now 
ccupied  by  Mississippi  River.  This  pre-Cretaceous  trough  extended  in  width  from  the 
'aleozoic  hills  in  eastern  Arkansas  and  Missouri  to  the  present  location  of  Tennessee  River 
l  Tennessee  and  Kentucky. 
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