292  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   1906,  PART    I. 
with  Turkey  Creek,  though  it  probably  varies  much  in  thickness  and 
quality  in  this  area. 
This  deposit  of  clay  accumulated  during  the  time  that  the  creek 
waters  were  more  or  loss  ponded  from  some  cause,  for  the  clay  is 
evidently  composed  of  fine  material  that  was  washed  down  from  the 
surrounding  hills  and  slowly  settled  in  still  water.  The  cause  of  the 
ponding  may  have  heen  a  stratum  of  sandstone  which  crosses  Turkey 
Creek  near  the  bridge  south  of  Morris  and  which  retarded  the  down- 
cutting  of  the  creek  bed  and  acted  as  a  dam  to  the  water  above. 
The  only underclay utilized  in  the  Birmingham  quadrangle  is  that 
under  the  Black  Creek  coal  seam  at  Coaldale  and  vicinity.  It  is  a 
gray  plastic  clay  and  makes  a  hull'  brick.  It  has  been  mined  near 
the  Southern  Clay  Company's  brick  works  at  Coaldale  and  at  the 
Butterfly  mine,  aboul  1  mile  east  of  Coaldale.  At  both  points  it  is 
I  feet  thick,  [ts  further  extension  is  unknown  to  the  writer,  hut 
there  is  evidently  a  considerable  body  of  good  clay  in  this  locality. 
From  both  the  places  just  mentioned  the  clay  has  heen  shipped  to 
Birmingham  and  Bessemer  for  lire  brick  and  terra  cotta.  It  is  now 
being  mined  at  the  Butterfly  mine  by  the  Sibley-Menge  Press  Brick 
Company  foi'  use  in  its  new  works  1  mile  north  of  Coaldale.  It  is 
used  for  dry-press  face  brick  of  hull"  color,  is  mixed  with  shale  for 
gray  brick,  and.  with  the  addition  of  manganese,  is  used  for  speckled 
brick. 
A  bed  of  clay  4  to  6  feet  thick  underlies  the  Nickel  Plate  or  Ameri- 
can coal  -cam  at  Baileys  Quarters,  northeasl  of  Brookside,  where  it 
is  exposed  in  a  cut  of  the  North  Alabama  Railroad.  The  same  clay 
also  shows  in  a  cut  of  this  railroad  at  ('lift  station.  Here  there  are 
three  beds,  two  of  which  are  each  2  feet  thick  and  one  IS  inches 
thick.  A  bed  of  clay  :\  to  I  feet  thick  occurs  at  the  same  horizon  at 
Short  Creek,  and  clay  of  greater  or  less  thickness  has  heen  noted 
under  the  same  coal  at  other  points  in  the  region.  It  has  not  heen 
utilized  and  nothing  is  known  of  its  qualities. 
A  bed  of  very  white,  -oft .  plastic  clay.  2\  feet  thick,  underlies  the 
Pratt  seam  at  the  Thompson  mine,  northwest  of  Sayreton,  hut  gen- 
erally the  coal  seams  of  this  region  appear  to  he  without  underclays 
of  economic  importance. 
SHALE. 
The  Alabama  coal  measures,  reaching,  in  the  deepest  part  of  the 
Cahaba  trough,  nearly  7,000  feet  in  thickness,  are  made  up  of  alter- 
nating shale  and  sandstone,  the  shale  forming  about  two-thirds  of 
the  whole.  Most  of  the  shale  is  probably  suitable  for  brick  making. 
Shale  from  three  different  horizons  in  the  Warrior  basin  and  from 
one  horizon  in  the  Cahaba  trough  is  now  being  utilized  for-  brick. 
A  project  is  afoot  to  use  a  lower  Carboniferous  shale  for  the  same 
purpose  also. 
