butts.]  WARKIOR   COAL   BASIN,   ALABAMA.  859 
PHYSICAL   FEATURES. 
The  surface  of  the  Warrior  basin  is  in  large  part  characterized  by 
long,  narrow  ridges  and  spurs  separated  by  narrow  valleys  and 
ravines.  The  tops  of  these  ridges  have  a  general  altitude  of  from 
500  to  600  feet  above  sea  level.  In  the  northeastern  corner  of  the 
quadrangle  are  large  level  tracts,  which  have  an  elevation  of  approxi- 
mately 500  feet.  These  features  indicate  that  the  region  formerly 
had  a  nearly  level  surface,  the  remnants  of  which  are  the  areas  above 
500  feet.  This  old  surface  has  been  minutely  dissected  by  the 
streams  of  the  region  and  the  present  irregular  topography  produced. 
Black  Warrior  River  crosses  the  northwestern  part  of  the  quad- 
rangle and  drains  the  entire  area  under  consideration.  Its  principal 
tributary  is  Valley  Creek,  a  stream  of  considerable  size,  which  has 
its  source  in  the  limestone  valley  region  to  the  southeast,  and,  after 
crossing  the  northeastern  part  of  the  quadrangle,  reaches  Black 
Warrior  River  a  short  distance  north  of  its  northern  boundary. 
Davis  Creek,  crossing  the  central  part  of  the  field,  and  Hurricane 
Creek,  in  the  southern  part,  are  important  streams.  Yellow  Creek 
and  Blue  Creek  are  the  principal  streams  west  of  the  river. 
These  streams  are  of  considerable  importance  on  account  of  the 
quantity  of  water  needed  by  coal  washeries.  Should  need  be  in  the 
future,  Valley  Creek,  Hurricane  Creek,  and  Yellow  Creek  will  prob- 
ably furnish  abundance  for  that  purpose.  They  were  flowing  a 
good  volume  well  up  toward  their  heads  in  the  fall  of  1903,  even 
though  the  rainfall  of  the  preceding  season  or  two  had  been  much 
lighter  than  ordinary.  Davis  Creek,  from  which  water  is  drawn 
for  use  in  the  washer  at  the  Central  mine,  failed  in  the  protracted 
drought  of  last  season. 
Although  the  region  in  general  is  rather  rugged,  the  valleys  with 
their  tributaries  make  most  parts  of  the  Warrior  basin  in  the  quad- 
rangle accessible  to  railroads  without  presenting  any  great  engi- 
neering difficulties.  This  makes  possible  the  cheap  transportation 
of  the  coal. 
STRATIGRAPHY. 
The  Warrior  coal  basin  is  the  southwestern  end  of  the  Appalachian 
coal  field  of  the  eastern  United  States.  Its  rocks  are  a  thin  sur- 
ficial  deposit  of  unconsolidated  sands,  clays,  and  gravels  of  Tertiary 
and  Cretaceous  age,  and  a  great  thickness  of  Carboniferous  rocks. 
In  the  Brookwood  quadrangle  the  northeastern  limit  of  the  uncon- 
solidated deposits  is  roughly  a  line  extending  from  the  northwest- 
ern corner  of  the  quadrangle  to  beyond  Milldale,  though  gravel 
occurs  on  some  of  the  higher  hills  to  the  northeast.  Generally  the 
unconsolidated  material  is  confined  to  the  hilltops,  ridges,  and  level 
