300 
CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1904.         [bull.  260. 
uplands,  and  to  the  higher  parts  of  the  slopes,  where  it  has  probably 
been  washed  down  from  the  deposits  in  place  above,  but  in  the  south- 
western third  of  the  coal-bearing  area  the  distribution  of  the  un- 
consolidated rocks  is  more  general.  The  thickness  of  this  material 
varies  from  a  few  feet  along  the  northeastern  limit  to  probably  more 
than  100  feet  along  the  southwestern  margin  of  the  field. 
The  Carboniferous  or  coal-bearing  rocks  are  shales  and  sandstones 
of  Pottsville  age,  and  are  in  general  the  equivalents  of  the  rocks  of 
the  New  River  and  Kanawha  coal  fields  of  West  Virginia  and  of  the 
anthracite  coal  field  of  Pennsylvania. 
Below  is  a  general  section  of  these  rocks  compiled  from  measure- 
ments made  at  different  points. 
The  section  extends  down  to  the  top  of  the  thick  quartzitic  sand- 
stone, forming  by  its  nearly  vertical  outcrop  the  prominent  ridge  of 
Rock  Mountain,  and  the  total  thickness  of  the  included  rocks  is  about 
8,000  feet. 
Generalized  section  of  Carboniferous  rocks  of  Warrior  field. 
Character  of  rocks. 
Thickness. 
Aver- 
age. 
Mini- 
mum. 
Maxi- 
mum. 
Shale 
Sandstone  ... 
Shale,  with  sandstone  below  locally 
Brookwood  coal 
Sandstone 
Milldale  coal 
Sandstone 
Johnson  or  Carter  coal 
Sandstone 
Shale  and  sandstone 
Gwin  coal 
Shale 
Sandstone . 
Thompson  Mill  coal. 
Shale 
Cobb  npper  coal 
Shale  and  sandstone 
Cobb  lower  coal 
Sandstone 
Shale 
Pratt  coal 
Feet. 
50 
30 
100 
5 
35 
40 
21 
25 
160 
21 
15 
70 
II 
145 
n 
20 
H 
40 
220 
3± 
Feet. 
Feet. 
30 
40 
1 
21 
1 
21 
1 
4 
5 
25 
20 
120 
1 
n 
70 
220 
1 
n 
1 
o 
20 
60 
160 
280 
1* 
5 
