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CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,    1905. 
GEOLOGY. 
STRATH  iKAIMIY. 
The  coal-bearing  rocks  are  of  Pottsville  age,  like  those  of  the  New  River  and  Kanawha 
coal  fields  of  West  Virginia  and  the  lower  rocks  of  the  anthracite  fields  of  Pennsylvania. 
They  arc  sandstone  and  shale,  with  occasional  thin  limestones.  The  sandstone  horizons 
are  persistent,  and  some  particular  l>eds  can  be  traced  over  large  areas.  The  coal  seams 
are  generally  closely  associated  with  sandstone.  The  total  thickness  of  rocks  from  the 
highest  \>v(\s  in  the  center  of  the  syncline  to  the  bottom  of  the  Black  Creek  coal  seam,  as 
compiled  from  measurements  in  different  parts  of  the  basin,  is  1,216  feet.  Below  is  a 
generalized  section: 
Generalized  section  of  coal-bearing  rocks  above  tin  floor  of  the  Black  ("red-  cool. 
Horizon  oi  Gwin  coal. 
Shale 
Sandstone 
Shale 
Coal    Cobb) 
Shale 
Sandstone 
shale  and  sandstone 
Coal  (Pratt) 
Sandstone 
Coal  I  Nickel   Plate) 
Sandstone 
Shale 
Coal  (Curry) 
Shale  and  sandstone 
Coal  (Gillespie) 
Shale  and  sandstone 
Coal    Newcastle) 
Shale 
Coal  i  Mary  1 
Shale  or  sandstone   
Coal  (Blue  Creek) 
Shale,  sandstone,  or  conglomerate 
Coal  (.(agger) 
Shale 
Sandstone  and  conglomerate 
Coal  f  Ream  i 
Sandstone 
Shale 
Coal  i  hick  Creek) 
Shale  and  sandstone 
Coal  (Jefferson  i 
Shale  and  sandstone 
Coal  (Black  Creek) 
Shale  and  sandstone. 
Thickness.     Depth, 
Feet. 
10 
30 
LOO 
2 
5 
40 
260 
3.  5 
35 
2.5 
20 
40 
1 
30 
.5 
313.5 
2 
28 
6 
60 
2 
50 
3 
10 
25 
1 
40 
40 
1 
40 
2.5 
30 
2.5 
Feet. 
10 
40 
140 
142 
147 
,87 
447 
450. 5 
485. 5 
488 
508 
548 
549 
579 
579.  5 
893 
895 
923 
929 
991 
1.041 
1,044 
1,054 
1,079 
1,080 
1,120 
1,160 
1,161 
1,181 
1,183.5 
1.213.5 
1,216 
En  this  section  the  details  of  thickness  and  character  of  the  rocks  are  only  an  approximate 
average,  but  the  intervals  between  the  principal  coal  beds  are  fairly  correct.  The  distance 
between  the  Cobb  and  Pratt  coal  beds  was  determined  west  of  Wylam  and  Ensley,  where 
the  elevation  of  the  Cobb  coal  was  determined  from  its  outcrop,  and  the  elevation  of  the 
