330         CONTRIBUTIONS   TO   ECONOMIC   GEOLOGY,   1907,   PART   II. 
the  other  districts.  The  average  thickness  of  workable  coal  is  prob- 
ably not  less  than  65  feet.  The  productive  beds  occur  at  various 
horizons  throughout  the  Bowie  shale,  and  range  in  thickness  from  4 
to  25  feet.  The  lowest  coal  is  worked  at  the  Conine  mine  (No.  35), 
where  the  bed,  15  feet  8  inches  thick,  consists  of  two  benches  sepa- 
rated by  1  foot  G  inches  of  shale.  The  coal  of  the  middle  and  upper 
parts  of  the  Bowie  shale  is  worked  at  the  Cooperative  mine  (No. 
36),  where  the  bed  is  10  feet  8  inches  thick;  at  the  new  King  mine 
(No.  38),  where  it  is  12  feet  8  inches  thick;  and  at  the  Somerset 
mine,  where  it  is  said  to  be  still  thicker  on  account  of  the  coalescence 
of  several  beds. 
The  coal  is  better  in  many  ways  than  the  fresh-water  coal  of  the 
Rollins  district.  It  is  harder,  less  liable  to  slack  on  exposure  to  the 
weather,  stands  shipment  well,  and  some  of  it  is  coking  coal.  It 
is  black,  bituminous,  fine  grained,  with  bright  vitreous  luster  and 
texture  ranging  from  even  to  seamy,  and  some  of  it  is  conspicu- 
ously banded  by  alternating  layers  of  coal  that  differ  in  luster.  The 
coal  throughout  the  district  is  free  from  bone  or  other  foreign  mat- 
ter that  seriously  interferes  with  mining  or  marketing. 
Sections  of  coal  beds  in  the  Somerset  district,  Grand  Mesa  coalfield,  Colorado. 
£5 
Name  and 
location  of 
mine. 
Section. 
Name  and 
location  of 
mine. 
Section. 
35 
Conine;  NW.J 
SE.  \  sec.  24, 
T.  13  S.,  R. 
92  W. 
Shale. 
Coal 
Shale 
Coal 
Shale 
Ft.i 
7 
1 
6 
2 
n. 
8 
6 
6 
8 
39 
40 
Pro  spect  on 
Hubbard 
Creek;     sec. 
12,  T.  13  S., 
R.  91  W. 
Shale. 
Coal 
Sandstone. 
Ft.  in. 
..     12 
17 
Mallott;     sec. 
24,  T.  13  S., 
R.  91  W. 
Shale,  sandy. 
Coal 
Shale 
Coal 
Shale,  sandy. 
..4    2 
2 
..     12 
36 
Cooperative; 
SW.  \  SW.  J 
sec.  17,  T.  13 
S.  R.  91  W. 
Sandstone. 
Coal,  bony 
Coal 
Shale,  carbonaceous . 
2 
8 
8 
6 
16    4 
11 
2 
41 
Whitlaw;  sec. 
23,  T.  13  S., 
R.  91  W. 
Shale. 
Coal 
37 
King    (old); 
NE.JNW.1 
sec.  15, T.  13 
S.,R.91W. 
Shale. 
Coal 
Coal,  bony 
Sandstone. 
4 
4 
..     21 
43 
Sylvester;  sec. 
10,  T.  13  S., 
R.  90  W. 
Shale. 
Coal 
Shale. 
..       5  10 
4 
4 
38 
King  (new); 
NE.JNE.i 
sec. 15, T.  13 
S.,  R.  91  W. 
Shale,  carbonaceous. 
Coal 
Shale 
Coal 
Coal   ("sulphur 
streak") 
Coal 
Shale,  carbonaceous . 
1 
3 
6 
2 
3 
7 
4 
8 
8 
45 
Hawks  Nest; 
sec.  11, T.  13 
S.,  R.  90  W. 
Shale. 
Coal 
Base  not  exposed. 
.      7 
46 
Shoecroft 
(Porter 
claims) ;  sec. 
32,  T.  13  S., 
R.90W. 
Shale. 
Coal 
Shale. 
..      7 
12 
8 
