318         CONTRIBUTIONS   TO   ECONOMIC   GEOLOGY,   1907,    PART   II. 
SURFACE  FEATURES. 
The  Grand  Mesa  coal  field  is  characterized  by  a  very  uneven  sur- 
face. In  the  western  and  southern  parts  a  broad  belt  of  compara- 
tively low  relief  borders  a  flat-topped  table-land  that  rises  to  an 
altitude  of  more  than  10,000  feet  above  the  sea,  or  a  mile  vertically 
above  the  lowlands.  In  the  middle-ground,  where  the  coal  crops 
out  there  is  a  belt  of  rugged  country  that  differs  in  character  from 
place  to  place  according  to  the  underlying  rocks.  Below  the  coal 
the  rock  consists  of  soft  shale  which  is  covered  in  many  places  with 
fragments  of  basalt  derived  from  the  sheet  that  caps  the  mesa.  The 
shale  is  carved  by  erosion  into  broad,  tongue-shaped  mesas  and  bad- 
lands consisting  of  sharp  irregular  ridges  and  V-shaped  ravines. 
Above  the  coal  there  are  hard  sandstones  that  form  precipitous 
cliffs  in  some  places  and  steep  wooded  or  debris-covered  slopes  in 
others. 
Near  the  east  end  of  the  field  the  surface  configuration  differs 
from  that  to  the  west  in  the  absence  of  lowlands  and  the  presence  of 
high  mountains  that  rise  above  the  surface  of  the  mesa.  Narrow 
canyons  have  been  cut  by  the  streams  to  depths  of  2,000  feet  or  more 
in  the  hard  sandstone  that  overlies  the  coal.  The  highlands  are 
covered  more  or  less  completely  with  timber,  consisting  principally 
of  cedar  in  the  western  part  of  the  field,  and  spruce,  pine,  and  other 
.forest  trees  farther  east.  In  many  places  the  cedars  form  dense 
thickets  and  the  trees  grow  to  considerable  size,  but  few  of  the 
trunks  are  sound  and  they  do  not  make  good  mine  props.  However, 
the  pine  and  spruce  trees  that  grow  in  considerable  abundance  in  the 
canyons  and  on  the  mountain  sides  in  the  eastern  part  of  the  field 
are  suitable  for  mining  purposes. 
The  highlands  have  further  potential  importance  in  connection 
with  the  coal,  inasmuch  as  they  furnish  the  only  supply  of  water 
available  in  many  places.  Near  Palisades  and  Somerset  the  rivers 
furnish  all  water  necessary  for  domestic  purposes  and  for  such  coal 
washeries  as  may  be  needed,  but  in  the  greater  part  of  the  field  the 
coal  is  far  above  the  river  level  and  the  only  available  water  is  that 
supplied  by  numerous  small  streams  from  Grand  Mesa.  These 
highland  waters  are  of  good  quality  and  with  proper  manipulation 
they  can  be  delivered  in  any  part  of  the  field  in  quantities  sufficient 
for  mining  purposes.  The  waters  that  issue  from  the  shale  below 
the  coal  or  that  flow  over  it  are  highly  charged  with  salts  that  render 
them  unfit  for  domestic  use. 
The  means  of  approach  to  the  coal  are  shown  on  the  accompany- 
ing map  (PI.  XXI)  and  require  little  comment.  The  main  line  of 
the  Denver  and  Rio  Grande  Railroad  crosses  the  coal  outcrop  at  the 
northern  border  of  the  field  and  a  branch  of  this  road  runs  to  the 
