vanhisb.]  THE    CORDILLERAS.  313 
quartz-schists,  which  are  iiiterstratified  with  beds  of  conglomerate. 
In  passing  downward  the  mica- schists  become  interlaminated  with 
gneiss,  which  becomes  more  and  more  abundant,  and  upon  Coal  creek 
cutting  the  schists  are  also  pegmatitic  granite  veins.  Nowhere  between 
the  clastic  and  gneissoid  series  was  any  discordance  discovered,  there 
appearing  to  be  between  them  a  gradation,  although  a  somewhat  rapid 
one.  The  clastic  series  at  South  Boulder  creek  is  at  least  1,000  feet 
thick.  The  lower  gneissoid  series  at  times  is  in  part  quite  regularly 
laminated,  at  other  times  becomes  a  heavily  bedded  granite-gneiss,  but 
for  several  miles  toward  the  core  of  the  mountains,  as  far  as  investi- 
gated, does  not  become  structureless  granite. 
On  Coal  creek,  at  one  place  within  the  clastic  series,  is  a  wedge  of 
granite  of  considerable  thickness,  and  this  does  not  grade  into  the 
clastic  rocks  as  does  the  main  granitoid  gneiss  area.  The  relations  of 
the  Trias  both  to  the  granite- gneiss  and  to  the  clastic  series  are  such 
as  to  show  that  it  is  clearly  a  later  forinatiou  separated  from  them  by 
a  very  great  unconformity. 
At  Ralston  creek  the  heavily  bedded  gneisses  were  found  to  vary 
into  hornblende-gneiss  interlaminated  with  granite  veins,  and  these 
into  rather  fine  grained  schistose  rock,  but  there  was  discovered  here  no 
clear  evidence  of  a  clastic  series,  although  the  more  schistose  phases 
immediately  under  the  Trias  may  represent  the  more  altered  clastic 
schists  of  Coal  and  South  Boulder  creeks. 
LITERATURE   OP  THE   WET  AND    SANGRE   DE   CRISTO   MOUNTAINS. 
Schiel,38  in  1885,  describes  the  predominating  rock  of  the  Sangre  de 
Cristo  valley  as  a  feldspathic  granite,  passing  gradually  into  a  gneiss 
on  the  right  bank  of  the  creek,  the  gneiss  supporting  a  hard,  shaly 
sandstone  and  a  bluish  brittle  limestone. 
Endlich,43  in  1874,  describes  the  region  south  of  the  Arkansas  as 
consisting  chiefly  of  granite.  That  forming  the  Sangre  de  Cristo 
mountains  is  of  different  character  and  appearance  from  that  of  the 
Front  range.  The  Wet  mountains  are  regarded  as  eruptive.  Gneiss 
occurs  in  this  range  at  Hunts  peak  and  from  there  6  or  7  miles  to  the 
northwest,  and  is  regarded  as  metamorphic,  although  it  weathers  more 
like  granite  than  a  stratified  rock.  From  the  granite  axis  of  the 
Sangre  de  Cristo  the  sedimentary  rocks  dip  away  both  to  the  east  and 
west.  The  eruptive  granite  of  the  Sangre  de  Cristo  is  the  youngest  of 
the  region.  Although  the  Sangre  de  Cristo  range  is  spoken  of  as  erup- 
tive, this  is  not  considered  to  be  so  in  the  same  sense  that  basalt  is  erup- 
tive, but  to  imply  that  the  granite  by  some  vertically  acting  force  ha% 
been  thrown  upward  and  may  now  be  in  contact  with  strata  which  were 
once  above  it. 
Cope,47  in  1875,  states  that  in  the  Sangrede  Cristo  mountains  is  strati- 
fied granite,  which  is  either  heavily  bedded  feldspathic  porphyry  or 
finely  bedded  hornblende-gneiss. 
