van  htsf.]  DISCUSSIONS    OF    PRINCIPLES.  505 
tered  strata,  mostly  shales.  The  lower  consists  of  completely  crystal- 
fine  regularly  bedded  gneisses,  quartz -schists,  quartzites,  chlorite  schists 
and  mica-schists.  The  upper  series,  the  topmost  of  the  Algonkian,  is 
separated  from  the  Archean  by  a  great  unconformity.  The  relations 
of  the  lower  series  of  the  Algonkian  to  the  basal  complex  are  unknown, 
but  it  is  known  to  lie  unconformably  below  the  Cambrian.  Also  the  t  w<  > 
Algonkian  series  are  not  found  in  contact,  but  that  there  are  two  series 
is  indicated  by  the  facts  that  one  of  them  is  conformably  below  the 
Cambrian  while  the  other  is  not,  and  the  first  is  nearly  unaltered  while 
the  second  is  crystalline.  There  is  no  sufficient  information  upon  which 
to  correlate  either  of  the  Algonkian  series  with  the  region  about  lake 
Superior.  The  affinities  of  the  Upper  Algonkian  are  rather  with  prob- 
able Algonkian  series  to  the  west  yet  to  be  considered. 
THE   UINTA  MOUNTAINS. 
An  ancient  clastic  series  in  the  Uinta  mountains  covers  an  area  of 
several  thousand  square  miles.  This  series,  12,500  feet  in  thickness,  is 
one  of  red  quartzites  and  sandstones,  interstratified  with  layers  of  slate 
and  ferruginous  shale.  It  rests  upon  the  upturned,  truncated  edges 
of  a  thoroughly  crystalline  complex  which  is  probably  the  equiva- 
lent of  the  Archean  of  other  regions.  It  is  unconformably  below  the 
Carboniferous.  There  is,  then,  no  definite  evidence  upon  which  this 
series  can  be  referred  to  the  Algonkian.  It,  however,  in  lithological 
character,  absence  of  fossils,  and  position,  is  more  nearly  analogous 
with  the  quartzite  series  of  the  Upper  Huronian  than  any  other  to  the 
east,  but  the  distance  which  separates  it  from  the  Upper  Huronian  is 
so  great  as  to  render  correlation  on  this  ground  very  unsafe.  The  series 
may,  with  more  probability,  be  regarded  as  the  equivalent  of  the  slates 
of  southwestern  Montana  and  the  probable  Upper  Algonkian  of  the 
Wasatch  to  be  considered.  Also  it  is  possible  that  it  may  not  be  Algon- 
kiau  at  all,  but  Cambrian  or  Silurian. 
THE  WASATCH  MOUNTAINS. 
In  the  Wasatch  mountains  the  Algonkian  is  probably  represented 
by  one  series,  and  perhaps  by  two.  The  supposed  Upper  Algonkian  is 
a  series  of  quartzites,  sandstones,  and  micaceous  shales  and  mica-schists 
1 2,000  feet  in  thickness.  It  is  possible  that  below  this  series,  separated 
by  an  unconformity,  is  another  more  ancient  and  crystalline  series  which 
belongs  with  the  Algonkian,  represented  by  the  small  area  of  quartz- 
ites and  quartz -schists  at  the  foot  of  the  Cottonwood  canyons.  The 
Upper  Algonkian  is  separated  by  a  great  unconformity  from  the  Archean. 
Its  relations  to  the  supposed  older  series  of  elastics  in  the  lower  Cotton- 
wood are  not  made  out,  but  it  rests  conformably  under  the  Olenellus 
Cambrian,  and  therefore  if  not  Cambrian  is  uppermost  Algonkian.  This 
series  occupies  the  same  position  as  the  series  of  slates  in  southwestern 
Montana,  and  the  two,  as  has  been  said,  are  perhaps  the  equivalent  of 
the  Uinta  series. 
