92 
PROF.  T.  G.  BONNET  ON  THE 
[Feb.  1893, 
thicknesses  of  the  rock-masses  or  assert  that  nothing  has  been  over¬ 
looked.  To  make  an  accurate  map  or  a  measured  section  would  take 
several  days’  hard  work  with  the  large-scale  topographical  map  and 
could  only  be  done  by  camping  out  at  the  head  of  the  Eginenthal.1 
The  disturbances  just  in  this  part  of  the  Alps  have  been  very 
great.  Where  indications  of  bedding  can  be  obtained  the  rocks  are 
often  seen  to  dip  at  very  high  angles.2  I  think  the  most  probable 
interpretation  of  the  section  to  be  that  the  dark  schists,  constituting 
the  crest  and  southern  flank  of  the  Yufenenstock,  form  a  sharp 
anticlinal  fold,  being  doubled  back  to  back.  The  Val  Corno,  and 
the  plateau  or  shallow  trough,  occupied  by  the  long  neve  of  the  Gries 
Glacier,  run  along  a  synclinal,  indicated  by  the  rauchwacke  and  by 
some  4  spotted’  Jurassic  rock,  which,  according  to  my  notes  of  1883, 
occurs  on  the  northern  ascent  to  the  Gries  Pass.  At  and  near  the 
top  of  this,  as  shown  by  my  specimens,  black-garnet  schist  occurs, 
and  rocks  belonging  to  the  same  group  continue  for  some  distance 
down  the  southern  side.  On  the  northern  side  of  the  Nufenenstock 
is  another  infold  of  Jurassic  rock,  forming  probably  a  syncline, 
which  is  broken  by  upthrust  faults,  and  so  4  wedges  in  ’  small  strips 
of  rauchwacke,  etc.  The  dotted  lines  on  the  sections  are  intended  to 
give  a  hypothetical  interpretation  of  our  observations.3 
The  Nufenenstock  district  is  interesting  as  exhibiting  the  4  spotted  ’ 
Jurassic  rocks  closer  to  the  black-garnet  schists  than  was  shown  by 
any  sections  noticed  in  my  former  paper,  and  so  facilitating  com¬ 
parison  and  contrast.  The  comparative  abundance  of  the  disthene- 
schist  in  the  rauchwacke  and  the  absence  of  the  black-garnet  schist 
from  it  (for  I  have  not  yet  detected  any  fragments  of  this  rock 
therein)  are  curious.  The  explanation  may  be  found  either  in  some 
peculiarity  in  the  relation  of  the  two  rocks  to  the  old  land-surface, 
or,  more  probably,  in  the  fact  that  the  black-garnet  schist  is  a 
solid  and  durable  rock,  the  disthene-schist  the  reverse. 
I  venture  to  differ  from  Dr.  von  Fritsch’s  map  (which  is  on  a 
larger  scale  and  in  more  detail  than  that  of  the  Swiss  Survey)  on  the 
following  points : — (1)  As  said  in  my  former  paper,  I  consider  the 
strip  traversed  by  the  path  from  All’  Acqua  to  the  Nufenen  Pass, 
which  he  colours  4  black-garnet  schist,’  to  be  Jurassic,  but  I  substitute 
the  former  rock  for  some  of  his  4  Lias.’  (2)  I  should  prefer  to 
colour  the  southern  side  of  the  Nufenenstock  as  4  black-garnet  schist’ 
rather  than  4  calc-mica  schist’ ;  this,  however,  is  a  small  difference. 
(3)  We  did  not  And,  north  of  the  pass  leading  to  the  Yal  Corno,  the 
bread  strip  of  4  marble  ’  Avhich  he  depicts  parallel  to  the  rauchwacke; 
possibly,  however,  only  a  variety  of  the  latter  rock,  and  not  an 
associate  of  the  crystalline  schists,  is  intended.  (4)  Although  this 
1  From  Ulrichen  it  is  about  three  hours’  good  walking  to  the  top  of  the  Gries 
Pass,  and  I  think  the  summit  of  the  Nufenen  stock  coifld  hardly  be  reached, 
even  by  the  easier  climb  from  this  route,  in  less  than  four. 
2  The  actual  peak  of  the  Nufenenstock  seems  to  show  a  kind  of  fan-structure. 
3  The  evidence  is  slight,  but  the  suggestions  may  be  useful  as  a  basis  for  the 
work  of  others.  It  should  be  said  that  the  absence  of  the  rauchwacke  is  not 
important.  This  rock  varies  much  in  thickness  and  often  is  missing. 
