107


again.  The  trap  can  be  traced  along  the  strike  for  some  two  or
three  hundred  yards,  but  no  trace  of  it  appears  on  the  side  of
Swinside,  a  little  to  the  west  of  Bosetrees.  These  phenomena  are
caused  by  the  existence  of  an  enormous  KN.K,  and  W.S.W.  fault,
whereby  almost  the  whole — if  not  the  whole — of  the  Skiddaw  Slates
are  repeated  to  the  south  of  this  point.  The  existence  of  this  fault  was
determined  by  me  in  November,  1868,  and  I  made  out  at  that  time
that  the  upper  boundary  of  the  Skiddaw  Slates,  instead  of  running,
aa  formerly  supposed,  up  the  vale  of  Newlands  to  the  foot  of
Buttermere,  was  really  to  be  found  some  three  miles  to  the  south  of
this  line,  passing  by  Lowdore,  High  Lowdore,  Grange,  and  the
Hollows,  in  a  south-west  direction  towards  the  head  of  Buttermere.
These  facta  will  be  rendered  easily  intelligible  by  the  accompanying
section*'


Faolt.
Fig.  1.  Section  from  Portingacale,  along  the  west  side  of  Derwentwster,  to  Castle  Crag  in
Borrowdale.    Length  of  section  fiTe  miles.
a.  Skiddaw  Slates.
b.  Felspathic  trap,  forming  the  base  of  the  Green  Slate  Series.
c.  CleaTed  Breccias  and  felspathic  ashes  (Green  Slates).
Proceeding  now  to  the  east  side  of  Derwentwater,  the  Skiddaw
Slates  are  seen  at  various  points  between  Lowdore  and  Grange.
