As  a  whole,  the  Liassic  and  Oolitic  series  of  Brora
dip  east  and  north-east  along  the  shore  between  Dun-
robin  and  Helmsdale,  the  older  parts  of  the  series  being


Lias  and  Oolites  of  Scotland.          199

afc  Dunrobin,  and  the  younger  at  and  near  Helmsdale
A  great  fault,  nearly  20  miles  in  length,  runs  along  the
shore,  and  throws  the  secondary  strata  down  against  the
older  Palaeozoic  rocks  on  the  north-west.  Interstrati-
fied  with  the  black  shales  near  Helmsdale,  there  are
occasional  beds  of  brecciated  conglomerate.  The  shales
contain  thin  layers  of  plants  and  many  broken  shells,
and  the  breccias  contain  angular  and  subangular
blocks,  chiefly  of  Old  Red  Sandstone,  with  a  mixture  of
the  older  rocks  of  the  Highlands,  sometimes  6  or  8  feet
in  diameter,  in  fact,  boulder  beds,  which  long  ago
suggested  to  me  the  action  of  floating  ice.  Mr.  Judd
suggests  that  they  may  be  due  to  river  ice,  floated  on
streams  flowing  from  the  west,  at  a  time  when  the  larger
part  of  the  gneiss  of  the  Highlands  was  covered  by  Old
Red  Sandstone,  since  denuded.
In  the  Inner  Hebrides,  the  Lias,  Inferior  Oolite,
Middle  Oolite  and  Oxford  Clay  occur  in  the  Island  of
Skye.  The  Lias,  as  described  by  Geikie,  consists  of  beds
of  limestone,  sandstone,  conglomerate,  and  shale.  It
contains  the  usual  fossils.  The  rocks  are  much  dis-
turbed, and  the  limestones  have  been  metamorphosed
into  crystalline  marble  accompanied  by  the  intrusion  of
syenite.  The  section  at  Loch  Staffin,  given  by  Edward
Forbes,  is  as  follows: —

Oxford  Clay.  Inferior  Oolite.
Estuary  Shales.  Lias.
Middle  Oolite.
