Tol.  49.]  ST.  CASSIAS  STEATA  IX  SOT7THEEX  TYEOL.  63 
the  lower  part  of  the  Freiner  Bach,  along  with  a  great  many  blocks 
of  Buchenstein  limestone ;  bnt  the  strata  are  largely  hidden  by  all 
kinds  of  debris.  They  strike  in  an  east-and-west  direction  across 
the  valley  at  St.  Cassian.  Immediately  north  of  St.  Cassian  is  a 
thick  mass  of  augit e-porphyry,  and  above  it  follow  the  Wengen 
shales  containing  Hdlobia  Lommeli.  The  higher  Wengen  horizons 
and  the  St.  Cassian  strata  form  the  Bn  and  Peravnda  slopes  on 
the  north.  At  St.  Cassian,  therefore,  a  small  outcrop  of  augite- 
porphyry  and  iTaZoMa-shales  is  cut  off  on  all  sides,  except  Langs- 
da-fiir,  against  younger  strata,  the  outcrop  being  essentially  a 
continuation  of  the  Langs-da-fiir  anticline,  only  slightly  disjointed. 
To  return  now  to  the  central  Prelongei  succession,  we  may  con¬ 
sider  it  as  a  shallow  synclinal  exposure  of  Wengen  and  St.  Cassian 
strata.  Southward  (Selvaza  or  Buchenstein  Alpe)  the  series  of 
beds  dip  at  a  small  angle,  15°  to  20°  north,  whereas  on  Stuores 
Wiese,  wherever  a  sure  reading  of  the  beds  in  their  true 
position  is  obtainable,  they  are  found  to  dip  at  a  still  smaller  angle 
(5°  to  10°)  south.  The  most  fossiliferous  St.  Cassian  horizons  are 
found  on  the  ridge  of  Prelongei,  and,  as  I  have  already  said, 
are  repeated  in  Buones  lEuren  (see  fig.  1,  p.  17).  For,  towards 
Corvara,  the  strata  on  Prelongei  are  twice  let  down  by  small  step- 
faults.  A  large  district  in  the  north-west,  known  as  ‘  Siadu,’  is  also 
faulted  down  from  the  Prelongei  succession,  so  that  the  St.  Cassian 
strata,  which  are  in  position  between  Sorega  and  the  Piecol  Bach, 
have  a  quite  different  strike-system  from  the  strata  between 
the  latter  stream  and  the  Stuores  Bach.  Xumerous  blocks  and  an 
unusual  thickness  of  dolomitic  debris  cover  the  St.  Cassian  Beds  of 
Siadu,  and  indicate  the  presence  at  a  former  period  of  a  continuous 
bank  of  Schlern  Dolomite  in  that  locality. 
The  palaeontological  difficulties  introduced  by  the  landslips  on  the 
Stuores  Wiesen  have  already  been  touched  upon  (p.  18).  The  con¬ 
stant  sliding  down  of  younger  strata  upon  older  strata,  and  of  a  whole 
piece  of  meadow  into  a  secondary  and  quite  irrelevant  position,  may 
be  observed  at  every  part  of  the  northern  slopes  of  Prelongei. 
The  soft  marls,  shales,  and  ashy  Wengen  Beds  become  saturated 
with  water,  and  give  way  under  the  St.  Cassian  marls,  with  their 
numerous  interstratified  beds  of  hard  Cipit  Limestone.  Slips  then 
occur  in  the  St.  Cassian  strata  on  a  more  or  less  grand  scale,  and 
one  finds  remnants  of  thick  St.  Cassian  limestone  at  varying  heights, 
looking  at  first  sight  like  tongues  of  limestone  thinning  out  in  the 
fossiliferous  marls,  and  only  with  difficulty  recognized  as  the  broken 
and  slipped  fragments  of  originally  continuous  beds. 
Aaturally  the  slips  occur  more  readily  on  Prelongei  than  in  cases 
where  Schlern  Dolomite  rock  still  remains  as  a  protection  upon  the 
St.  Cassian  strata.  The  mossy  hollows  and  high  meadows  of  Pre¬ 
longei  form  an  extensive  eroded  surface  exposed  to  the  action  of 
heavy  rains,  melting  snow,  and  swollen  streams,  and  the  down-wash 
of  centuries  is  spread  as  a  loose  soil  upon  the  outcrop  of  older 
beds. 
