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MISS  OGILVIE  OH  THE  WENGEX  AND 
[Feb.  1893, 
Ever  since  its  first  publication  the  coral-reef  theory  has  had  its 
opponents.  In  the  year  1872  Giimbel1  published  a  paper  on 
the  Mendola  and  Schlern  mountains,  in  which  he  gave  several 
sections,  and  made  a  comparison  between  the  succession  of  Triassic 
strata  in  Northern  and  Southern  Tyrol.  He  proved  that  the  Men¬ 
dola  and  Schlern  Dolomites  could  be  distinguished  as  palaeontological 
horizons.  In  the  Mendola  Dolomite  the  fossil  of  most  frequent 
occurrence  is  Gyroporella  pciuciforata,  Giimbel,  characteristic  of  the 
Muschelkalk  in  the  Northern  Alps,  whereas  in  the  Schlern  Dolomite 
other  species  of  GyroporeJla  occur,  especially  G.  annulatci ,  Schafh., 
common  in  the  Wetterstein  Kalk  in  Northern  Tyrol.  Giimbel 
defined  the  Schlern  Dolomite  in  a  twofold  sense : 
1.  As  the  doiomite-rock  equivalent  in  age  to  the  whole  series  of 
sedimentary  strata,  from  the  lowest  St.  Cassian  Beds  exposed  on  the 
Seisser  Alpe  (Bichthofen’s  ‘Sedimentary  Tuffs  ’  included  here)  to 
the  ‘  Bed  Baibl  Beds  ’  of  the  Schlern  plateau. 
2.  As  the  dolomite-rock  denoting  a  distinct  palaeontological 
horizon  lying  above  the  St.  Cassian  strata  and  below  the  Baibl  strata. 
Giimbel  opposed  Bichthofen  s  coral-reef  theory,  chiefly  on  the 
ground  that  there  was  little  proof  of  coral  agency,  corals  being 
seldom  found  in  the  Schlern  Dolomite,  whereas  algae  such  as 
Gyroporellce  are  often  obtained  and  with  their  fine  structure  well- 
preserved.  He  also  showed  that  the  variation  in  thickness  of  the 
Schlern  Dolomite  was  analogous  to  the  variation  in  other  rocks,  such 
as  the  Wetterstein  Ivalk  in  the  Bavarian  Tyrol.  These  objections 
of  Giimbel  were  replied  to  by  Bichthofen  in  a  paper  ‘  ITeber  Mendola- 
Dolomit  u.  Schlern-Dolomit.’2 
Loretz,3  who  published  the  first  detailed  study  of  the  Ampezzo 
district  in  two  papers  (1874-75),  did  not  accept  the  reef-theory. 
At  the  same  time  he  recognized  two  equivalent  facies  of  strata,  a 
dolomitic  and  a  non-dolomitic,  representing  the  period  between  the 
Muschelkalk  and  the  Baibl  strata.  In  this  he  anticipated  the  view  of 
the  complete  ‘  heteropic  ’  development  of  the  Buchenstein,  M  engen, 
and  St.  Cassian  zones  held  by  Mojsisovics. 
Lepsius,4  in  his  work  on  the  Nonsberg  massif \  south-west  of  the 
Schlern  mountains,  concluded  that  the  Schlern  Dolomite  in  that 
district  was  a  stratified  marine  deposit,  covering  an  immense  area, 
and  that  the  same  deposit  varied  in  thickness  in  the  Schlern  and 
Fassa  districts,  mainly  owing  to  the  outpouring,  during  its  period 
of  deposition,  of  masses  of  volcanic  matter. 
1  £  Das  Mendel-  u.  Scblern-Gebirge,’  Sitzungsb.  d.  math.-phys.  Classe  cl.  k. 
bayerisch.  Akad.  d.  Wissensch.  vol.  iii.  (1873)  p.  14. 
2  Zeitscbr.  d.  Deutscb.  geol.  Gesellsch.  vol.  xxvi.  (1874)  p.  22o.  ^ 
3  ‘  Das  Tirol-Venetianische  Gfrenzgebiet  der  Gegend  von  Ampezzo.  ibid. 
p.  377 ;  ‘  Einige  Petrelacten  der  alpinen  Trias  aus  den  Sudalpen,’  ibid.  vol. : 
(1875)  p.  784. 
4  ‘Das  Westlicbe  Siid-Tirol,’  Berlin,  1878;  see  particularly  pp.  77-83. 
.  xxv  11. 
