ANNIVERSARY  ADDRESS  OE  THE  PRESIDENT. 
Vol.  49.] 
117 
remarking  that  where  the  Carstone  thins  out  to  nothing  in  the 
north  the  Red  Chalk  becomes  increasingly  conglomeratic  in  cha¬ 
racter.  This  is  certainly  the  case  in  the  outcrops  on  the  western 
escarpment  of  the  Yorkshire  Wolds.  We  have  already  seen  that 
Mr.  Lamplugh  places  the  Carstone  on  the  horizon  of  the  Belemnites 
minimus- marls  of  the  Speeton  section.  If  these  views  are  correct, 
the  Carstone  would  seem  to  belong  almost  as  much  to  the  Upper 
as  to  the  Lower  Cretaceous. 
The  last  paper  which  remains  for  consideration  in  connexion 
with  Lower  Cretaceous  Geology  is  that  by  Mr.  Lamplugh,  already 
quoted,  ‘  On  the  Subdivisions  of  the  Speeton  Clay.’  There  are  so 
many  issues  involved  in  this  paper,  which  almost  opens  up  a  new 
history  for  the  Lower  Cretaceous  Series  in  England,  that  it  is  quite 
impossible,  with  due  regard  to  other  subjects,  to  do  it  full  justice. 
The  importance  of  the  Speeton  Clay  as  the  fullest  development  of 
marine  beds  of  this  age  in  England  had  been  thoroughly  realized  by 
Prof.  Judd,  who  pointed  out  that  the  section  at  this  place  furnished 
the  key  by  means  of  which  might  be  identified  the  more  or  less 
isolated  and  fragmentary  exposures  of  beds  of  Lower  Cretaceous  age 
scattered  over  the  whole  of  Northern  Europe. 
Many  years  of  careful  attention  to  these  clays,  as  they  are  from 
time  to  time  exposed  on  the  sea-shore,  has  enabled  Mr.  Lamplugh  to 
effect  considerable  alterations  in  the  interpretation  of  the  details  of 
the  section.  Moreover,  in  his  groining  he  has  selected  Belemnites, 
always  abundant  at  Speeton,  rather  than  Ammonites,  as  a  means  for 
defining  his  zones.  Subsequently,  in  association  with  Prof.  Pavlow, 
of  Moscow,  who  inspected  this  section  under  Mr.  Lamplugh’s 
guidance  in  the  autumn  of  1888,  the  Speeton  Clays  have  been  duly 
correlated  with  an  important  series  of  deposits  in  the  interior  of 
Russia,  and  the  rich  palaeontology  of  their  Cephalopoda  largely 
worked  out.1  On  this  point  Prof.  Pavlow  remarks  that  the  Belemnite 
fauna  is  less  rapidly  modified  than  that  of  the  Ammonites,  thus 
enabling  us  to  establish  larger  and  more  generalized  subdivisions  in 
the  manner  already  indicated  by  his  colleague.  On  the  other  hand, 
Ammonites  are  more  sensitive  indicators  of  the  lapse  of  geological 
time. 
Mr.  Lamplugh  considers  that  there  is  a  more  or  less  continuous 
sequence  from  the  clays  of  the  Upper  Jurassic,  through  the  Lower 
Cretaceous  into  the  Upper,  where  at  length  the  argillaceous 
1  ‘  Les  Argiles  de  Speeton  et  leurs  Equivalents,’  par  A.  Pavlow  et  G.  W . 
Lamplugh.  Bull.  Soc.  Imp.  des  Naturalistes,  Moscou,  1892,  vol.  v.  pp.  181-276, 
455-570. 
