[     188     ] 
XVI.  Proceedings  of  Learned  Societies. 
GEOLOGICAL  SOCIETY. 
[Continued  from  vol.  x.  p.  707.] 
November  8th,  1905.— J.  E.  ITarr,  Sc.D.,  F.R.S.,  President, 
in  the  Chair. 
rPHE  following  communications  were  read  :  — 
1.  '  The  Coast-Ledges  in  the  South- West  of  the  Cape  Colon}*. 
By  Prof.  Ernest  Hubert  Lewis  Schwarz,  A.E.C.S.,  F.G.S. 
The  following  coast-shelves  have  been  recognized  by  the  author 
in  Cape  Colony : — 
Name  of  shelf.        Western.  Midlands.  Eastern.  Sative  Territories. 
Feet.                       Feet,  Feet.  Feet. 
Cyphergat 5000-6000?  5000-6000?  5450?  — 
Sterkstrooin  ...     350(3-4000?               4000?  4406?  4500? 
Kentani 2500  2500 
DeVlugt    1500                      1000  1500  1500 
Uplands 700                        463  467  600 
BamboesBay...        50-100                       200  151  50-200 
Sea-level —                           —  —  — 
Agulhas 600 
The  most  striking  of  these  is  the  Upland  shelf,  which  extends  from 
Caledon  to  Port  Elizabeth.  It  is  cut  by  deep  gorges  into  narrow 
ridges  or  '  ruggens,'  but  at  a  height  the  level  tops  of  these  ridges 
can  be  observed.  The  surface  is  in  places  covered  with  superficial 
deposits,  cemented  boulder  -  deposits,  gravels,  and  sandy  clays, 
hardened  at  the  surface  into  ironstone  or  freshwater  quartzite. 
The  author  considers  that  this  shelf  cannot  have  been  formed  as  a 
peneplain,  but  by  marine  denudation .  On  the  150-to-200-foot  plateau 
there  are  deposits  with  marine  shells,  and  in  a  depression  on  its  top 
the  evaporation  of  rain-water  produces  a  large  quantity  of  salt. 
The  rock-shelf  under  the  Cape  Flats  appears  also  to  have  been  cut 
by  the  sea.  The  Agulhas  Bank  seems  to  consist  of  a  succession  of 
ledges,  but  it  is  not  known  whether  further  shelves  extend  beyond 
its  margin.  Taking  the  ledges  together,  the  continent  would  appear 
to  have  been  subject  to  lifts  of  600  or  700  feet,  with  intermediate 
halts  and  setbacks.  The  author  introduces  the  term  '  absolute 
base-level  of  erosion  '  -  to  express  the  ocean-floor,  including  the  shelf 
or  level  of  erosion  cut  by  the  surf  and  off-shore  currents  that  came 
near  the  water's  edge  when  the  depression  of  the  present  land- 
masses  commenced.'  The  author  compares  the  shelves  of  Cape 
Colony  with  those  described  on  the  European  and  American  sides  of 
the  Xorth  Atlantic,  and  he  places  the  'absolute  base-level  of  erosion' 
at  12,000  feet  in  Xorth  America,  8000  feet  in  Europe,  and  1200  feet 
