PROCEEDINGS O F A N INTERNATIONAL SYMPOSIUM H E L D BY T H E SOUTH
A F R I C A N SOCIETY FOR Q U A T E R N A R Y R E S E A R C H / S W A Z I L A N D /
29 A U G U S T - 2 S E P T E M B E R 1983
ff f > ? X / * ^ K 3
Late Cainozoic
Palaeoclimates of the
Southern Hemisphere
Edited by
J.C.VOGEL
CSIR, Pretoria, South Africa
With the assistance of:
NICOLINE BASSON / U R S U L A V O G E L / A N N E M A R I E FULS
OFFPRINT
A. A.B A L K E M A / R O T T E R D A M / BOSTON
Late Cainozoic palaeoclimates of the Southern
Hemisphere
Proceedings of an international symposium held by
the South African Society for Quaternary Research
in Swaziland, 29 August-2 September 1983
edited by
J.C.VOGEL
CSIR, Pretoria, South Africa
With the assistance of
NICOLINE BASSON, URSULA V O G E L & ANNEMARIE FULS
1984, 25 x 18 cm, 536 pp., 9 photos
Cloth, H f l . H 0 / $40.00 / £ 2 5 . 5 0
Publication date: 26 October 1984
In order to be able to reconstruct what climatic changes
took place in the past, knowledge of the palaeoclimates of
the Southern Hemisphere is of the utmost importance. The
Antarctica and the surrounding oceans play the major role
in regulating atmospheric circulation patterns; even across
the equator. In addition, evidence from deep sea cores has
recently indicated that climatic change in the south actually
preceded that in the northern regions by some 3000 years.
CONTENTS
Palaeoclimatology. Climatic evolution in the Southern Hemisphere
and the equatorial region during the Late Cenozoic (H.Flohn, Univ.
Bonn); A climatic model of the Last Glacial/Interglacial transition
based on palaeotemperature and palaeohydrological evidence (S.P.
Harrison, S.E.Metcalfe & F.A.Street-Perrott, School Geogr., Oxford,
A . B . Pittock, C S I R O , Mordialloc, Australia, C.N.Roberts, Loughborough Univ. Technol. & M.J.Salinger, Univ.East Anglia, U K ) ; etc.
South America. Late Cainozoic glacial variations in South America
south of the equator (J.H.Mercer, Ohio State Univ., Columbus, U S A ) ;
Late Quaternary climates of Chile (C.J.Heusser, New Y o r k Univ.);
Late Glacial glaciation and the development of climate in southern
South America (W.Lauer & P.Frankenberg, Univ. Bonn); etc.
Australasia. New Zealand climate: The last 5 million years ( M . J .
Salinger, N Z Meteorol. Service, Wellington); Glacial age environments of inland Australia (J.M.Bowler, Australian Natl. Univ.,
Canberra & R.J.Wasson, C S I R O , Canberra): Evolution of Australian
landscapes and the physical environment of aboriginal man (J.B.
Firman, Geological Survey, Parkside, S.Australia); etc.
Southern Africa. Late Quaternary environments in S.Africa (K.W.
Butzer, Univ. Texas, Austin); The evidence from northern Botswana
of Late Quaternary climatic change (H.J.Cooke, Univ., Botswana,
Gaborone); Investigations on archaeological charcoals from Swaziland, using S E M techniques (J.Prior, Imperial College, L o n d o n ) ; etc.
The Southern deserts. Ancient ergs of the Southern Hemisphere
(D.S.G.Thomas & A.S.Goudie, Univ. Oxford, U K ) ; Late Quaternary
palaeoenvironments in the desert dunefields of Australia (R.J.Wasson);
A r i d i t y in southern Africa: Age, origins and expression in landforms
and sediments (N.Lancaster, Univ.Cape T o w n ) ; etc.
African faunal record. Horses, elephants and pigs as clues in the
African later Cainozoic (H.B.S.Cooke, Dalhousie Univ., Halifax,
Canada); The Terminal Miocene Event: A critical environmental and
evolutionary episode? ( C . K . B r a i n , Transvaal Museum, Pretoria); etc.
FROM THE SAME PUBLISHER
I S S N 0168-6151
Modern Quaternary research in southeast Asia
(Bartstra,G.-J. & W . A . Casparie, eds.)
1975-, 23 cm, each c.120 pp., Hfl.45 / $18.50 / £10.50
Annual publication. Information on research projects &
results. Bibliographies, plates, maps, figs.
Cresswell, M . M . & P. Vella (eds.)
90 6191088 9
Gondwana five - Selected papers and abstracts ofpapers
presented at the fifth international Gondwana symposium,
Wellington, New Zealand, 11-16 February 1980
1981,25 cm, 352 pp., H f l . 120 / $ 4 8 . 0 0 / £28
The supercontinent which some 180 million years ago
consisted of South America & Africa as 'western*
Gondwanaland and of India, Australia & Antarctica as
'eastern' Gondwanaland. Paleontology & stratigraphy;
Structure & paleogeology; Break-up of Gondwanaland.
D i n e l e , R . V . , W . G . Siesser & A R . Newton
90 6191099 4
Mesozoic and Tertian geologv of southern Africa
1983,28 cm, 385 pp., HÍ1.105 / $39.50 / £24.50
The first book on the latest phase of S. Africa's structural,
sedimentological and igneous development. Based on recently amassed data. Triassic to early Jurassic rocks of the
intracratonic basins; Cape Fold Belt; Middle Jurassic to
Lower Cretaceous; Upper Cretaceous; Tertiary; Mesozoic &
Tertiary igneous activity; References; Indexes.
Ehlers. J ü r g e n (editor)
90 6191 233 7
Glacial deposits in North-West Europe
1983,28 cm, 512 pp., Hfl.dS / $48.50 / £29
Intended as a textbook for students & informed amateurs. &
as a guide for professional geoscientists. The 53 chapters
covering Norway, Sweden, Denmark, Germany & the
Netherlands, are richly illustrated by 409 b / w photos and 95
color photos. Topics covered are; drift prospecting, modern
varve chronology, fine gravel analysis, internal structure o f
thrust moraines, stratigraphical interpretation of well-logs,
echo-sounding of North Sea deposits, erratic pebbles as
indicators, till fabrics, palaeontology of glacial deposits,
multi-component till analyses, glacial deposition on the
continental shelf and the genetic interpretation of glacial
landforms. The regional stratigraphy & glacial chronology of
each of the 5 countries is reviewed. The bibliography
contains 700 entries. Detailed index.
I S S N 0168-6208
Palaeoecologv of Africa - and the surrounding islands
( J . A . Coetzee & E . M . van Zinderen Bakker, eds.)
1966-, 22 cm, c.250 pp., Hfl.75 / $27.50 / £17.50
A n n u a l publication. Comprehensive & up-to-date information on research in many different disciplines which give an
overall insight into the environmental history of Africa.
Volumes 1,2,3 and 5 are out of print.
Anderson, John M . & Heidi M . A n d e r s o n 90 6191 282 2
Palaeoflora of southern Africa: Molteno Formation (Triassic)
A series of six volumes on the Molteno Formation which will
cover the microflora as well as the diverse insect fauna. The
study is based on a collection of 14,000 catalogued slabs from
44 localities. Throughout, taxonomic & phytogeographic
considerations involve the full Gondwana realm, which
makes the publication of interest to palaeontologists from all
pans of the world.
All books available from your bookseller or directly from the publisher:
A.A.Balkema, P.O.Box 1675, NL-3000 BR Rotterdam, Netherlands
A.A.Balkema, P.O.Box 230, Accord, MA 02018, USA
SASQUA international Symposium /Swaziland/29 August - 2 September 1983
Radiocarbon dating of speleothems from the Rössing cave,
Namib desert, and palaeoclimatic implications
K L A U S HEINE
Universität Regensburg, Germany
MEBUS A.GEYH
Niedersächsisches Landesamt für Bodenforschung, Hannover, Germany
ABSTRACT. About 2 km west o f t h e Rössingberge i n t h e Namib d e s e r t a t
a b o u t 340 m above s e a l e v e l , a s m a l l c a v e s y s t e m w i t h s t a l a c t i t e s ,
s t a l a g m i t e s , f l o w s t o n e , p o p c o r n a n d o t h e r s i n t e r f o r m a t i o n s was i n v e s t i g a t e d i n 1978 and 1981. S p e l e o t h e m s have been formed s i n c e t h e T e r tiary.
As t h e cave i s w i t h i n a s m a l l c a t c h m e n t a r e a , t h e s p e l e o t h e m s
r e f l e c t c h a n g i n g p a l a e o h y d r o l o g i c a l and p a l a e o c l i m a t o l o g i c a l c o n d i t i o n s
i n t h e Namib d e s e r t i n t h e v i c i n i t y o f t h e c a v e r a t h e r t h a n t h o s e o f
t h e escarpment i n t h e e a s t .
> A c c o r d i n g t o t h e C14 d a t e s , t h e c l i m a t e a f t e r 41 500 BP c a n be d i v i d ed i n t o f i v e p h a s e s .
U n t i l a b o u t 25 500 BP r a t h e r humid c o n d i t i o n s
p r e v a i l e d as c a v e s i n t e r was f o r m e d .
A f t e r w a r d s t h e c l i m a t e remained
dry i n the study area.
As f r o m 19 000 BP, t h e i n t e r i o r of S o u t h West
A f r i c a a l s o became a r i d .
INTRODUCTION
Some q u e s t i o n s o f t h e L a t e Q u a t e r n a r y c l i m a t i c e v o l u t i o n i n t h e Namib
d e s e r t w i l l be d i s c u s s e d b r i e f l y .
D u r i n g r e c e n t y e a r s many s c i e n t i s t s
have t r i e d t o f i n d e v i d e n c e f o r o r a g a i n s t t h e p e n e t r a t i o n o f h y p o t h e r mal ( G l a c i a l Maximum) w i n t e r r a i n f a l l i n t h e Namib. A c c o r d i n g t o R u s t
and
Schmidt (1981),
f o r example, w i n t e r r a i n f a l l p e n e t r a t e d
as f a r
n o r t h as 20 ° S d u r i n g t h e l a s t p l e n i g l a c i a l .
Van Z i n d e r e n
Bakker
( 1 9 8 3 a , b ) , on t h e o t h e r h a n d , a r g u e d t h a t w i n t e r
rainfall
never
e x t e n d e d so f a r n o r t h d u r i n g t h e L a t e Q u a t e r n a r y .
H i s p o l l e n study
i n d i c a t e s t h a t t h e c l i m a t i c c o n d i t i o n s a t S o s s u s v l e i had n o t changed
s i n c e a t l e a s t 18 000 BP. V o g e l ( 1 9 8 2 ) c o n c l u d e d f r o m d a t e s o b t a i n e d
by h i m on s i l t , c a l c r e t e s , and one wood sample t a k e n a t Homeb on t h e
K u i s e b R i v e r , t h a t t h e l a s t humid p e r i o d i n t h e Namib d e s e r t ended
a b o u t 28 000 BP.
About 2 km w e s t o f t h e Rössingberge ( 1 4 ° 4 8 E, 2 2 ° 3 1 , 5 S) a t 338 m
above s e a l e v e l , a s m a l l cave w i t h a v a r i e t y o f s p e l e o t h e m s r e f l e c t s
t h e c l i m a t i c e v o l u t i o n i n t h e v i c i n i t y o f t h e Rössingberge i n t h e
c e n t r a l Namib d e s e r t .
Two Th230/U234 d a t e s o f s p e l e o t h e m s e x c e e d i n g
300 000 y r s u p p o r t t h e g e o m o r p h i c e v i d e n c e t h a t t h e c a v e and t h e o l d e s t
s i n t e r f o r m a t i o n m i g h t be o f T e r t i a r y o r i g i n .
I n t h i s paper a t t e n t i o n
i s f o c u s e d on t h e L a t e Q u a t e r n a r y o n l y .
S p e l e o t h e m s f r o m a r i d zones c a n be c o n s i d e r e d as " c l o s e d s y s t e m s "
w i t h respect t o carbon isotopes. Therefore,
s u c h s a m p l e s a r e most
f
?
s u i t a b l e f o r C14 d a t i n g .
The c a l i b r a t i o n u n c e r t a i n t y o f t h e d a t e I s
about ± 1000 y e a r s .
I n s p i t e o f t h i s C14 ages seem t o be more r e l i a b l e
t h a n t h o s e o f any o t h e r samples f r o m t h e Namib d e s e r t , s u c h as c a l c r e t e s o r f l u v i a l : l i e s e d i m e n t s w h i c h a r e o f t e n changed d i a g e n e t i c a l l y .
THE CAVE AND PERIODS OF SPELEOTHEM FORMATION
The cave i s s i t u a t e d i n a n a r r o w b e l t o f c a l c a r e o u s r o c k s t h a t emerges
a f e w m e t r e s above t h e o l d Namib d e s e r t s u r f a c e w i t h i n a n a t u r a l c a t c h nient a r e a o f a few km ( F i g . 1 ) . Thus, t h e g r o w t h o f s p e l e o t h e m s was
d e t e r m i n e d by t h e l o c a l p r e c i p i t a t i o n i n t h e v i c i n i t y o f t h e cave o n
the w e s t e r n s l o p e s o f t h e Rössingberge r a t h e r t h a n by t h a t f r o m t h e
escarpment i n t h e e a s t .
The cave c o n s i s t s o f t h r e e chambers s i t u a t e d p a r a l l e l t o t h e NNW/SSE
d i r e c t i o n o f t h e f o l d e d r o c k s i n t h e Namib.
The chambers a r e about
10-20 m b e n e a t h t h e s u r f a c e .
T h e i r w i d t h s range f r o m a few m e t r e s t o
about 15 m, t h e i r l e n g t h s f r o m about 10-25 m. The h e i g h t o f t h e cham-»
b e r s changes f r o m s e v e r a l d e c i m e t r e s t o c. 3 m.
H°45'E
K.Heine 1983
Reference, Main Map
Dry River Bed
=—=—=—
F i g u r e 1.
Railways
Map o f t h e s t u d y a r e a .
^Z*S>Z^ Contour Line
=
Roads
A c c o r d i n g t o t h e g e o m o r p h o l o g i c s i t u a t i o n t h e cave was formed by l i m e
s o l u t i o n or erosion during pre-Pleistocene times.
O n l y a few p o i n t s i n
t h e cave d i s p l a y cave d e p o s i t s as s t a l a c t i t e s , s t a l a g m i t e s , f l o w s t o n e ,
and p o p c o r n . A t p r e s e n t , t h e c a v e a p p e a r s t o be c o m p l e t e l y d r y though
d r o p s of s e e p i n g w a t e r have been o b s e r v e d d u r i n g e x t r e m e l y wet y e a r s .
I n t h e n o r t h e r n p a r t o f t h e c a v e , a huge s t a l a g m i t e ( F i g . 2) s t a n d s
b e n e a t h a b i g f i s s u r e w h i c h a l l o w e d f i n e a e o l i a n sands f r o m t h e Namib
d e s e r t t o e n t e r t h e cave t o g e t h e r w i t h t h e d r i p p i n g w a t e r .
They a r e
f o u n d i n between t h e y o u n g e s t f l o w s t o n e l a y e r s ( F i g . 2) s u r r o u n d i n g t h e
e a s t e r n and s o u t h e r n f l a n k s of t h e s t a l a g m i t e .
Rössing Cave, Namib Desert
F i g u r e 2. S p e l e o t h e m m o r p h o l o g y and s a m p l i n g
ses i n t h e Rössing c a v e .
points for isotope
analy-
The c o n v e n t i o n a l C14 ages o f t h e uppermost f l o w s t o n e l a y e r s ( F i g . 2 )
r a n g e f r o m 37 000 - 26 800 BP. The s p e l e o t h e m s , formed u n t i l about
35 000 BP, c o n s i s t o f m a s s i v e c a l c i t e d e p o s i t s .
L a t e r o n , sand h o r i zons a r e i n t e r c a l a t e d .
The c o n v e n t i o n a l C14 d a t e s
of speleothem
s a m p l e s f r o m o t h e r p l a c e s i n t h e c a v e ( T a b l e 1) a l s o show t h a t s i n t e r
f o r m a t i o n s t e r m i n a t e d a t 26 500 BP. T h i s h o l d s t r u e a l s o f o r t h e popc o r n d e p o s i t s c o n s i s t i n g of i r r e g u l a r l y a l t e r n a t i n g l i g h t and dark
l a y e r s o f a r a g o n i t e and c a l c i t e .
T h e i r f o r m a t i o n began b e f o r e 41 000
BP.
The o u t e r p a r t o f a u n i q u e s t a l a c t i t e c u r t a i n y i e l d e d a d a t e o f
37 000 BP.
O n l y c o n v e n t i o n a l C14 d a t e s have been d i s c u s s e d up t o now.
I t has
b e e n known, however, s i n c e t h e method f o r C14 d a t i n g o f s p e l e o t h e m s was
i n t r o d u c e d by F r a n k e (1951) and p r o v e d t o be a p p l i c a b l e ( F r a n k e e t a l .
1 9 5 8 ) , t h a t a " r e s e r v o i r c o r r e c t i o n " o f a t l e a s t -1000 y e a r s i s n e c e s s a r y t o o b t a i n a c t u a l ages.
L a b e y r i e e t a l . (1967) e v e n f o u n d a c o r r e c t i o n v a l u e of up t o -3500 y e a r s f o r u n c o v e r e d a r e a s .
However, as we
do n o t know t h e g e o e c o l o g i c , p e d o l o g i c and s e d i m e n t o l o g i c s i t u a t i o n i n
t h e Namib d e s e r t a r o u n d 30 000 BP, we a c c e p t V o g e l ' s ( 1 9 8 2 ) c o r r e c t i o n
v a l u e o f -1000 y e a r s f o r o u r g e o c h r o n o l o g i c a l e v a l u a t i o n .
T h i s does
n o t e x c l u d e t h a t t h e r e s u l t i n g t i m e s c a l e may have t o be s h i f t e d f u r t h e r on by up t o -2500 y e a r s .
I n t h i s c a s e , the end of speleothem
f o r m a t i o n m i g h t have c o i n c i d e d w i t h the date
wood f o u n d i.n s i l t s a t Homeb ( V o g e l 1 9 8 2 ) .
of 23 000
BP
obtained
from
Table I.
C o n v e n t i o n a l C14 a g e s , C14 c o n t e n t (pmc) and 6C13
( %o ) f r o m s p e l e o t h e m s of the "Rössing cave In the Namib d e s e r t .
values
Kv
K00
substance
RC age
( y e a r s BP)
RC c o n t e n t
(pmc)
6C13
(%o)
11634
11635
11636
11637
11638
11639
11640
9909
9910
9489
610
613
612
616
619
621
622
162
162a
162(1)
stalagmite
flowstone
flowstone
flowstone
flowstone
stalactite curtain
cave p o p c o r n
cave p o p c o r n
cave p o p c o r n
cave popcorn
26
26
29
33
36
37
41
29
26
26
3.6
3.6
2.4
1.4
1.0
1.0
0.6
2.5
3.6
3.7
-5.4
-7.9
-3.6
-4.0
-5.0
-6.8
-5.3
-4.5
-5.7
-2.0
630
780
830
590
950
000
500
700
700
530
±
+
±
±
±
±
±
±
±
±
500
360
660
1200
1040
1700
1280
1360
540
920
±
±
±
±
±
±
±
±
±
±
0.2
0.2
0.2
0.2
0.1
0.2
0.1
0.4
0.2
0.4
PALAEOCLIMATIC IMPLICATIONS
Our r e s u l t s of r a d i o m e t r i c d a t i n g s t o g e t h e r w i t h s e d i m e n t o l o g i c o b s e r v a t i o n s a t t h e s a m p l i n g s i t e s i n the Rössing cave y i e l d a r a t h e r d i f f e r e n t i a t e d p i c t u r e of the L a t e Q u a t e r n a r y e v o l u t i o n of the c l i m a t e i n
the Namib d e s e r t ( H e i n e 1982). V a r i o u s p h a s e s can be d i s t i n g u i s h e d f o r
the M i d d l e W e i c h s e l i a n p l u v i a l and o t h e r phases o c c u r r i n g up t o the
present.
Once d a t e s of t h e t i m e b e f o r e 41 000 BP become a v a i l a b l e , i t
w i l l be p o s s i b l e t o e l o n g a t e the sequence by c o u n t i n g phases b a c k w a r d s :
PHASE 5:
40 000-34 000
BP
At the end of t h i s p h a s e , the L a s t W e i c h s e l i a n p l u v i a l w i t h compact
s i n t e r f o r m a t i o n t e r m i n a t e d w i t h i n the Namib d e s e r t .
M i s s i n g sand
I n c l u s i o n s i n d i c a t e t h a t a c l o s e d p l a n t c o v e r m i g h t have e x i s t e d .
In
view of the p o p c o r n f o r m a t i o n , the h u m i d i t y must have been h i g h e r t h a n
l a t e r on.
V a r i o u s w a l l c o a t i n g s may d a t e b a c k , however, t o the E a r l y
Q u a t e r n a r y or even t o the T e r t i a r y .
PHASE 4:
34 000-27 000
BP
T h i s phase i s the b e g i n n i n g of t h e a r i d i f i c a t i o n i n the c e n t r a l Namib.
At l e a s t t h r e e n o t i c e a b l e c l i m a t i c f l u c t u a t i o n s o c c u r r e d d u r i n g w h i c h
more humid c o n d i t i o n s were r e p l a c e d by more a r i d ones and v i c e v e r s a .
T h i s i s i n d i c a t e d by i n t e r c a l a t i n g sand l a y e r s w h i c h a c c o u n t f o r a more
windy c l i m a t e and p r o b a b l y not c o m p l e t e l y c l o s e d p l a n t c o v e r .
However,
i t was s t i l l humid enough f o r f o r m a t i o n of compact s i n t e r .
T h i s phase
c o i n c i d e d w i t h the c a l c r e t e f o r m a t i o n on the 40 m t e r r a c e a l o n g t h e
K u i s e b R i v e r ( V o g e l 1982) w h i c h l a s t e d f r o m 33 000 t o 28 000 BP.
PHASE 3:
c . 27 000-25 500 BP
Humid c o n d i t i o n s p r e d o m i n a t e d once more and compact s i n t e r w i t h o u t aeol i a n sand i n c l u s i o n s was f o r m e d .
I t i s n o t known w h e t h e r t h i s was due
t o d e c r e a s i n g w i n d a c t i v i t y o r once more t o a c o m p l e t e l y c l o s e d p l a n t
c o v e r i n t h e Namib d e s e r t . The h u m i d i t y d r o p p e d d r a s t i c a l l y a t t h e end
as p o p c o r n f o r m a t i o n ended.
Phase 3 and 4 may be i d e n t i c a l .
During
t h i s phase t h e r a i n f a l l i n t e n s i t y i n t h e i n t e r i o r i n c r e a s e d and p e b b l e
d e p o s i t s f r o m t h e 40 m t e r r a c e o f t h e K u i s e b R i v e r were removed ( V o g e l
1982).
PHASE 2:
25 000-19 000 BP
From t h i s t i m e onwards t h e Namib d e s e r t r e m a i n e d d r y . No f u r t h e r
s i n t e r f o r m a t i o n o c c u r r e d i n t h e Rössing c a v e .
However, a c c o r d i n g t o
H e i n e ( 1 9 8 2 ) t h e i n t e r i o r of SW A f r i c a was more humid t h a n i t was a f t e r
19 000 BP. I n t h e K u i s e b v a l l e y , dunes s t a r t e d t o b l o c k t h e r i v e r bed
and v l e i s i l t was d e p o s i t e d .
A t t h e end o f t h i s phase t h e a r i d i f i c a t i o n o f t h e Namib d e s e r t was c o m p l e t e (Van Z i n d e r e n B a k k e r 1983a, b ) .
PHASE 1:
a f t e r 19 000 BP
| A c c o r d i n g t o o u r own d a t a f r o m t h e Rössing cave as w e l l as t h e r e s u l t s
of o t h e r p u b l i c a t i o n s m e n t i o n e d a l r e a d y , m a j o r c l i m a t i c f l u c t u a t i o n s no
longer occurred.
The Namib d e s e r t and t h e e a s t e r n escarpment remained
u n d e r a r i d c o n d i t i o n s c o n t r a r y t o t h e a s s u m p t i o n by R u s t and S c h m i d t
( 1 9 8 1 ) t h a t t h e a r e a between 22 a n d 23 ° S had been humid d u r i n g t h e
last Pleniglacial.
One of t h e most i m p o r t a n t f i n d i n g s o f o u r s t u d y i s t h a t one has t o be
c a r e f u l n o t t o t r a n s p o s e c h r o n o s t r a t i g r a p h i c s e q u e n c e s f r o m one a r e a t o
a n o t h e r as d i f f e r e n t p a l a e o c l i m a t i c e v e n t s m i g h t have been r e s p o n s ible.
T h e r e f o r e , c o r r e l a t i o n s between, f o r i n s t a n c e , d i f f e r e n t S o u t h
A f r i c a n s t r a t i g r a p h i e s and t h e i r c o m p a r i s o n w i t h t h e m a r i n e oxygen i s o t o p e r e c o r d c a n o n l y make s e n s e i f a t l e a s t t h e p a l a e o g e o g r a p h i c a l
s i t u a t i o n s are taken i n t o account.
Hence, o u r c h r o n o l o g y o f t h e c l i m a t i c e v o l u t i o n w i t h i n t h e Namib d e s e r t c a n be o f r e g i o n a l iftiportance
only.
Owing t o t h e l o n g h i s t o r y o f t h e Rössing c a v e s i n c e the T e r t i a r y , t h i s c a v e w i t h i t s s p e l e o t h e m s seems t o be one o f t h e most s u i t a b l e p l a c e s f o r r e c o n s t r u c t i n g the p a l a e o c l i m a t i c e v o l u t i o n of the
Namib d e s e r t n e a r 2 2 ° 3 0 S .
f
ACKNOWLEDGEMENTS
We t h a n k Dr GJ H e n n i g , I n s t i t u t für K e r n c h e m i e , Universität Köln, f o r
t h e U/Th age d e t e r m i n a t i o n s o f two s t a l a g m i t e samples and t h e D e u t s c h e
Forschungsgemeinschaft
f o r f i n a n c i a l support.
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