10
Radiocarbon Dates for upper Eem and Würm-interstadial samples By H L . DE VRIES, Physical L a b o r a t o r y , U n i v e r s i t y of G r o n i n g e n , N e t h e r l a n d s 1 text-fig. 14
Z u s a m m e n f a s s u n g : Es wird eine Obersicht gegeben von C - D a t e n von Eem-interglazialen und Würm-interstadialen Proben von Loopstedt (Schleswig-Holstein), Amersfoort (Nie derlande), Lebenstedt, Roggendorf, Karrestobel, Geesthacht, Upton Warren (England), Fladbury (England) und von einer Serie von Holzkohle-Proben aus den Lößgebieten. Sogar die jüngsten Eem-Proben zeigten keine signifikante Aktivität (Alter mehr als 53 000 Jahre). Die Daten stellen das Interstadial Würm I I / I I I (fossiler Boden von Paudorf) auf rund 26 000 Jahre vor heute. Die Daten für das Interstadial I/II sind noch teilweise unzuverlässig, weil Verunreinigung mit rezentem Material (Wurzeln, Humus) für diese alten Proben relativ viel für die totale Aktivität beiträgt. Obwohl die Periode zwischen 33 000 und 42 000 Jahren (vor heute) ziemlich kalt war, ist es nicht unmöglich, daß es sich hier um das Interstadial W I/II handelt. Ein wärmeres Interstadial endete vor ungefähr 48 000 Jahren. Die Daten stimmen mit EMILIANIS Paläotemperaturkurve (und MILANKOVITCHS Zeitskala) überein. S u m m a r y : Radiocarbon dates have been obtained for Eem-interglacial and Würm-inter stadial sections from L o o p s t e d t (Germany) and A m e r s f o o r t (Netherlands), for a few isolated peat samples from North-Western Europe and for charcoal samples from Austrian loess regions. Even the upper part of the Eemian proved to be too old to give a significant activity (age more than 53000 years). According to the present results the interstadial Würm I I / I I I (fossil soil of P a u d o r f ) occurred at about 26000 years ago. Because of various contaminations of the samples (infiltrated humus, rootlets etc.) the results for the interstadial Würm I/II are somewhat controversial, but it is not impossible that it should be identified with the fairly cool period between 33 000 and 42 000 before present. A somewhat warmer interstadial ended about 48 000 years ago. The results fit well with EMILIANIS paleotemperature curve. 1 The
measurements
T h e measurements described below w e r e m a d e in o u r large counter. T h e net count for recent carbon is 36.9 per m i n u t e . T h e present b a c k g r o u n d is 2.4 per m i n u t e . I t varies 0.05/min for a v a r i a t i o n in b a r o m e t e r pressure of 1 cm H g . F o r details see (1,2). In t h e calculations a half life of C of 5570 years has been used. T h e error given is the s t a n d a r d d e v i a t i o n ; it includes the error in the background as well as the error in t h e sample c o u n t . Since the background, corrected for b a r o m e t e r effect, w a s very c o n s t a n t , several back g r o u n d measurements could be a v e r a g e d . This leads to a relatively small error in t h e background. T h e dates given represent the average result of a t least t w o measurements, which, as a rule, are n o t r e p o r t e d s e p a r a t e l y . 1 4
O u r measurements of old samples h a v e d e m o n s t r a t e d the i m p o r t a n c e of an a p p r o p r i a t e p r e t r e a t m e n t , developed to r e m o v e infiltrated o r g a n i c m a t e r i a l . A l l samples w e r e boiled first w i t h a one per cent solution of hydrochloric acid. After w a s h i n g w i t h distilled w a t e r they w e r e heated a t least one n i g h t at 90° C w i t h o n e per cent sodium h y d r o x y d e . T h e sample w a s w a s h e d then, one p e r cent hydrochloric acid added, h e a t e d again a n d w a s h e d u p to a p H of 4 or m o r e . T h e e x t r a c t e d h u m u s w a s precipitated w i t h hydrochloric acid, washed a n d dried. Before considering the dates o b t a i n e d , the i n d i v i d u a l samples will be discussed. d e V o o r s t , N o r t h E a s t e r n P o l d e r (former Zuidersee). T h i s series of samples w a s collected from a well exposed section of the E e m i a n a t de V o o r s t (3). Dates f r o m 43000 to "infinite" were o b t a i n e d f r o m samples b e t w e e n the beginning of the climatic o p t i m u m of the E e m Interglacial a n d the end of the Riss Glacial. T h e samples have been
Radiocarbon dates
11
m e a s u r e d several times in a period of a b o u t one y e a r a n d a half (4,5). I n t h a t period the b a c k g r o u n d of the c o u n t e r a n d its v a r i a t i o n w i t h b a r o m e t r i c pressure has been reduced a p p r e c i a b l y (1,2). T h o u g h the later measurements w e r e m o r e accurate, all results agreed. So t h e dates h a d to be a c c e p t e d as far as the r a d i o c a r b o n measurements w e r e concernced, b u t the much older dates o b t a i n e d for the samples presented below p r o v e t h a t the samples f r o m d e V o o r s t h a d been c o n t a m i n a t e d b y y o u n g m a t e r i a l . T h e n a t u r e of the c o n t a m i n a t i o n is u n k n o w n . W h a t e v e r the origin m a y be, t h e present samples a r e a p r i o r i m o r e reliable since t h e y come from layers covered b y a t least 2.5 meters of sand a n d other deposits, whereas the profile a t d e V o o r s t h a r d l y h a d a n y p r o t e c t i n g layers a t all. L o o p s t e d t , N o r t h - W e s t e r n G e r m a n y , close to the t o w n of S c h l e s w i g . T h e profile a t L o o p s t e d t is well k n o w n . T h e present samples came from the southern side of the lake; t h e y w e r e submitted by Professor SCHWABEDISSEN ( K ö l n ) . N e w pollend i a g r a m s have been p r e p a r e d b y D r . KOLUMBE (6). T h e y were p u t a t o u r disposal a l r e a d y before publication. T h e dates obtained w e r e : sample d depth a b o u t 4.5 metres G R O 1254 age > 53000 sample e depth 3.65 m 1242 age 39800 ± 1000 GRO sample / 1234 age 37630 ± 1000 depth 3.00 m GRO sample g 1270 age 37050 ± 500 GRO depth 2.40 m sample g 1290 age 35400 ± 400 GRO sample G 1329 age 45300 ± 2000 GRO sample G 1337 age 45300 ± 2000 GRO a
a
A l l samples h a v e been measured at least twice, b u t only the a v e r a g e value has been given since the results agreed w i t h i n the limits of e r r o r . Sample d represents the t o p of the E e m i a n , samples e-g a r e assigned to the i n t e r s t a d i a l W ü r m I / I I . T h e p e a t layers e-g w e r e embedded in s a n d ; the deposits on t o p of g w e r e also sand. S a m p l e g is identical w i t h g, b u t it has n o t been treated w i t h a l k a l i ; consequently it could c o n t a i n infiltrated ( y o u n g e r ) humus. T h e difference measured, though it is n o t very large, m a y be ascribed to this effect. W e supposed the result for g to be reliable, b u t on a visit to L o o p s t e d t , together with D r . ANDERSEN ( K o p e n h a g e n ) , D r . KOLUMBE ( H a m b u r g ) a n d Prof. WATERBOLK (Groningen), it w a s observed t h a t the layers e-g certainly c o n t a i n e d recent roots which w e r e not r e m o v e d b y the chemical t r e a t m e n t . T h e r e f o r e n e w samples were collected, f r o m which the roots w e r e r e m o v e d b y a special mechanical m e t h o d . P a r t of the roots w e r e collected, a n d this a m o u n t w a s a l r e a d y large e n o u g h to account for a t least one half of t h e activity of s a m p l e g. After this mechanical t r e a t m e n t the sample w a s given the n o r m a l chemical t r e a t m e n t ; the m a t e r i a l left w a s d a t e d (sample G ) . P a r t of the e x t r a c t e d h u m u s (the less mobile fraction) w a s also d a t e d ( s a m p l e G ) . F o r t h e present purpose w e need only consider sample G ; the d a t e o b t a i n e d demonstrates well enough t h a t the a c t u a l age of the i n t e r s t a d i a l is much higher t h a n 40000. a
a
R e c e n t l y the a u t h o r has collected charcoal from a sand lens in the u p p e r p e a t layer (g). I t w a s carefully e x a m i n e d u n d e r the microscope; n o n e of the pieces c o n t a i n e d rootlets. A c c o r d i n g to D r . W . VAN ZEIST ( p r i v a t e discussion) the vessels of coniferous w o o d are g e n e r a l l y too small even for the finest r o o t h a i r s . N o charcoal from b r o a d - l e a v e d trees w a s present. L o o p s t e d t g, charcoal G r o 1365 age 50000 ± 2000 W i e r d e n a n d E e f d e , p r o v i n c e of Overijsel a n d G e l d e r l a n d , N e t h e r l a n d s . F r o m o p e n pits, well b e l o w g r o u n d w a t e r level, Prof. FLORSCHÜTZ collected well preserved w o o d . B y the species f o u n d (for W i e r d e n see 3) t h e climate c o u l d be identified as pleniglacial. Wierden G r o 1359 age 38100 ± 500 Eefde G r o 1367 age 33070 ± 300
12
Hl. de Vries
T o g e t h e r w i t h these samples the d a t e for another pleniglacial sample ( B r e d a , G r o 936, age 32000 ± 900) should be m e n t i o n e d . F o r details see (5). A m e r s f o o r t ( N e t h e r l a n d s ) . As m i g h t be well k n o w n , the vicinity of A m e r s f o o r t (the Eem-valley) has p r o v i d e d t h e t y p e locality of the E e m i a n Interglacial Stage ( N o r t h A m e r i c a n S a n g a m o n ) . T h o u g h d u r i n g the last 50 years m a n y bailer borings h a d been m a d e here, which did reach the E e m i a n deposits, no reliable well sampled borings from this locality were available. G u i d e d by the d a t a previously o b t a i n e d , D r . ZAGWIJN ( N e therlands Geological Survey) executed a n u m b e r of new borings, which were s a m p l e d as detailed as possible by a special coring a p p a r a t u s . F u r t h e r m o r e samples w e r e o b t a i n e d from an e x c a v a t i o n a t Amersfoort, some eight meters deep, d u g in purpose for the con struction of a tunnel below a r a i l r o a d crossing. T h e full discussion of the results o b t a i ned a t this section a n d the borings will be published in due course; the v a r i o u s investi gations are still carried on a t this m o m e n t . T h e geological a n d p o l l e n a n a l y t i c a l d a t a obtained by ZAGWIJN can shortly be s u m m a rised as follows. Between the E e m Interglacial a n d w h a t is i n t e r p r e t e d as W ü r m I in fig. 1, there is a t least one „ i n t e r s t a d i a l " which m a y , perhaps, be c o r r e l a t e d w i t h the h u m p at 80000 years in fig. 1 (EMTLIANI'S time scale). I t is of interest to n o t e t h a t BRANDTNER (7) finds t w o interstadials between W ü r m I a n d Eem. W h a t e v e r t h e correlation m a y be, the age of these interstadials is m o r e t h a n 53000 years (Amersfoort X I I a n d X I V ) . Amersfoort X I I ( w o o d ) GRO 1248 GRO 1252 GRO 1257 > 53000 GRO 1268 Amersfoort X I V ( w o o d ) GRO 1280 > 53000 GRO 1285 Amersfoort X I (peat) GRO 1259 age 34730 ± 700 GRO 1276 age 3 4 7 3 0 ± 500 Amersfoort X I extracted h u m u s GRO 1106 age 2 0 4 7 0 ± 230 Sample X I I came from the first interstadial (?) above the E e m . Sample X I V was y o u n g e r t h a n sample X I I . F o u r p e a t samples from the s a m e period a b o v e the Eem also gave ages m o r e t h a n 53000. T h e o n l y „recent" sample obtained u p to n o w in A m e r s f o o r t was A m e r s f o o r t X I , originating from the pit, from a highly k r y o t u r b a t e l o a m y p e a t layer; the pollenspectrum pointed to a v e r y cold climate (Pleniglacial). T h o u g h the sample w a s covered b y a b o u t four meters of sand, infiltration of y o u n g h u m u s was suspected. T h e r e f o r e h u m u s w a s carefuly extracted. T h e d a t e of sample X I refers to the r e m a i n i n g material. T h e h u m u s is a p p r e c i a b l y m o r e active t h a n the rest of t h e sample. T h i s m e a n s t h a t p a r t of t h e h u m u s has infiltrated, p r o b a b l y from the A l l e r ö d layer which was well developed a b o u t 70 cm u n d e r the present surface. Since the N a O H - t r e a t m e n t w a s v e r y rigorous, the result obtained for sample X I ist p r o b a b l y reliable. F a r m s u m , 40 k m N o r t h E a s t of Groningen, N e t h e r l a n d s . T h e p e a t l a y e r w a s separated b y a b o u t one m e t e r of sand from 7000 years o l d p e a t , which w a s covered w i t h clay. F a r m s u m II a ( u p p e r side of peat) GRO 1278 age 33300 ± 400 F a r m s u m II GRO 1279 age 37900 ± 1000 H u m u s from II GRO 1133 age 2 9 9 8 0 ± 500 F a r m s u m I a (lower side of peat) GRO 569 age 35860 ± 1000 Farmsum I GRO 1324 age 4 3 7 0 0 ± 700 T h e samples m a r k e d w i t h a h a d been given o n l y an H C l t r e a t m e n t ; they are a p p r e c i a b l y younger b y infiltration of y o u n g humus. T h e extracted m a t e r i a l also contains h u m u s of
Radiocarbon dates
13
t h e sample itself b u t the low age of the humus f r a c t i o n indicates t h a t m o r e or less selec tively, infiltrated, m o r e mobile, m a t e r i a l has been e x t r a c t e d . Because of the large a m o u n t of infiltrated m a t e r i a l it is n o t possible to claim t h a t it has been r e m o v e d completely. So t h e p e a t m a y still b e older t h a n 4 3 7 0 0 years. T h e p o l l e n d i a g r a m does n o t exclude t h a t t h e sample is late E e m , b u t it m a y also be c o r r e l a t e d with Loopsted e-g. Because of these uncertainties this p e a t layer will n o t be considered in the discussion (2). T h e samples w e r e collected by W . ZAGWIJN (Geological Survey, H a a r l e m ) w h o also m a d e the p o l l e n diagrams. G e e s t h a c h t , n e a r H a m b u r g ( G e r m a n y ) . D u r i n g e x c a v a t i o n s in 1955 a good profile was o b t a i n e d from which several samples w e r e taken b y D r . SCHÜTRUMPF. T h e samples from w h a t w a s p r o b a b l y E e m were n o t studied since t h e y w o u l d be t o o old. A t depths of a b o u t 5 a n d 6 meters respectively, n u m i n o u s layers w e r e found which w e r e p r e l i m i n a r y ascribed to Alleröd a n d Bölling. I n o u r l a b o r a t o r y w e f o u n d some charcoal in t h e u p p e r sample which is typical for the end of t h e Alleröd in the N e t h e r l a n d s ; the r a d i o c a r b o n date also confirms this assignment (sample I I ) , though t h e age is s o m e w h a t t o o l o w . T h i s m a y be the correct d a t e b u t the date m a y also h a v e been affected by a small infiltration of recent humus since the humus c o n t e n t was very l o w . Sample I I I t u r n e d o u t to be much o l d e r t h a n Bölling; it is synchronous w i t h the fossil soil of P a u d o r f (see discussion). Because of the s t r a t i g r a p h y , a n d because of the f a i r l y young age of the s a m p l e , the date of I I I can h a r d l y be affected by infiltration of recent material. Geesthacht I I , coarse sand, c o n t a i n i n g a b o u t 1 p e r cent of h u m u s G r o 1507 10150 ± 80 Geesthacht I I I , l o a m y sand w i t h humus G r o . 1515 26600 ± 300 T h e sand b e t w e e n I I a n d I I I c o n t a i n e d a l a y e r of stones („Windschliff"). I n a discus sion D r . DÜCKER (Kiel) pointed o u t t h a t this is t y p i c a l for W ü r m I I I a t the present site; this agrees very well w i t h the dates obtained. U p t o n W a r r e n a n d F 1 a d b u r y (near B i r m i n g h a m , E n g l a n d ) . These samples w e r e submitted b y Prof. SHOTTON of B i r m i n g h a m . T h e y consisted of organic m a t e r i a l in a layer of l o a m y s a n d in a gravel p i t ; the organic material w a s s e p a r a t e d from t h e sand by passing the s a m p l e over a sieve which t r a n s m i t t e d the sand. B o t h samples are r e g a r d e d on geological g r o u n d s as of similar age, both being associated w i t h the retreat of the „Irish Sea Glacier", which is itself fixed by the t e r r a c e chronology as the first glaciation following the E e m interglacial. T h e U p t o n W a r r e n sample dates f r o m a period s h o r t l y after the m a x i m u m of the ice leading t o w a r d s t h e interstadial which is generally c o r r e lated with W ü r m I / I I . Upton Warren a GRO 595 age 41500 ± 1200 Upton Warren G R O 1245 age 41900 ± 800 Extracted humus G R O 1063 age > 40000 Fladbury G R O 1269 age 38000 ± 700 Sample U p t o n W a r r e n a w a s d a t e d w i t h a c i d p r e t r e a t m e n t o n l y ; since the d a t e o b t a i n e d is essentially the same as after c o m p l e t e p r e t r e a t m e n t a n d since the e x t r a c t e d h u m u s was also o l d , infiltration of recent humus is i m p r o b a b l e . C h e l f o r d ( E n g l a n d ) . T h o u g h the correlation w a s n o t u n a m b i g u o u s , it w a s s u p posed that this s a m p l e w a s c o r r e l a t e d to L o o p s t e d t e-g; the e v i d e n c e w a s obtained f r o m pollenanalysis. T h e sample was collected by D r . R . WEST ( C a m b r i d g e ) w h o also m a d e t h e pollenanalysis; it w a s s u b m i t t e d by Prof. WATERBOLK ( G r o n i n g e n ) . T h e sample consisted of well p r e s e r v e d w o o d . T h e result w a s GRO 1292 age > 53000 L e b e n s t e d t ( n e a r Braunschweig, Niedersachsen, G e r m a n y ) , collected by D r . TODE, submitted by Prof. SCHWABEDISSEN, K ö l n . T h e sample consisted of gyttja a n d h u m u s .
Hl. de Vries
14
T h e sample preceded a very cold period which is p r o b a b l y W ü r m I. F o r further details see discussion a n d ( 8 ) . Lebenstedt
GRO
1219
age 4 8 3 0 0 ±
2000
S e n f t e n b e r g (Austria). S a m p l e of charcoal, submitted b y D r . BRANDTNER ( V i e n na.) I t was f o u n d under a fossil soil identified b y BRANDTNER as t h e interstadial W ü r m I / I I (Götrweig fossil soil). Senftenberg
GRO
1217
age 4 8 3 0 0 ±
2000
R o g g e n d o r f (Austria). Collected a n d submitted b y BRANDTNER ( V i e n n a ) , from a p e a t layer which was supposed t o represent t h e interstadial W ü r m I / I I (see 9 ) . O n t o p of t h e layer considered here (thickness a b o u t 1 meter) s e c o n d a r y m a t e r i a l w a s f o u n d , even t e r t i a r y pollen. Infiltration of recent m a t e r i a l , including r o o t s , w a s n e a r l y i m p o s sible. u p p e r side of peat lower side
,
G R O 1 3 0 1 age 7 7 6 0 ± 1 2 0 G R O 1 1 9 8 age 1 1 4 0 0 ± 9 0
Obviously t h e p e a t is of holocene a n d late-glacial age; according t o Prof. WATERBOLK, Groningen, ( p r i v a t e discussion) t h e p o l l e n d i a g r a m could fit w i t h t h e present dates. A m o r e d e t a i l e d discussion will be given b y BRANDTNER. P o l l a u ( M o r a v i a , Tschechoslovakia). C h a r c o a l from G r a v e t t i a n settlement, just above t h e „ P a u d o r f " fossil soil. S a m p l e a w a s submitted b y Prof. SCHWABEDISSEN ( K ö l n ) a n d collected b y D r . KLIMA. S a m p l e b w a s submitted by D r . BRANDTNER (Vienna). Since KLIMA ( 1 0 ) h a d shown t h a t in this region sometimes fossil fuel h a d been used even a t t h a t time, BRANDTNER suggested t o use a sample (b) consisting of carefully selected charcoal. Since P o l l a u a (which w a s d a t e d first) is older t h a n both P o l l a u b a n d U n t e r w i s t e r n i t z (see below) it is n o t i m p r o b a b l e t h a t sample a h a s contained some fossil carbon. Pollau a Pollau b
GRO GRO
1 2 7 2 age 2 6 4 0 0 ± 2 3 0 1 3 2 5 age 2 4 8 0 0 ± 1 5 0
U n t e r w i s t e r n i t z ( M o r a v i a , Tschechoslovakia). C h a r c o a l from G r a v e t t i a n settlement in u p p e r half of t h e „ P a u d o r f " fossil soil. Submitted b y Prof. SCHWABEDISSEN from older excavations b y ABSOLON. Unterwisternitz
GRO
1 2 8 6 age 2 5 6 0 0 ± 1 7 0
A g g s b a c h (Austria). C h a r c o a l from G r a v e t t i a n settlement ( " E a s t e r n G r a v e t t i a n " ) , collected b y BRANDTNER in 1 9 5 7 . Aggsbach a Aggsbach b
GRO GRO
1 3 2 7 age 2 2 4 5 0 ± 1 0 0 1 3 5 4 age 2 5 5 4 0 ± 1 7 0
T h e d a t e e x p e c t e d b y BRANDTNER w a s a b o u t 3 0 0 0 0 years, i. e. e q u a l to W i l l e n d o r f (see below). Since sample a, which h a d been given t h e n o r m a l p r e t r e a t m e n t , came o u t much younger t h a n anticipated, a n o t h e r p a r t of t h e sample was given a n extra t r e a t m e n t b y which also r o o t s w o u l d be r e m o v e d completely. S a m p l e b is still " t o o y o u n g " . M o r e o v e r it is h a r d t o believe that t h e difference between a a n d b is due t o t h e removal of r o o t l e t s , since h a r d l y a n y rootlets w e r e seen in t h e s a m p l e , n o r a t t h e site of t h e e x c a v a t i o n , whereas sample a should h a v e c o n t a i n e d 2 p e r cent (by weight) of roots in o r d e r t o e x plain t h e difference. T h e difference m a y also be d u e to an i n h o m o g e n e i t y of t h e s a m p l e . W i l l e n d o r f (Austria). C h a r c o a l from A u r i g n a c i a n settlement. By a m i s t a k e in the museum, sample 7 w a s o r i g i n a l l y assigned t o t h e same site as t h e sample from l a y e r 4 . Recently i t w a s found t h a t 7 c a m e from a n o t h e r site (Willendorf I instead of W i l l e n dorf I I ) . I t corresponds t o a b o u t culture layer 7 in t h e site I I . A c c o r d i n g to BRANDTNER ( p r i v a t e c o m m u n i c a t i o n ) s a m p l e 4 should be assigned to a s t a d i a l , whereas sample 7 is s o m e w h a t y o u n g e r . Willendorf 4 w a s submitted b y Prof. SCHWABEDISSEN a n d collected by
Radiocarbon dates
15
F e l g e n h a u e r in 1954. W i l l e n d o r f 7 w a s submitted b y BRANDTNER from a n o l d e r excavation b y OBERMAIER a n d BAYER; it w a s carefully checked t h a t it did n o t c o n t a i n fossil coal. Willendorf 4 Willendorf 7
GRO GRO
1273 1287
age 31840 ± 2 5 0 age 30310 ± 2 5 0
I s t a l l ö s k ö - c a v e ( H u n g a r i a , B ü k k m o u n t a i n s ) . C h a r c o a l f r o m typical A u r i g n a c i a n settlement. (Details can be f o u n d in 11 u. 12). T h e charcoal c o n t a i n e d some recent w o o d splinters a n d seeds. Therefore o n l y good pieces of charred w o o d w e r e selected; t h e sample obtained in this w a y did n o t c o n t a i n e n o u g h c a r b o n even for the medium size c o u n t e r . I t was o n l y given an acid p r e t r e a t m e n t since infiltration of h u m u s was i m p r o b a b l e ; alkali t r e a t m e n t w o u l d have r e m o v e d an i m p o r t a n t p a r t of t h e small sample. T h e sample was collected b y D r . VERTES a n d submitted b y Prof. SCHWABEDISSEN. Istallöskö-cave
GRO
15C1
age 30670 ± 500
So it is h a r d l y older t h a n the A u r i g n a c i e n from Willendorf. I t is assigned to the i n t e r stadial W ü r m I / I I . K a r r e s t o b e l b . Baindt (Kreis R a v e n s b u r g , W ü r t t e m b e r g , G e r m a n y ) . T h e sample c a m e from a p e a t l a y e r in the W ü r m m o r a i n e (see 13). F u r t h e r studies are required t o come to a more d e t a i l e d assignment; t h e d a t e o b t a i n e d suggests t h a t the present sample comes from the i n t e r s t a d i a l W ü r m I I / I I I . A t the same locality a b o u t six peat layers occur. T h e sample w a s submitted b y D r . H . GROSS, B a m b e r g . Karrestobel
GRO
1277
age 28840 ± 300
2 Discussion T h e series of samples between a b o u t 25000 a n d 31000 years is very consistent, p r o b a b l y since recent c o n t a m i n a t i o n has not yet such a large effect as for samples which a r e m o r e than 40000 years old. T h e d a t e s for P o l l a u a n d U n t e r w i s t e r n i t z fix the end of the formation of the fossil soil of " P a u d o r f " at a b o u t 25000. N o n e of the samples m a r k s the beginning of this p e r i o d ( W ü r m 11/111) unless K a r r e s t o b e l (29000) could be taken for this. Willendorf was a l r e a d y older t h a n the beginning of the P a u d o r f soil. Considering EMILIANI'S p a l e o t e m p e r a t u r e curve (14) there is no d o u b t t h a t this i n t e r s t a d i a l corresponds to the short a n d l o w m a x i m u m at 28 000 in fig. 1. Since mixing processes a t the b o t t o m of the ocean tend to flatten out short p e a k s , the a c t u a l duration of the formation of t h e P a u d o r f soil was p r o b a b l y much shorter. T h e thickness of the soil also points to a fairly s h o r t interstadial. T h e older dates offer more p r o b l e m s . T h e dates for Breda, Eefde, Amersfoort X I a n d W i e r d e n suggest t h a t it has been c o l d from the P a u d o r f interstadial u p to at least 38000 years ago, w h e r e a s the results for F l a d b u r y a n d U p t o n W a r r e n , w i t h their cold f a u n a , allow to e x t e n d the cold period u p to at least 42000 years a g o . T h e cold climate is n o t compatible w i t h the p o l l e n d i a g r a m for F a r m s u m ; this s u p p o r t s the conclusion a l r e a d y arrived a t t h a t the dates for F a r m s u m are n o t reliable. M o r e o v e r a new p o l l e n d i a g r a m from the same p i t gave m o r e conclusive evidence t h a t the original assignment to late E e m was correct. T h o u g h the p e r i o d between 33 000 and 42 000 w a s cold in N o r t h W e s t e r n Europe, it w a s p r o b a b l y n o t as cold as, say, during the p e r i o d between 24 000 a n d 12 000; from this period no o r g a n i c material a t all was r e c o v e r e d u p to n o w in N o r t h Western E u r o p e . Since W i l l e n d o r f a n d Istalloskö-cave ( a b o u t 30 000) are p r o b a b l y not much y o u n g e r than the so called G ö t t w e i g interstadial, this interstadial c o u l d well be correlated w i t h the period b e t w e e n 33 000 a n d 42 000. A c c o r d i n g to D r . BRANDTNER ( p r i v a t e discussion) the G ö t t w e i g interstadial w a s fairly cool a n d so it is not i m p o s sible t h a t it is synchronous with the c o l d e r period f u r t h e r n o r t h .
16
Hl. de Vries
T I M E ( x 1000 years)
Fig. 1. Paleotemperature curve (from EMILIANI, 14). Upper time scale from EMILIANI. Lower time scale, up to 50 000 years according to C dates. The group of samples around 40 000 was not reliable, however (see text), and EMILIANIS scale may be correct. N o t all samples around 26 000 have been inserted (by points). 1 4
T h e n e x t dates to be considered are Senftenberg, Lebenstedt a n d Loopstedt G (char coal). L o o p s t e d was correlated b y its p o l l e n d i a g r a m to the n e w d i a g r a m of B r ö r u p (ANDERSEN, 15). A short r e p o r t o n the B r ö r u p dates is in p r e p a r a t i o n (16); for t h e present discussion it is sufficient to state t h a t all dates obtained w e r e " m o r e t h a n 53 0 0 0 " . This does n o t e x c l u d e t h a t L o o p s t e d G m a y be a r o u n d 50 000 since t h e u p p e r i n t e r s t a d i a l in Loopsted is s o m e w h a t m o r e complete t h a n in Brörup. N e w borings by D r . ANDERSEN gave a m o r e complete sequence. P r e l i m i n a r y measurements of t h e end of this interstadial gave 48 000 years, in a g r e e m e n t w i t h the L o o p s t e d t date. A c c o r d i n g to the references given Lebenstedt m a r k s t h e beginning of a cold period; its d a t e p u t s it nicely a t the end of the B r ö r u p interstadial. I t is obvious t h a t Senftenberg (48 000 years) does n o t fit a t all since it was supposed t o date the e n d of a stadial ( W I). T h e charcoal was deposited in the loess before the G ö t t w e i g - w e a t h e r i n g o c c u r r e d (comment b y D r . BRANDTNER). Its age (48 000) p u t s it at the end of a n i n t e r s t a d i a l ; obviously this discrepancy c a n n o t be r e m o v e d b y constructing a n o t h e r set of stadials a n d interstadials a n d a new m e a s u r e m e n t will be p e r f o r m e d if new m a t e r i a l comes a v a i l a b l e (see note p . 17). If the G ö t t w e i g is correlated w i t h the B r ö r u p interstadial instead of the colder period between 33 000 and 42 000, some difficulties arise about the „ v a c u u m " created t h e n bet ween the e n d of this i n t e r s t a d i a l a n d the age of the layers just o n top of the G ö t t w e i g soil (Willendorf, 30 000), even if geological evidence in s u p p o r t of the assignment sug gested a b o v e is neglected. T h i s assignment, h o w e v e r , also needs reconsideration of various views. I t implies t h a t W I o c c u r r e d between 48 000 a n d a b o u t 42 000. ANDERSEN (1. c.) has p u t this stadial before the B r ö r u p i n t e r s t a d i a l . (See also fid. 1). W I I w o u l d n o w be a r o u n d 30 0 0 0 (if this n o m e n c l a t u r e is still a c c e p t e d a t all). T h e climatic history, n o w a r r i v e d at, fits w i t h EMILIANI'S p a l e o t e m p e r a t u r e curve (fig. 1). I t presents the same, q u a l i t a t i v e , course of the t e m p e r a t u r e and, m o r e o v e r , the timescale agrees with the conclusions d r a w n in the present discussion. I t is obvious that the first r e q u i r e m e n t for further w o r k is t o collect reliable samples, if possible from continuous, well exposed profiles. T h e p r e s e n t r e p o r t demonstrates clearly t h e i m p o r t a n c e of infiltration of recent material, a n d this will become e v e n worse for samples older t h a n W ü r m I. Recently o u r a p p a r a t u s was i m p r o v e d so far t h a t samples u p to 70 000 years can be d a t e d ; these samples should contain a t least 500 gram of carbon, however.
Radiocarbon dates
17
A c k n o w l e d g e m e n t s . I a m greatly i n d e b t e d to all submitters of samples, w h o also contributed t o t h e c o m m e n t s . T h e y will g i v e m o r e complete discussions in d u e course. V e r y stimulating has been t h e nearly d a i l y c o n t a c t with D r . ZAGWIJN ( H a a r l e m ) a n d Prof. WATERBOLK ( G r o n i n g e n ) .
References: 1. H l . DE VRIES: Nucl. Phys. 1, 477, 1956. 2. H l . DE VRIES: Nucl. Phys. 3 , 65, 1957. 3. I. M. VAN DER VLERK & F . FLORSCHÜTZ: Verh. Kon. Ak. Wet. afd. Natuurkunde le reeks X X ,
4.
18, 1953. G. W. BARENDSEN: Thesis Groningen 1955.
5. 6. 7. 8.
H l . DE VRIES et al.: Science 1 2 7 , 129, 1958. E. KOLUMBE: Eiszeitalter u. G. 6, 39, 1955. F . BRANDTNER: in preparation. A. T O D E : Eiszeitalter u. G. 3 , 144, 1953.
9. F . BRANDTNER: Arch. Austriaca 2 , 5, 1949. 10.
B . KLIMA: Antiquity 3 0 , 98, 1956.
11.
L. VERTES: Acta Arch. Scient. Hung. 5, 111, 1955; Quartär 8, 1957.
12. H . SCHWABEDISSEN: Germania 3 4 , 18, 1956. 13. A. PENCK & E . BRÜCKNER: Die Alpen im Eiszeitalter 2 , 422, 1909. 14. C. EMILIANI: J. Geol. 6 3 , 538, 1955. 15. S. T. ANDERSEN: Eiszeitalter u. G. 8, 181, 1957. 16. H . TAUBER & H l . DE VRIES: Eiszeit u. Geg. 9, 1958.
Manuskr. eingeg. 3. 10. 1957. Anschrift des Verf.: Prof. Dr. Hl. de Vries, Natuurkundig Laboratorium der Rijks-Universiteit te Groningen (Niederlande), Westersingel 34.
N o t e a d d e d i n p r o o f . Recently the author saw some of the charcoal from Senftenberg still embedded in the loess (brown earth). The soil contained a large amount of recent rootlets. This means that the discrepancy between Senftenberg and the other samples mentioned above is probably due to recent contamination. A fraction of 0.2 per cent recent material is sufficient to produce the activity found. Then the actual age of the sample would be much higher. This also implies that the Göttweig soil would have to be correlated with the Brörup interstadial, but more conclusive samples will be dated in the near future.
2
Eiszeit und G e g e n w a r t