54
D A R I I ' S Z KRZYSZKOWSKI
ioo-
coutour lines m a s I
distinct scarps
I sites with the Wirtanian till
Fig. 1: L o c a t i o n o f t h e S i e d l e c S a n d u r
forested areas on the sandur
WartQnion sandurs lolluvial fans)
s o u t h w a r d s t h e T r z e b n i c a Hills.
2 G e o l o g y o f t h e T r z e b n i c a Hills a n d i t s southern foreland 2.1 H i s t o r i c a l b a c k g r o u n d
At t h e s a m e time, there w a s discussion o n g e n e s i s o f the N e o g e n e / Q t i a t e r n a r y sediment deformation found in Trzebnica Hills. Older authors prefered t e c t o n i c ( e n d o g e n i c ) g e n e s i s (FRECH 1 9 0 1 , 1 9 1 3 , OLBRICHT
The T r z e b n i c a Hills w e r e for many years t h e strato type r e g i o n for the Silesian Pleistocene stratigraphy. FRECH ( 1 9 0 1 , 1904) d e s c r i b e d two tills in superpositi o n in T r z e b n i c a outcrops: t h e Elsterian a n d t h e Saalian o n e ; b o t h were d e f o r m e d together with Neog e n e clay in substratum. Later, TIETZE ( 1 9 1 0 , 1 9 1 5 ) and FRECH ( 1 9 1 3 ) found that t w o Pleistocene tills o c c u r also s o u t h w a r d s the T r z e b n i c a Hills, n e a r W r o c l a w . DNTRICIT ( 1 9 1 4 ) a n d t h e n MEISTER ( 1 9 3 5 ) a n d SCHWARZBACH ( 1 9 4 2 ) d e s c r i b e d t h e next till near T r z e b n i c a , which overlay discordantly d e f o r m e d , older tills a n d N e o g e n e clay. This till, w h i c h w a s s u p p o s e d t o represent t h e Wartanian (SCHWARZBACH 1 9 4 2 ) , w a s found only in few sections: G l u c h o w C o r n y , T a c z o w Wielki, Radlow, Raszyn, T r z e b n i c k i Las
geological cross-sections see Fq 3
m sires investigated in detail
B u k o w y a n d D r o s z o w (DITTRICH 1 9 1 4 , M E I S T E R
1935, SCHWARZBACH 1 9 4 2 ) . In all cases, it w a s only 2-4 m thick, usually c o v e r e d b y loess a n d its lateral extent w a s unknown, p r e s u m a b l y small.
1 9 2 4 , CZAJKA 1 9 3 1 , MEISTER
1935).
How
ever, s i n c e the work o f B E R G E R ( 1 9 3 7 ) , t h e g l a c i o t e c tonic g e n e s i s (push m o r a i n e ) have b e e n usually pre fered a n d the age o f deformation was related t o t h e Wartanian 1954,
stage
1955,
(SCHWARZBACH
KRYGOWSKI
PACIIUCKI 1 9 5 2 , ROZYCKI
1950,
1942,
WOLDSTEDT
WALCZAK
1951,
1 9 5 7 , 1 9 6 8 , ROTNICKI I 9 6 0 ,
1 9 6 7 ) , although G O L A B ( 1 9 5 1 ) and LYCZEWSKI ( 1 9 6 4 ) still a d v o c a t e d a r g u e m e n t s o n their t e c t o n i c g e n e s i s .
2.2 R e s u l t s o f r e c e n t g e o l o g i c a l i n v e s t i g a t i o n s R e c e n t geological investigations indicate that t h e Silesian Lowland ( W r o c l a w region) can b e subdivid ed into t w o regions: the Wroclaw Basin with 4 0 - 8 0 m thick P l e i s t o c e n e s e q u e n c e , which is s u r r o u n d e d by a r e a s with thin ( b e l o w 2 0 m ) or n o P l e i s t o c e n e deposits and with N e o g e n e clays at t h e g r o u n d sur face (CZERWONKA & KRZYSZKOWSKI 1 9 9 2 ) . T h r e e Pleis-