Figure 2. Geologioal structure of basement. 
A - orystalline basement: a -oontours of a top surfaoe 
/in meters, after Kubioki,Ryka 1982/, b -faults, o - 
llthologioal boundaries. Lithology /after Karaczun, 
Kubicki,Ryka 1982/: 1 -granitoids, 2 -unsubdivided 
gneisses, 3 -unsubdivided gneisses and eunphlbolites, 
4 -pyroxene gneisses and eunphlbolites, 5 -unsubdivi- 
ded migmatites, 6 -pyroxene migmatites, 7 -anateotio 
and palingenetio granitoids, 8 - rapakivi like grani 
toids. 
B - Zeohstein-Mesozoio series /after Dadlez 1980/; 
a -oontours of basal surfaoe of series /in m/, b -oon 
tours of the base of Upper Cretaceous, o -faults pene 
trating lower part of the series /mainly Zeohsteln or 
Zeohstein and Triassic/, d -faults outting the whole 
series. Both structural surfaces inclined southwards. 
3 GEOLOGICAL SETTING 
In the Vistula Delta Plain area the orystalline base 
ment of the peri-Baltio syneollze lies at depth of 
about 3500m /in the east/ and more than 4000m /in the 
west of the area/ - Karaczun,Kubioki,Ryka 1982. 
The faulting character and wide-radius downwarps and 
uplifts of the top surface of the basement seem to in 
fluence the development of the later sedimentary oover 
of the platform. The top surfaoe of Lower Palaeozolo 
oover ooours at the depth of about 1500m /in the 
northern part/ to about 2000m /in the southern part 
of the area/ - Fig.2A. 
The Zeohstein-Mesozoio series represents the follo 
wing part of the geologioal seotion, the lower part of 
whioh displays some big faults /Dadlez 1980/ - Fig.2B. 
The upper part of the series is built up of oaloareous 
and oaloareous- silloeous deposits of Upper Cretaceous 
/Turonian to Maestrichtian in age/. These brittle se 
diments underlie, in turn, the loose and soft Caino- 
zoio sedimentary oover the thickness of whioh varies 
from 50m /in Gdansk vicinity/ up to 200m /east- and 
southwards from Gdansk - in Tozew and Malbork region/. 
Top surfaoe of the Upper Cretaceous series occurs 
at the depth of approximately 90m dipping gradually 
eastwards and westwards reaohing the morainio plate 
aux. It displays a dlstlnot relief due to an intensi 
ve erosion, possibly facilitated by the faults -Fig.3. 
The looal small faults are indentlfied in the numerous 
geoteohnioal works basing, however, only on analysis 
of denivelations of Cretaoeous strata observed in 
boreholes /dojskl 1976/, 
In the area of Zulawy Wiálane /Vistula Delta Plain/ 
the Tertiary series overlies the Upper Cretaoeous se 
diments. This series has been looally strongly eroded 
too, due to the erosion and exaration whioh aoted at 
Tertiary/Quaternary boundary as well as in Pleistoce 
ne, affooting - in the distlnot area - even the young 
est Upper Cretaoeous strata /Fig.4/. 
The sediments of three glaoiation and the deltaio 
Holooene ones build the Quaternary oover. Pleistooene 
series seems to have very oomplioated inner struoture 
what results from a combined influenoe of the diffe 
rent prooesses varlated in time and spaoe, as: 
different kinds of accumulation /glaoial, marginal, 
marine, fluvial/, erosion and exaration, glaciteoto- 
nlos and possibly - tectonics. The thiokness of the 
Pleistooene sediments equals in the 2ulawy area 
approx. 70m. Their top inclines slightly northwards. 
In fculawy area the relief of sub-Holocene series is in 
details insufficiently recognized. Pleistooene sedi 
ments surfaoe is eroded and buried with Holooene depo 
sits of thiokness from 0 to 20m /increasing north- and 
eastwards/. These deposits compose the deltaio plain 
at the altitudes from about lm b.s.l. to lm a.s.l. 
Figure 3. Top surface of Cretaoeous series; 1 -bounda 
ry of morainio plateaux, 2 -oontours of top surfaoe of 
Cretaoeous series /in m b.s.l./, 3 -boreholes and 
cross-seotion lines. 
Figure 4. 
of morain 
ce /in m 
b -Tertia 
The pre 
the Holoc 
/Mojski i 
peats and 
Its dev 
two stage 
Tertiary, 
ting the 1 
ones a wi 
has survi 
the devel 
tion/ of 
The depre: 
ne - desp 
that last 
eroded an 
glaoiatioi 
glaoiisos 
level of i 
oession o 
of the er 
uplift of 
period/, - 
- due to i 
The las 
vial acoui 
of sedimei 
ness of tl 
were acoui 
goon form 
from the i 
sediments 
It resu 
sion on ol 
ned such 1 
Cretaoeoui 
nature of 
-Quaternai 
the Quatei 
4 ANALYSIS 
The foil« 
of top sui 
of lower i 
as well a: 
occurence