Contr. Tert. Quatern. Geol. 36(1-4) 59-72 15 figs, 1 tab Leiden, December 1999

The Campine clays and sands in northern Belgium:

a depositional model

relates to sea level fluctuations

Frieda Bogemans

Vrije Universiteit

Brussels, Belgium

Bogemans, Frieda. The Campine Clays and Sands in northern Belgium: a depositionalmodel related to sea level fluctuations.— Contr. Tert

Quatem. Geol., 36(1-4): 59-72,15 figs, 1 tab. Leiden, December 1999.

contributions in the northern area the discusses the conditions The first in a series of on Quaternary deposits Campine (Belgium), present paper

of and well and the these deposition processes involved, as as a reconstruction of sedimentary palaeoenvironments stratigraphic position of strata

within the the of these these consist of Quaternary sequence. Only sedimentary characteristics of the lowermostportion deposits are outlined;

sandy-clayey sediments, reaching a thickness of more than 40 metres. Five sedimentological units are recognised; each unit accumulatedeither

in an estuarine or in a fluvial-aeolianenvironment.The succession ofpalaeoenvironments occurs in an alternating pattern, with fluvial-aeolian

The between these the result of level fluctuations within that deposits following upon estuarine strata. transitions are primarily sea particular

stratigraphic interval. In contrast, the continuous evolution within estuarine deposits is tectonically induced.

Key words — Lower quaternary estuarine environment, fluvial and aeolian deposits, sea level fluctuations.

Dr F. Bogemans, Vrije Universiteit Brussel, Department ofGeography, Pleinlaan 2, B-1050 Brussels, Belgium.

Contents interpretation of these deposits; he first of all pointed out

addition that they displayed a complex composition. In to

clay also sand, gravel and an alternation of sandy and Introduction p. 59

60 clayey sediments were observed. Delvaux interpreted these Study area p.

as of a vast delta, in which constant physical changes Description of sedimentological units p. 60 part either marine fluvial conditions Reconstruction of environments 65 occurred; or predominated. depositional .... p.

Rutot (1897) elaborated on Delvaux's data, and as- Discussion and conclusions p. 67

69 signed these deposits to a fluvio-lagoonal environment, Acknowledgements p. formed in the Meuse delta. References p. 70

Lorie's (1907) work is a milestone in geological studies

of the Campine area. On the basis of field work data col-

Introduction lected in 46 clay pits, he introduced four lithological units,

discussed their mutual relationship and reconstructed the

palaeosedimentary setting. With the exception of the The lowermost portion of the Quaternary sequence in the

unit, which was considered to be marine in northern Campine area, known as the Campine Clays and uppermost Lorie favoured estuarine environ- Sands (Tavernier, 1942, 1954; Paepe & Vanhoorne, 1970, origin, an depositional

1976), has been a matter of dispute for over a century. ment. in the of the These strata consist of sandy and clayey sediments, and A change interpretation Campine area with Tavernier's reach a thickness of more than 40 metres in most areas deposits came (1942, 1954) papers: no

were these considered to be estuarine or marine, but (Bogemans, 1994, 1997, 1998). The controversy concerns longer fluvial. How he arrived this conclusion is both the genesis and stratigraphic position of these depos- at not explained

its. In the is made to reconstruct in the cited present paper, an attempt papers. their origin and the evolution of the sedimentary environ- Dricot (1961) rejected this interpretation. The large ment within the interval represented. The stratigraphic concentration of Chenopodiaceae, in combination with position ofthese strata within the Quaternary sequence will phanerogamic halophytes, that occur in the clay facies discussed in full in suggests the of a coast, more of a salt a forthcoming paper. vicinity precisely marsh. characteristics biotur- Delvaux (1891) was one of the first to present an Besides, granulometric and 60

bation traces in the underlying micaceous stratified fine Brabant) bordering in the north. In the southern Nether- sand pointed to a tidal flat depositional environment. lands and northern Belgium the Campine Clays and Sands

Paepe & Vanhoorne(1970) bundled a series of obser- predominate in the Quaternary sequence. vations made in several clay pits, down to depths of 10 With the exception of the most southeasterly part of the metres. Two clay units were introduced, separated by a study area, the Cenozoic substratum is the Lillo Formation sand unit. In the uppermost clay unit at least three phases (de Meuter & Laga, 1976), which consists of grey and

found be These sands. The lower is and of deposition were to distinguishable. are greyish brown shelly part clayey separated by phases of gully incisions, infill and peat contains several shell layers. In the upperpart, clay content formation. The whole series is situated in a tidal flat envi- gradually decreases as does the shell content. In the ronment. The underlying sand unit is offluvial and aeolian southeasterly part of the area either the Poederlee or Mol

and is origin typified by peat horizons and periglacial formations form the upper part of the Cenozoic sequence.

The lowermost unit has Formation is sand phenomena. clay sedimentary The Poederlee a fine, slightly glauconitic features identical to those of the uppermost unit; here only with small lenses of clay in the lower part, and a base of two clay members were observed. gravel of rounded quartz, flint and silicified carbonates. The

Geys (1975, 1978) again introduced the fluvial origin upper part is occasionally strongly oxidised and contains interpretation, on the basis of granulometric analyses limoniticsandstones with shell moulds. The Mol Formation

with His together microscopy of quartz grain morphology. contains pure white medium-fine to coarse sands, with conclusions, however, lack accuracy. lignitic horizons and lenses of micaceous clay; these are the

The work is that of Kasse famous sands used in the most recent (1988, 1990), quartz glass industry. who followed the tripartite subdivision introduced by In between the above-mentionedCenozoic substratum

Paepe & Vanhoorne (1970, 1976), as well as their genetic and the Campine Clays and Sands is the Merksplas Forma- interpretation, although he went into more detail here. On tion (de Meuter & Laga, 1976; Bogemans, 1994, 1997,

basis of concluded of medium- the of a study heavy minerals, Kasse 1998), consisting grey, to coarse sands, spo- that both the and lower units had an unstable radically medium fine (180-250 fim), occasionally con- upper 'clay' heavy mineral association, supplied by the River Rhine. A taining gravel, shells and shell fragments. Silty to clayey stable heavy mineral association, derived from central lenses or layers, whether or not organic, as well as wood

interca- scattered facies Belgium by rivers such as the Scheldt typifies the fragments are all over (Bogemans, 1994). lated unit. His observations involved section of The of the is situated in a to depths most easterly part study area more or less 30 metres, so that still portions of the Campine the borderregion ofthe Roer Valley Graben, which started

Clays and Sands were not reached and remained uninter- to develop during the Cenozoic in response to the Alpine preted. stress regime (Ziegler, 1978). Tectonic units which have a

the the direct impact on the geological history of area are

Eastern and Western Campine Blocks, which are regions of

STUDY AREA intermediatesubsidence to the west and southwest of the

graben (Geluk et al., 1994). As a consequence, sedimentary

thickness in the study area remained rather limited in

comparison to the active graben itself.

DESCRIPTION SEDIMENTOLOGICAL UNITS

Unit A - a sandy complex

Unit A is the lowermost memberof the Campine Clays and

and is the Sands, present all over study area, reaching a

of This size thickness 30 metres. sandy complex has a grain

distribution from fine to medium fine ranging very sand,

medium sand being less common. In some restricted places,

mud deposits dominate. Besides typical minerals such as

micas and glauconite, also vegetation remains, peaty dots,

peat lumps and wood fragments are part of the general

composition of Unit A. Within this unit two distinct facies

Location of the Fig. 1. study area. are recognised:

— Fades I: consists of fine to medium fine in very sand, which less than 63 distinct. These The study area is situated in northern Belgium, in the particles jum are are province ofAntwerp (Fig. 1), being known as the northern deposited as layers or are part of a stratum, the latter

Campine area, with the Netherlands (province of Noord- forming wavy bedding or flasers (Fig. 2). 61

Fig. 3. Sedimentological description of Facies II of Unit A; for

legend see appendix.

— be thick with sand Fades II: may very (Fig. 3), gener-

ally fine to medium fine. Medium sand, if present, is in a

basal position, occasionally resulting in fining-up se-

quences. The wavy bedding as well as flasers are strongly

reduced. The horizontal stratification and planar cross

bedding are. occasionally vague and containwater escape

structures. Very typical in this facies is the presence of

several reactivation surfaces. Where this facies is found at Fig. 2. Sedimentological description of Facies I of Unit A; for

the of Unit soil horizon is sometimes legend see appendix. top A, a developed.

Unit B - of successions Other typical structures are horizontal stratification, mas- a complex fining-up sive bedding, and low-angle and planar cross stratification.

of Unit this unit is restricted the The orientation of planar cross stratification changes over Resting on top A, to limited depths. Scour structures, microfaults and deforma- southerly portion of the study area and may reach a thick-

of9 metres there. It consists of successions tion structures also are very common. Less frequent are ness fining-up

which from 2 to than with the bioturbation traces, small-scale ripple bedding and organic the numberof ranges more 7,

vertical extension of succession 1 horizons. As noted above, in some restricted places of the mean a being metre.

from the the of the study area this facies is predominantly a clay facies, mas- Apart topmost part greatest portion

In the succession is of fine to medium-finesand, with sive or with lenticular or wavy bedding. wavy- composed

Bioturbation traces are sand being rather exceptional. There is a bedded parts load casts may occur. homogeneous rather uncommon. continuous transition from one sand fraction to another. A 62

of is further induced amount smaller than 63/rm is distinct in this unit. Sediments are poor degree sorting by large

silt and Glauconite is less common. of clay particles. very common, micaceous, glauconite being

although the concentration limited; in contrast, micas are

virtually absent. Different types of cross bedding together — Fades I: is restricted to the funnel-shaped depression;

with convolutions are the typical sedimentary structures the infilling material is predominantly silty and, contrary to

(Fig- 4). expectation, calcareous. Within the depression both grain

size distribution and sedimentary structures change de-

location. the massive and pending on In southerly part,

lenticularly stratified mud deposits are observed, together

with some obliquely to subhorizontally laminated, wavy

mud layers with clear lower bounding surfaces. At some

levels, heterogeneous sand deposits intercalate.The typical

sedimentary structures in these sands are horizontal stratifi-

cation, massive bedding and planar cross stratification.

Fig. 4. Typical sedimentation pattern of deposits of Unit B.

The convoluted bedding is frequently related to loamy layers. In the basal portion bioturbation traces occasionally

occur. The uppermost layer ofa succession consists of fine clastic from fine sand In material, ranging very to clay. Fig. 5. Paler and darker zones in the mud deposits of Facies I of both and clayey sandy top layers, peat, vegetation remains Unit C, with microfaults.

and relicts of pedogenic processes may occur (Fig. 4). A

sandy top is either homogeneous or contains finer-grained clastic layers. In the contact zone between the uppermost Very typical for the southerly and central portions of the

layer and the underlying sediments deformationstructures depression are paler and darker zones (Fig. 5) within the

may occur. mud deposits, just as the alternating complexes of greyish

medium-finesand and stratified brown, layers grey, clayey

silt layers in which vertically oriented vegetation remains

Unit C - a clayey/sandy complex and dessication cracks occur (Fig. 6). In the mud deposits,

microfaults are quite common (Fig. 5). As in the northerly

If Unit B is present, Unit C lies directly on top of that, part of the depression, sand input increases in the mud

otherwise it rests on Unit A. Although in a restricted region deposits, wavy and lenticularbedding becoming the domi-

of the study area, a funnel-shaped depression in the vicinity nant stratification. Within the ripples foresets are pre-

of Ballematen, the thickness of Unit C attains 20 metres, served, and show bidirectional orientations. The sand

the thickness from 5 10 In in this of the show identical commoner ranging to metres. layers present part depression

general, two sedimentationcycles are observed in this unit, sedimentary structures. Locally, large concentrations of

except for the funnel-shaped depression, where three cycles loadcast structures exist. Less frequent, but more vertically

succeed each other. Apart from the northerly, the most extended, are chaotic deformations composed of sand and

and fraction Bioturbation all. southerly easterly portions of the area, the mud. traces are not common at 63

withinthe study area determines the sandy or clayey nature

ofthe complex. In the central part, clayey sediments prevail

(Fig. 7), while in other areas sandy sedimentpredominate.

In a clayey complex, deposits consist of mainly grey to

bluish grey clay, silty or not. The prevailing structures are

massive bedding, lenticular and wavy bedding with some

deformation structures (Fig. 8). Small sets of alternating

clay and sand layers, with a dominance of sand layers, also

are common. In a predominantly sandy complex the texture

of the sand ranges between very fine and medium fine. In

restricted places, however, a coarser sand fraction is ob-

served, mostly in the basal position of the facies. The

stratification is massive, subhorizontal to planar, the latter

with changing orientations, either curved or not.

Unit D - a sand complex with several soil horizons

This unit has restricted distribution, limited to a very being the vicinity of Merksplas, Rijkevorsel, Malle, Beerse and

Oud-Turnhout(Fig. 9). Although the thickness is between

1.5 and 3 the is rather intricate. Fig. 6. Vertically oriented vegetation remains and dessication m., depositional sequence Two lithofacies in the order. cracks within Facies I of Unit C. are distinguished, always same

One ofthe two, however, may be absent:

— Fades II: is distributed in the and is generally area,

composed of a clayey-sandy, non-calcareous micaceous — Fades I (lowermost fades): consists of fining-up suc- complex. Vegetation remains and wood fragments are quite cessions, with the formation of a succession invariably

but in rather small Localisation common, occur amounts. preceded by an erosional phase.

Fig. 7. Sedimentological description of a predominantly clayey complex of Unit C; for legend see appendix 64

The coarsest fraction consists of medium-fine sand and

constitutes with fine sand the greatest part of a succession.

The stratification varies from continuous, even horizontal

to continous and discontinuous slightly oblique to wavy

bedded. A lotof deformationstructures, such as dewater-

ing structures, slumping and convolutions, appear. Also

typical are vegetation remains, which may either have

accumulated simultaneously with the deposition of clastic

sediments The or be preserved in growing position. top

facies of a succession comprises clayey silt, silt or black

sand, the last-named compacted. Peaty material, either

deformed or not, is quite common (Fig. 10). Ripple bed-

ding and convolutions are the dominant sedimentary

structures; highly interesting also is the presence of frost

cracks and wedges.

— Fades II (uppermost fades): is preceded by a limited

of erosional phase; the lowermost bed is made up sand,

slightly silty at the base with diffuse horizontal to massive

On of this follows bedding (C) (Fig. 11). top a podsol,

which is also cryoturbated (D). In these deposits frost

cracks which are formed in the superimposed layers are

present. On top of the podsol is a unit composed of loam

at the base followed by an alternating complex of sand and

loam The whole unit is stratified.These layers (E). wavy

sediments were post-depositionally modified by secondary

displacements and deformations. Large epigenetic frost Fig. 8. A detail of the prevailing structures within a clayey

cracks are observed in these complex of Unit C. deposits.

9. Illustration of the limited distribution of D Turnhout scale 1:50 Fig. Unit (topographic map no. 8, 000). 65

Deformation structures with a predominance ofload casts Fig. 10. Close-up of deformation structures within the peaty material in the wavy-bedded deposits and intricate deformation of Unit D. structures in the massive and lenticular-beddedfacies are

also noted. The sandy deposits, if present, have a grain size

distribution ranging from very fine to medium fine. The The following unit (F) is composed of a subhorizontally massive, horizontaleven and stratifi- stratified fine the base, followed oblique, slightly wavy grey, sand layer at by laminations cation prevail, whereas foresets and ripple are brown compacted slighty silty sand which corresponds with intercalations in these much less common. The clayey the B horizon of a podsol. Within this unit, pale sand either discontinuous and sandy deposits are present as intercalationsboth horizontal and vertically oriented, occur continuous oblique to subhorizontal layers or as pebbles of which a decrease in concentration towards the base is

and lenses. Deformation structures through water recorded. The frost cracks, which are formed superimposed

as bioturbation traces, microfaults and the older confined to the sediments below the expulsion, just on ones, are

horizons are observed in the sand deposits. B horizon. organic

RECONSTRUCTIONOF DEPOSITIONAL Unit E - a clayey/sandy complex

ENVIRONMENTS

Unit E is the uppermost unit of the Campine Clays and

Sands. If Unit D is present, Unit E lies directly on this, or, Sedimentological characteristics of Unit A suggest a tidally

rests on Unit C. Its distributionarea is more limited to the dominated estuarine environment. The first depositional

south in that of Unit C. the of formed sand comparison to Generally, facies (facies I) is composed strata on flats,

thickness of these deposits increases in a northerly mudflats (higher and lower mudflats, see Evans, 1965), or

and direction. Four to five metres in the south, to 10 metres in gullies, the latter with or without bar deposits and, to a

in the central of its distribution Unit E marsh more, as part area. lesser degree, consists of salt deposits. However, one

is micaceous non-calcareous subenvironments dominatethe predominantly a fine-grained, of the tidal may sequence.

complex in which the silt fraction is strongly limited. The Facies II is composed mainly of sediments which accumu-

clay deposits are massive, subhorizontal and lenticularly lated as intertidal sand bodies and sand flats. Within Unit

lenticular and stratified, more limited is wavy bedding. The A, two types of sequences are observed: one composed

of fine sand another dominated wavy bedding are composed clay, and/or mainly of fining-up cycles, and by a

silt. In the also continuous and the latter coarse clay deposits appear coarsening-up cycle. In case, a fining-up succes-

discontinuous sand with internal stratification in the basal The layers, sion may be present in a position. coarsening-up

thicker layers (Fig. 12). Typical within the clay deposits are cycle is restricted to an easterly depression (located on

horizons. one or several organic horizons or soil Moreover, sheet Turnhout, map scale 1:50000) and is composed of

small vegetation remains are scattered all over the clay mudflat deposits and occasionally salt marsh deposits at the

facies. Bioturbation traces are quite common, but with base, followed by channel deposits and sand bar deposits

varying density (Fig. 13). at the top. 66

Fig. 12. Across-section through a clayey complex ofUnit E.

Fig. 13. Typical bioturbation found in Unit E. 67

The fining-up cycles consist mainly of sand flat and Unit E, the alternating complex, accumulated in a rather

formed intertidal sand body deposits in a basal position and wet environment where adhesion structures (Glen-

superimposed by finer-grained deposits in a prograda- nie, 1970; Hunter, 1973, 1980; Kocurek & Fielder, 1982).

fluvial and tional order. Salt marsh deposits are rather exceptional. Periglacial phenomena are present in both the

The sedimentary structures described for Unit B are aeolian deposits. Besides the typical cryoturbations (Fig.

typical of a fluvial environment in which downstream 10) and frost cracks also imprints of segregation ice (van

accretion elements(Miall, 1996) prevail. Since this depo- Vliet-Lanoe, 1985) occur in the aeolian sediments(Unit F,

and sitional unit consists of a succession of bars, the lateral in Fig. 11). All palaeosols, organic horizons podsols

migration of the fluvial system in question was probably are soils with a short durationof formation(Meyer, 1987;

limited whereas downstream migration of the bars pre- Retallack, 1990), during periods ofstagnation in between

dominated. The convolutions present in the sand deposits depositional phases.

most probably formed due to partial liquefaction of water- Unit E has the sedimentary features of a tidally domi-

distribution saturated sediments as the result of migration of large natedestuary. In the greatest part of the area

the sedimentation dominated salt bedforms over unconsolidated sandy sediments during cycles are by mudflat,

rather than the and Sand flat less high-flow stages (Plint, 1983), represent marsh floodplain deposits. deposits are result of a combinationof disintegration oforganic matter important. In the northerly part, however, a fining-up and presence of loamy material (Barwis, 1978). The sequence of sand flat, mudflat and salt marsh and/or

situated deformation structures observed at the contact zone floodplain deposits occurs. All these deposits are between the the estuarine and uppermost bed and the underlying sediments in the intermediate zone between purely

are ascribed to fast uprising bars, with water expulsion the tidally-influenced fluvial zones. Pollen analyses

taking place (Singh, 1977); dewatering pipes may form. (Alam, 1989) and clay fabric studies (Sethi, 1989; Wartel

These data together with the limited extension of the et al., 1997) confirm that within the depositional environ-

successions brackish conditions point to a braided character of the fluvial ment alternating freshwater and water

braidedriver system, to a perennial sandy system. Because prevailed.

most top facies are preserved, accumulation most proba-

bly was the dominant process in this environment.

On the basis of sedimentary structures the two facies DISCUSSION AND CONCLUSIONS of Unit C are interpreted as having been deposited in a

tidally dominatedestuary. The spatial variation of facies The above description of the Campine Clays and Sands

1 of this unit is the result of the transition of depositional shows the constant repetition of the sedimentationpattern,

subenvironments within the estuary. In the southerly part 'estuarine-fluvial and/or aeolian'. This repetition is the ofthe funnel-shaped depression floodplains, channels and consequence of sea level fluctuations, which will be natural levees dominatethe environment. These features explained below (Fig. 14). In addition, within the deposi- influenced channel belong to a tidally (sensu Dalrymple et tional model a constant evolution to a final phase of a

al., or to the of an 1990) upstream part estuary according purely terrestrial environment may be noted.

to Woodroff al. the et (1989). Going northwards, deposi- The componentsof Unit A, the fining-up as well as the tional features evolve from bars and into point floodplains coarsening-up cycles (the latter observed in a single

tidal flats. The latter of the flow are typical upper regime depression) accumulated during one oscillatory motion of

sand flats As of (Dalrymple et al., 1990). a consequence sea level. Indeed, the fining-up cycles most probably

low sand mudflats the sand flats. The input, replace high formed when the sea level rise was already diminishedand percentage of silt in the south points to a river supply sediment input became the modifying factor in the forma-

which is indeed confirmed the (Wartel, pers. comm.), by tion of the depositional sequence. This phenomenon has reconstructed palaeoenvironment. already been observed in many estuaries and been mod- In the facies clay-dominated II of this unit, sediments are elled by Knight & Dalrymple (1975), Woodroffe et al. mudflat sometimes deposited on a and/or floodplain, (1989), Dalrymple et al. (1992), Allen (1990), Nicols et

sand flats. The areas be al. and Woodroffe al. When adjoined by depositional may (1991) et (1993). an estuary

dissected by gullies. In the sand-dominatedfacies, sand has reached its inland position, the finalinfilling starts and

flat deposits are the most important. results in the sequence described above (Nicols & Biggs,

The sedimentary characteristics of Unit D to a The point 1985; Dalrymple, 1992). presence of several fining- terrestrial origin of this facies. The lowermost facies is within Unit is attributed the lateral up cycles A to migra- fluvial, of bar, bench and tion of the and variations in consisting floodplain deposits. system not to sea level or

the Very typical are peaty floodplain deposits together sediment input. In between the cycles no deposits are with flashflood sheetflood crevasse splay deposits, or found that point to a rearrangement of the depositional deposits. The sedimentary characteristics of the uppermost environments; moreover, no large-scale erosion took facies are related to an aeolian environment in which The formed when place. coarsening-up cycle sea level several subenvironments are recognised. Units C and D in dropped again. Consequently, erosion occurred, followed

11 are of under conditions. Fig. typical deposition dry by channel infilling. Similar phenomena were described 68

by Ricketts (1994) from the Late Palaeocene Cape Pills- similarity exists concerning thickness. Thickness of Unit

bury Member of Ellesmere Island (Canada). B decreases to the north whereas that of Unit A increases.

The continued of the distribution process in a later phase outside the Besides, near the northern margin area

depression and resulted in the deposition of purely fluvial of Unit B the topmost bed of the uppermost succession is

sedimentsof braided origin. This evolution fits in a con- missing. Both elements, together with the absence ofUnit

the result tinuous process through which no large-scale erosion B in the northern part of the study area, are of

occurred in between the accumulation of units A and B. sideway cutting (Howard et al., 1968) of streams when

this level. This hypothesis is corroboratedby the presence ofimpor- they reach theirbase level, in case sea During

tant bioturbation traces in the basal strata of Unit B. Unit this particular period, the coastline was nearby (Zagwijn,

B dips in a northerly direction just as does Unit A. No 1979,1989).

Fig. 14. Illustration ofthe relationship between sea level fluctuations and patterns of sedimentation.

This erosional process continued in a restricted area near nantly composed of mudflat and sand flat deposits in the

Ballematen and resulted in the formation of the funnel- northand mud flat and/or floodplain deposits together with

shaped depression. Unit C is unique in the sense that in the channel and point bar deposits in the south. Sand flat

less funnel-shaped depression a complete sea level rising stage deposits are common. is preserved. The infilling of this depression took place On the basis of the depositional features of both units A

level succession ofmudflat and C it that the coastline situated north- during rapid sea rise, forming a seems was more

deposits in the north and meandering to estuarine deposits westerly during the formation of Unit C than during the

in the central and southern part. In the next stage, when the accumulation of Unit A. This finding corresponds to the

invaded reconstruction basin estuary more inland, the whole area was flooded palaeogeographic of the North Sea as

which (Fig. 15) produced some fining-up cycles predomi- presented by Zagwijn (1989). 69

The succession of units C and D is quite similar to thatof

units A and B. First of all, erosional activity in between

level both units was also negligible. The lowering of sea

that fluvial made it also during that period possible a purely

depositional environment was established. Different,

however, is the presence of aeolian deposits. The evolution

of sedimentary characteristics within the aeolian deposits

points to an evolution into drier circumstances. Very

limited and striking is the moreover fragmentary preserva-

tion ofunit D. This situation is most probably the result of

combined action of downcutting and sideway cutting of

active streams (Howard et al., 1968). The southern part,

level where Unit D is preserved, was located above base

and was consequently incised whereas the northern part,

situated around base level, was subject to sideway cutting,

resulting in the total disappearance of the unit.

Unit of the The depositional features of E are typical

the reaches its final phase of a transgression when estuary

furthest position inland. In the first phase, those areas were

invaded where Unit D was eroded and sand flat deposits

covered accumulated. In the final stage, the entire area was

by the estuary and mud flat, floodplain and/or salt marsh

deposits formed in the southern part, while in the northalso

sand flats were deposited.

The presence of the above-mentioned depositional

features indicate that during the deposition of Unit E the

coastline distance from the than was at a larger study area

during accumulation of units A and C. This finding is in

agreement with Zagwijn's (1974, 1979, 1989) hypothesis

concerning the continuous migration of the coastline in a

northwesterly direction during the Late Tiglian.

Sands The formationof the Campine Clays and as a

succession of estuarine and purely terrestrial deposits is

primarily the result of sea level fluctuations induced by

climatic oscillations. However, the evolution within the

estuarine deposits is tectonically determined. Tectonic

activity is indeed the reason why no more estuarine depos-

its accumulated during the remainder of the Quaternary in

this particular area. Mainly in the southern part of the North

Sea there was a gradual narrowing since Late Miocene until

the sea completely retreated in the early Middle Pleisto-

cene. According to Zagwijn & Doppert (1978) this situa-

tion is the result of epeirogenic uplift or tilting of the

hinterland and the of central European changing pattern

subsiding areas in the basin.

ACKNOWLEDGEMENTS

I am greatly indebted to Professor R. Paepe (Vrije Univer-

siteit Brussel), who made this work possible, to the Belgian

Geological Survey (Brussels) for putting geological data at

my disposal, and to Professor P. de Boer (Universiteit

for Utrecht) comments on an earlier typescript. During the

the from the start, present study was supported by a grant

Fig. 15. Geological constitution ofthe Campine clays and sands in National Science Foundation, which is gratefully acknowl-

the vicinity of Ballematen. edged. 70

REFERENCES Kasse, K., 1988. Early-Pleistocene tidal and fluviatile environ-

ments in the southern Netherlands and northern Belgium.

190 Amsterdam (Vrije Universiteit Amsterdam), pp. (unpubl. Alam, S.H., 1989. Palynological studies of the Lower Pleistocene PhD thesis). deposits in the Campine area, northern Belgium. Brussels (fi- the Kasse, K., 1990. Lithostratigraphy and provenance of Early- nal - 66 report Vrije Universiteit Brussel), pp. Pleistocene deposits in the southern Netherlands and northern Allen, J.R.L., 1990. The Severn Estuary in southwest Britain: its

Belgium. — Geol. Mijnbouw, 69: 327-340. retreat under marine transgression, and fine-sediment regime. Knight, R.J. & R.W. Dalrymple, 1975. Intertidal sediments from — Sedim. Geol., 66: 13-28. the south shore ofCobequid Bay, Bay of Fundy, Nova Scotia, Barwis, J.H., 1978. Sedimentology of some South Carolina tidal- Canada. In: R.N. Ginsburg (ed.). Tidal deposits. New York creek point bars, and a comparison with their fluvial counter- (Springer): 47-55. parts. In: A.D. Miall (ed.). Fluvial sedimentology. Calgary

Kocurek, G. & G. Fielder, 1982. Adhesion structures. — J. (Canad. Soc. Petrol. Geol.): 129-160. sedim. Petrol., 52: 1229-1241. Bogemans, F., 1994. Toelichting bij de Quartairgeologische Lorie, J., 1907. La stratigraphie des argiles de la Campine beige kaarten van Vlaanderen: Turnhout-Meerle. Brussels (Min.

et du Limbourg neerlandais. — Bull. Soc. beige Geol., Vlaamse 102 Gemeensch.), pp. Paleont., Hydrol., 21: 531-576. Bogemans, F., 1997. Toelichting bij de Quartairgeologische Meuter, F.J. de & P.G. Laga, 1976. Lithostratigraphy and kaarten van Vlaanderen: Essen-Kapellen. Brussels (Min. based benthonic foraminiferaof the Neo- 65 biostratigraphy on Vlaamse Gemeensch.), pp.

in northern — Bull. Ver. gene deposits Belgium. belg. Geol., Bogemans, F., 1998. Toelichting bij de Quartairgeologische 85(4): 133-152. kaarten van Vlaanderen: Maarle-Arendonk. Brussels (Min. R., 1987. Paleoalterites et Orleans Vlaamse 77 Meyer, paleosols. (BRGM), Gemeensch.), pp. 164 13: pp. Dalrymple, R.W., 1992. Tidal depositional systems. In: R.G. Miall, A.D., 1996. The of fluvial deposits. Berlin & N.P. James to geology Walker (eds). Facies models, response sea (Springer), 582 pp. level change. Ontario (Geol. Assoc. Canada): 195-218. Nicols, M.M. & R.B. Biggs, 1985. Estuaries. In: R.A. Davis Dalrymple, R.W., R.J. Knight, B.A. Zaitlin & G.V. Middleton, (ed.). Coastal sedimentary environments. New York 1990. Dynamics and facies model of a macrotidal sand-bar (Springer): 77-186. complex, Cobequid Bay - Salmon River Estuary (Bay of Nicols, M.M., G.H. Johnson & P.C. Peebles, 1991. Modern Fundy). — Sedimentology, 37(4): 577-612. sediments and facies model for a microtidal coastal plain es- Dalrymple, R.W., B.A. Zaitlin & R. Boyd, 1992. Estuarine facies

the James — J. sedim. 61: tuary, Estuary, Virginia. Petrol., models: conceptual basis and stratigraphic implications. —J. 883-899. sedim. Petrol., 62(6): 1130-1146. Paepe, R. & R. Vanhoorne, 1970. Stratigraphical position of Delvaux, E., 1891. Etude stratigraphique et paleontologique du periglacial phenomena in the Campine clay of Belgium, sous-sol de la Campine, d'apres des documents nouveaux

based on and d'une M. le baron O. Ert- palaeobotanicalanalysis palaeomagnetic dating. provenant forage execute par van

— Bull. belg. Ver. Geol., 79: 201-211. born, dans l'etablissement colonial de Merxplas, situe sur Paepe, R. & R. Vanhoorne, 1976.The Quaternary of Belgium in l'arete de partage des bassins de la Meuse et de I'Escaut. — its relationship to the stratigraphic legend of the geological Ann. Soc. geol. Belg., 18: 107-156. Verh. Krt map. —Toel. geol. Mijnkrt Belg., 18: 1-38. Dricot, E.M., 1961. Microstratigraphie des argiles de Campine. Plint, A.G., 1983. Sandy fluvial point-bar sediments from the — Bull. Soc. beige Geol., 70(2): 113-141. Middle Eocene of Dorset, England. In: J.D. Collinson & J. Evans, G., 1965. Intertidalflat sediments and their environments Lewin (eds). Modern and ancient fluvial systems. Oxford of deposition in the Wash. — Q. J1 geol. Soc. Lond., 121: Scient. Publ., 6: 355-368. 209-245. (Blackwell Publ.), Spec.

Retallack, G.J., 1990. Soilsof the past. Boston (Unwin Hyman), Geluk, M., E.J.T. Duin, M. Dusar, R.H.B. Rijkers, M.W. van den

519 pp. Berg & P. van Rooijen, 1994. Stratigraphy and tectonics of Ricketts, B.D., 1994. Mud-flat cycles, incised channels and the Roer Valley Graben. — Geol. Mijnbouw, 73: 129-141. relative sea-level changes on a Paleocene mud-dominated Geys, J.F., 1975. De sedimentologie en de morfogenetische

coast, Ellesmere Island, Arctic Canada. — J. sedim. Res., betekenisvan de Oudpleistoceneafzettingen in de Antwerpse B64: 211-218. Noorderkempen. Gent (Universiteit Gent), 230 pp. (unpubl.

Rutot, A., 1897. Les du Quaternaire de la Belgique. — PhD thesis). origines Bull. Soc. beige Geol., Paleont., Hydrol., 11: 1-40. Geys, J.F., 1978. The palaeoenvironment ofthe Kempenland clay Sethi, P.S., 1989. A comparative study of limnic, estuarine and deposits (Lower Quaternary, N. Belgium). — Geol. marine sediments, on the basis ofmicro-structures and on the Mijnbouw, 57(1): 33-43.

use of clay-fabric as a tool for Quaternary lithofacies inter- Glennie, K.W., 1970. Desert sedimentary environments. Amster-

Brussels - Vrije Universiteit Brussel, dam pretation. (final report (Elsevier), 222 pp. 1), 63 Howard, A.D., R.W. Fairbridge & J.H. Quinn, 1968. Terraces, pp. Singh, I.B., 1977. Bedding structures in a channel bar of the fluvial - introduction.In: R.W. Fairbridge (ed.). The encyclo-

Ganga River near Allahabad, Uttar Pradesh, India. — J. pedia of geomorphology. Stroudsburg (Dowden, Hutchinson sedim. Petrol., 47: 747-752. & Ross): 1117-1124.

Tavernier, R., 1942. L'age des argiles de la Campine. — Bull Hunter, R.E., 1973. Pseudo-crosslaminationformed by climbing Soc. beige Geo!., LI: 193-209. adhesion ripples. — J. sedim. Petrol., 43: 1125-1127. Tavernier, R., 1954. Le Quaternaire. In : P. Fourmarier (ed.). Hunter, R.E., 1980. Quasi-planar adhesion stratification. An Prodrome d'une description geologique de la Belgique. Brus- eolian structure formed in wet sands. — J. sedim. Petrol.,50: sels (Soc. geol. 555-590. 263-266. Belg.): 71

1979. and Middle Pleistocene coastlines in Vliet-Lanoe, B. van, 1985. Frost effects in soils. In: J. Boardman. Zagwijn, W.H., Early

Soils and Quaternary landscape evolution reconstruction. — the southern North Sea basin. In: E. Oele, R.T.E. Schiitten-

J. Quat. Sci., 3(1): 85-96. helm & A.J. Wiggers (eds). The Quaternary history of the

1989. North Sea. — Acta Univ. Annum Quin- Woodroffe, C.D., J. Chappell, B.G. Thom & E. Wallensky, ups. Symp. Univ.

Depositional model of a macrotidal estuary and floodplain, gent. celebr., 2: 31-42.

the South Alligator River, northern Australia. — Sedimentology, Zagwijn, W.H., 1989. The Netherlands during Tertiary and

36(5): 737-756. Quaternary: a case history of coastal lowland evolution. —

Woodroffe,C.D., M.E. Mulrennan& J. Chappell, 1993. Estua- Geol. Mijnbouw, 68: 107-120. Diemen W.H. & J.W. 1978. Cenozoic of the rine infill and coastal progradation, southern van Zagwijn, Doppert, Upper

Gulf, northern Australia. — Sedim. Geol., 83: 257-275. southern North Sea basin: palaeoclimatic and palaeo-

— 577-588. Wartel, S., P.S. Sethi & F. Bogemans, 1996. Clay fabric as an geographic evolution. Geol. Mijnbouw, 57:

tectonics and basin indicator of cyclic changes in an estuarine palaeoenvironment Ziegler, P.A., 1978. Northwestern Europe:

— — 57: - Lower northern Geol. 589-626. Pleistocene, Campine area, Belgium. development. Mijnbouw,

Bull. Inst. r. Sci. nat. Belg., Sci. Terre, 66: 193-202.

Zagwijn, W.H., 1974. The palaeogeographicevolution of the Manuscript received 8 October 1997, revised version accepted 27 Netherlands during the Quaternary. — Geol. Mijnbouw,53: March 1999. 369-385. 72

LEGEND

Lithology Texture

clay clay =* S : silt

silt I ss : sand

j| sand

I silty p= 1 — clay

b clayey |jjj silt

jxj soil horizon m Rx? ■ - - fraction 0-62p,m

O J clay lenses O •:•!•! very fine sand

peat dots ££ |v v •v.;v fine sand

peat lumps • • I". medium sand

peat or peaty material • ■ ■ coarse sand

sand Structures {■J very coarse Sedimentary [jCj

<• ripple lamination

- trough cross-bedding

planar cross-bedding

| massive bedding

J wavy bedding

Table 1. Legendtologs.