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INH LTSVERZICHNIS

TEIL 1

Aufsätze

Elaine TurnerAriendorf — Quaternary deposits and palaeolithic excavations in the Karl Schneider gravel pitwith contributions from Wolfgang Boenigk, Manfred Frechen,Matthijs van Kolfschoten, Elisabeth Schnepp, Ernst Sefkov and Karel Steensma(Tafel 1-8) 3

Markus Egg . Borut Kri~Ein neuer hallstattzeitlicher Schildbeschlag aus Novo mesto, Siowenienmit einem Beitrag von Anke Estor(Tafel 9-16) 193

Martin LuikDie römischen Militäranlagen der Iberischen Halbinsel von der Zeit der Republikbis zum Ausgang des Prinzipats — Ein Forschungsüberblick(Farbtafell-Il) 213

Yasmine FreigangDie Grabmäler der gallo-römischen Kultur im Moselland —

Studien zur Selbstdarstellung einer Gesellschaft(Tafel 17-46) 277

Tafeln 1-46

TEIL 2

Aufsätze

Susanna KünzlAntonia Minor — Porträts und Porträttypen(Tafel 47-62) 441

Nicolae GudeaDer dakische Limes — Materialien zu seiner Geschichte (~~1_*113) 497

Jahresbericht

des Römisch-Germanischen Zentralmuseums,Forschungsinstitut für Vor- und Frühgeschichte, 1997 611

Bewertung der wissenschaftlichen Arbeit des Römisch-Germanischen Zentralmuseums,Forschungsinstitut für Vor- und Frühgeschichte, vorgenommen von einer internationalenFachkommission im Auftrag des Verwaltungsrates 769

Tafeln 47-62

V

ELAINE TURNER

ARIENDORF

QUATERNARY DEPOSITS AND PALAEOLITHIC EXCAVATIONS INTHE KARL SCHNEIDER GRAVEL PIT

WITH CONTRIBUTIONS FROM

WOLFGANG BOENIGK, MANFRED FRECHEN, MATTHIJS VAN KOLFSCHOTEN,

ELISABETH SCHNEPP, ERNST SEFKOV AND KAREL STEENSMA

This article id dedicated to Lisa Maskell(30.4.1914-29.8.1998), the founder of the

Gerda Henkel Stiftung.

Preface 5 K. STEENSMA TH. VAN KOLFSCHOTEN

The Middle Pleistocene (Saalian) Smaller MammalsAcknowledgements 5 (Insectivora, Rodentia) from Ariendorf 53

E. TURNER E TURNER

Location and Topographic Position of the Karl The Larger Vertebrate FaunaSchneider Gravel Pit at Ariendorf 6 from the Schneider GraVel Quarry at Ariendorf 69

E. TURNER

The History of Research and Excavation at Ariendorf E. TURNER

from 1970-1990 The archaeological horizons at Ariendorf

W. BOENIGR . M. FRECHEN — The Ariendorf 1 Archaeological Horizon 92Stratigraphie des Pleistozänprofils Ariendorf amMittelrhein 26 — The Ariendorf 2 Archaeological Horizon 122

E. SCHNEPP — The Ariendorf 3 Archaeological Horizon 173Paläomagnetische Untersuchung der Lößdeckschichten bei Ariendorf 37

E. TURNER

E. SEFKOV Summary 175Geologische Untersuchungen der Ariendorf 1 —

und Ariendorf 2 — Fundschichten 48 References 185

3

CONTRIBUTORS

Wolfgang Boenigk Elisabeth SchneppAbteilung Quartärgeologie, NIFB-GGA Arbeitsbereich GrubenhagenGeologisches Institut, Universität zu Köln OT RotenkirchenZülpicherstr. 49 37574 Einbeck, Germany50674 Köln, Germany

Ernst SefkovManfred Frechen Quarzwerke WitterschlickDepartment of Geography and Geology Schmale AlleeCEFQR 53347 Alfter bei Bonn, GermanyFrancis Close HallSwindon Road Karel SteensmaCheltenham, Huppeldijk 61United Kingdom GL 50 4 AZ 3543 Utrecht, The Netherlands

Matthijs van Kolfschoten Elaine TurnerRijksuniversiteit Leiden Forschungsbereich AltsteinzeitArcheologisch Centrum des Römisch~Germanischen ZentralmuseumsPostbus 9515 Schloß Monrepos2300 RA Leiden, The Netherlands 56567 Neuwied, Germany

4

PREFACE

About one kilometre to the north of Bad Hönningen and above the village of Ariendorf in the CentralRhineland of western Germany, are several quarries where gravel from the terraces of the Rhine Riverhas been extracted. In the largest of these, the Karl Schneider quarry, gravels belonging to a younger phase of the Middle Terrace Sequence, called the »Leubsdorf Terrace«, are currently being worked.The Middle Terrace gravels attain a depth of thirty metres in the quarry and arc overlain by up to fifteenmetres of cover-deposits consisting mainly of sand and loess with intercalated palaeosols and tephra horizons. Brunnacker (in: Brunnacker et al., 1975) identified three loess beds above the gravels and referred interglacial deposits, stratified between the gravels and the loess-cover, to the »Ariendorf Interglacial« named after this site. Today, at least four separate phases of accumulation relating to four coldwarm cycies can be recognized in the cover series (Haesaerts, 1990).Fossils from the Schneider quarry were first reported in 1970, when quarry machines cut through achannel-infill feature at the base of the cover deposits. The remains of several species of larger vertebrates were recovered during a series of rescue investigations at this site in the period 1970-74. At thesame time, the first detailed geological studies of the cover deposits at Ariendorf were undertaken du-ring the course of which isolated lithic artefacts were recovered from loess exposures above the channel—infill.In 1981, quarry machines again revealed a layer of animal bones stratified in the loess cover deposits.This time it was possible to investigate the site, Ariendorf 2, fully. During the course of excavation twofurther archaeological horizons, Ariendorf 1 and 3, were revealed as cover deposits were quarried awayin other parts of the pit.Pleistocene sequences revealed in the Kärlich clay pit in the Neuwied Basin, along with the exposures inthe Schneider quarry at Ariendorf, arc important for the Quaternary stratigraphy of the Central Rhineland. The presence of three archaeological horizons in the cover series at Ariendorf makes this site offurther interest for Palaeolithic research.This publication presents the results of excavations carried out between 1981-83 to investigate the Anendorf 1-3 archaeological levels along with geological descriptions of the Ariendorf 1 and 2 horizons undertaken by Ernst Sefkov (then University of Cologne), the resuits of sampling for palaeomagnetic dating by Elisabeth Schnepp (University of Münster) and the resuits of sampling for micromammals byThijs van Kolfschoten (University of Leiden) and Karl Steensma (Utrecht).Preparation of this volume actually began in 1983, but had to be postponed until the summer of 1993. Insome ways postponing the Ariendorf publication turned out to be to its advantage. Thus, another paperpresented in this volume (Manfred Frechen and Wolfgang Boenigk, Chronostratigraphy and Thermoluminescence Dating) and submitted in 1995, and a series of papers about the site published in 1990, reflectfurther investigations undertaken at Ariendorf during the latten part of the 1980‘s and early 1990‘s. Notonly do these contributions show how Quaternary research, and in particular chronostratigraphical interpretations, progressed at the site long after excavation had ceased, but they also bring this publicationabout one of the most important Quaternary exposures in the Central Rhineland up to date.

ACKNOWLEDGEMENTS

1 would mostly like to thank the quarry owner Mr. Karl Schneider and his family. Mr. Schneider gavepermission for the excavations to take place on his property, often placed quarry machines at our disposal and accepted our presence in the ph for over two years with great patience and interest.

5

Mn 1. Martin reported the discovery of the fossils found in the early 1970‘s and Mr. Roth was responsihie for alerting our Institute in 1981.The inhabitants of Ariendorf and Bad Hönningen deserve special thanks. The local council in Bad Hönfingen, and in particular the Lord Mayor Mr. T. Gierling and Mr. D. Wolter (Verkehrsamt) provided friendly, unbureaucratic solutions to bureaucratic problems: Mr. Feltens and the Bad Hönningen Bauamtspeedily organized practical assistance in the form of site-cover, heating and hghting facilities for ourfirst winter campaign.Fa. Mertgen (Strassenhaus) provided us with scaffolding and roofing materials for the 1982 winter campaign.Baron and Baroness von Geyr kindly placed rooms in Arenfels Castle at the teams disposai for the duration of the 1982 summer campaign. 1 wouid also like to thank the castle warden, Mr. Kurz, for his assistance during this period.Martin Street and Robbie Braun excavated the test-pit in 1981 and thanks are also due to Martin Streetfor taking photographs in the field and preparing the photo montage.Anne Hidien-Schlachter completed most of the figures. W Willingstorfer inked the section drawing infigs. 38 after sketches made in the field and Gabriele Rutkowski drew the lithic artefacts in figs. 42-54and 64-69. 1 would like to thank Dr. W-E Bär (Schriftleitung Geowissenschaftliche Arbeit) for permission to use the section drawing in fig. 6. Irene Assmann typed in some of the contributions. Comparative zoological collections in the Naturmuseum und Forschungsinstitut Senckenberg, Frankfurt, andMuseum A. Koenig, Bonn, were used to identify the faunal remains and thanks go to Dr. G. Storch(Frankfurt) and Dr. Hütterer (Bonn) for their assistance.A last word of thanks must go to all the many other team members who helped mc to excavate in Anendorf and in particular those who braved the very cold and wet winters of 1981 and 1982.Ariendorf was one of the first of a series of important Palaeolithic sites in the Central Rhineland to beinvestigated by the Forschungsbereich Altsteinzeit in its early days. Special recognition is due to the director, Professor Gerhard Bosinski, for his support and advice over the years. Without his determinedefforts to organise continuing financial security, research at Ariendorf and at other sites could never havebeen completed.The Kreissparkasse Neuwied financed the preliminary excavation in 1981. Funding for field-work in1982-1983 and for the preparation of this publication in 1993-1994 was provided by the Gerda HenkelStiftung, Düsseldorf, and thanks arc due here to Frau Maskell.The 1981-1983 excavations at Ariendorf were carried out by the Forschungsstelle Altsteinzeit, at that timc part of the Institut für Ur-und Frühgeschichte, University of Cologne, on behalf of the Landesamtfür Denkmalpflege Rheinland-Pfalz, Abteilung Bodendenkmalpflege, Außenstelle Koblenz.

LOCATION AND TOPOGRAPHIC POSITION OF THE KARL SCHNEIDER

GRAVEL PIT AT ARIENDORF

(E. TURNER)

The Karl Schneider gravel quarry at Ariendorf is located in the Rhine Valley region of Rheinland-Pfalz(Rhineland-Palatinate), about 28km south of Bonn and 27 km north of Koblenz (fig. 1). The nearesttowns arc Bad Hönningen about 1 km to the south and Linz am Rhein some 5 km to the north. Thesite is named after the village of Ariendorf, which is located just to the north of the gravel pit at the confluence of the Ariendorf Stream and the Rhine River. The three excavated areas were all iocated within

6

Fig. 1 Map of the Central Rhineland region of Germany between Koblenz and Bonn, showing the location of Ariendorf andneighbouring towns and the Laacher See. M = ca. 1:300000.

the pit at Topographical Map Reference (Landesvermessungsamt Rheinland-Pfalz) TK 1:25000 5409Linz am Rhein r259 230 h560 000 (fig. 2).The site at Ariendorf is in a region of Devonian siate bedrock, referred to geologically as the Rhenish Shieldor Rhenish Massif, through which the Rhine River drains from South-East to North-West. Wedged between the Upper Rhine Graben and the Lower Rhenish Embayment, the Rhenish Massif has a West to eastlong axis (fig. 3) abuts onto the northern boundary of the Variscan foldbelt and includes the Ardennes, theEifel and the Rhenish Massif east of the Rhine River and its margins (Murawski et al., 1983).In 1927 Kossmat divided the Variscan Mountains of Central Europe into several zones; a zonation WhiChis still accepted today. He created the term Rhenohercynian for the zone in which the Rhenish Massif

7

\.

IJs~

Fig. 2 Map of the Rhine Valley between Bad Hönningen and Leubsdorf. The Karl Schneider quarry at Ariendorf is markedby the arrow. Taken from the Topographische Karte 1 :25000B1. Nr. 5409 Linz am Rhein (Ausschnitt vervielfältigt mit Genehmigung des Landcsvermessungsamtes Rheinland-Pfalz, Kontrollnummer 62/97 durch Römisch-Germanisches Zentralmuseum,

Mainz). —M 1:30000.

8

.4lpioe fold beit

Forrbnd folding

Boriod riff Valloyofiurassic age

Extinet riff vallevof0ligocene age

Riff fault, roactivatedduring Qaatornary

—Diroxtion ofstrain.starting 05 rifta

Seismotectonic baSt,disarota riffvalloy absent

Platrau upliffduriog PlioPleistocene

Quatcmaxy volcanjccruptions

Aseismic forTan,tbickness ofPlnistoceoc sediments

500

r000

Fig. 3 Geomorphology of the Rhine Graben and the Position of the Rhenohercynian Zone (Rhenish Massif). Adapted from Schirmer (cd.) 1990; fig. 4 (after Illies & Baumann,1982) and Murawski et al., 1983, fig. 2. Thick black linemarks northern boundary of the Variscan foldbelt. — ~

M = 1:10000 000.

(Rhine = rheno) and the Harz Mountains (Harz = hercynian) were located. The Rhenohercynian zoneconsists of folded series of Devonian and Lower Carboniferous members. The form of the Massif ismainly due to Variscan tectonic history, the strike of the fold axes of the main anticlines and synclinesand the whole structure of the Rhenohercynian zone of the Variscan Mountains being instrumental inproducing its elongated form.The main phase of massif uplift began at the end of the Oligocene and continued up to the present time(Meyer et al., 1983). Tertiary sediments arc almost only preserved in marginal areas; they occur as relictsin the Neuwied Basin region, for example, and as highest terrace deposits along the Rhine Valley. Du-ring the Pleistocene (= Quaternary) epoch there was a more intensive downcutting of the Rhine River.Deposits dating to this period can be seen in the gravels of the Rhine Terraces which arc often overlainby loesses with intercalated palaeosols and tephra (volcanic ashes), the latter originating from extinctvolcanoes of the East Eifel Volcanic Field, centred around the Laacher See and located some12 kilometres away from Ariendorf on the left bank of the Rhine (fig. 1),The gravel-pit (referred to as Ariendorf) is located on a 5mal1 plateau of land known as »Burgland«,the eastern edge of the Rhine River valley (Pl. 1). The plateau is the southernmost tip of a levelled offMiddle Rhine Terrace (Leubsdorf Terrace) which stretches from Leubsdorf to Bad Hönningen between120 and 140 m OD and about 60 m above the present-day valley floor. The terrace is characterized byoutcrops of Devonian siate which form the steep Rhine Valley sides. Several small strearns dissect the

9

~\6~ 4

r ~s Y~—~

~N 1

~ ~~

~ ‚ \

~‚

~ ~~

~Q

Ø~J\N

~fe~

~ BAD

Fig. 4 Topography of the Rhine Valley and the Burgland plateau. Taken from the Topographische Karte 1:50000 Bl. Nr. L 5508Bad Neuenahr-Ahrweiler (Orohydrographische Ausgabe). (Ausschnitt vervielfältigt mit Genehmigung des Landesvermessungs

amtes Rheinland-Pfalz, Kontrollnummer 62/97 durch Römisch-Germanisches Zentralmuseum, Mainz). — M = 1:50 000.

10

Middle Terrace as they dram into the Rhine, and the Burgland plateau is bounded by the valley of theAriendorf Stream to the north and to the south by the valleys of the Moor and Staier Streams and thewidening of the Rhine valley itseif around Bad Hönningen (fig. 4).There is also evidence for two smaller, nowadays dry, valleys dose to the site. One is located on the northern edge of the plateau and must have drained into the Ariendorf Stream; the second dry valley, alongwhich the lane from Arenfels Castle to the sheep-pen (Schafstall) now runs, dissects the southern plateau edge (fig. 2 and 4). (E.T)

THE HISTORY OF RESEARCH AND EXCAVATION AT ARIENDORF

FROM 1970-1990

(E. TURNER)

Gravel extraction at Ariendorf

The history of Quaternary research at Ariendorf began with the opening up of the pit for gravel extraction in 1969. Gravel is used commercially for the cement industry, and approximately 15,000 cubicmetres of cement arc produced annually by the Karl Schneider firm. The quarry was originally workedin a southerly direction parallel to the Rhine Valley. Over the last few years, quarrying has progressedinland over the Burgland plateau; small strips of farm-land parallel to the quarry face being purchasedand worked out before the next strip of land is bought. At the beginning of the 1980‘s, the working faceof the quarry was some 200 m long (Pl. 2).Gravel extraction begins with the removal of the loess cover deposits. This is quite a long process as theloess »overburden« reaches a depth of some 15 m along the length of the quarry face. The quarrying»team« consists of a JCB and one or two lorries which work the deposits down in three »steps«, eachstep corresponding roughly to one of the three main loess beds. Loess is shovelled away by the JCB,dumped directly into a waiting lorry, driven away and tipped as back-fill into those areas of the pitwhere gravel has already been removed. This process continues until the surface of the gravel has beenreached, and usually an up to 50 m broad strip is prepared in this manner along the quarry face. The gravel is then loosened by running strong chains fixed to a winch up and down the almost vertical face ofthe gravel bed. Avalanches of pebbles roll down the face of the gravel bed and collect at its base wherethey arc simply bulldozed together and transported to the processing plant.

1970-1974: The initial phase of research

Initial research at Ariendorf was sparked off in 1970 by the discovery of fossil faunal remains whichdame to light during the removal of loess dover deposits in the quarry. The finds came mainly from channel-infill sediments at the base of the loess cover. Members of the team excavating at Gönnersdorf under the direction of Professor Gerhard Bosinski monitored the Ariendorf site until 1974. During this period, Bosinski encouraged other scientists to examine the exposures at Ariendorf in more detail. The results of investigations by geologists (Prof. Brunnacker and Dr. W. Boenigk, University of Cologne), malacologists (J. J. Puiss~gur), palaeontologists (E Poplin, Natural History Museum, Paris) and archaeologists (H. Löhr, Tübingen University) were published in 1975 and integrated into a first, detailed pro

11

ject aimed at establishing a stratigraphical sequence for the Quaternary of the Central Rhineland basedon exposures known at that time at Kärlich (Brunnacker, 1971), Leutesdorf (Brunnacker et al., 1974) andGönnersdorf (Brunnacker [ed.] 1978).Altogether, exposures in five pits around Ariendorf were studied (Brunnacker et al., 1975, Abb. 1). Inpit A, Upper Terrace deposits were exposed, in pits B, D and E, Middle, or to use the name given in thisregion, »Leubsdorf« Terrace deposits and in pit C, lowest Middle Terrace deposits. Fig. 5 is taken fromthe 1975 publication and shows Quaternary deposits exposed in the main Karl Schneider pit (pit B inBrunnacker et al., 1975) at the beginning of the 1970‘s. The exposures were described as follows.

Fluvio-glacial series

At the base of the exposures, up to 30 rn of fluviatile deposits (= fluviatile Folge) frorn the Rhine Middle Terrace or Leubsdorf Terrace, arc stratified unconformably on top of the Devonian slate bed-rock.The gravels arc stratified fluvio-glacial sediments, which accumulated in a valley cut probably by »Büdel‘s Eisrind effect« into the Devonian bed-rock prior to gravel deposition (Brunnacker et al., 1975).According to Büdel, the periglazial zone, and in particular the frost-shattered rock zone, is an area characterized by extreme downcutting by rivers and streams (Büdel, 1969; 1977). During the period of highdischarge associated with the spring melt, frost-shattered rock, normally frozen in winter in the activepermafrost layer, is freed and moves by solifluction (mass wasting) processes from the valley walls into

the river channels. Because of the increase in bad, the river degenerates (anastomosis) resulting in thedispiacement of gravel banks over the full breadth of the valley fboor and more intensive scouring of thevalley fboor and sides.Usually the detrital or bed bad of a river provides the tools with which the flowing water can abradesolid rock. This whole process is speeded up in periglacial zones because:i) the rock of the upper permafrost zone is frost-shattered (the so-called »Eisrinde«), thus reducing the

amount of primary breaking up that the river has to undertake. The river only has to thaw theEisrinde, whereby a water temperature of up to 5,8 C is necessary, and the material can be transported away and used directly for downcutting. This is the »Eisrinden effect« formulated by Büdcl, based on his observations of rivers in the periglacial regions in Spitzbergen.

ii) ~fl large rivers water freezes in winter not only on the surface, but also along the edges and the bottom of the bed. At this stage, the river water flows through an ice tunnel. During the spring thaw,frozen ice-masses at the bed risc up and in doing so, tear away chunks of rock, which arc also incorporated into the bed bad.

Büdel‘s theory that Pleistocene river downcutting was mainly due to the »Eisrinde-effect« was critici—zed by, amongst others, Rohdenburg (1968), who saw the drop in sea-level as being more likely the factor responsible for extensive valley formation in the perigbacial regions of Pleistocene Europe (Weise,1983).A first volcanic ash bayer (T1) was recorded in the upper part of the gravel bed at Ariendorf, where itcould be seen to fill out ice-wedge casts. Above the tephra, the fluviatile member consists of partiallycryoturbated gravel and sandy components and hill-wash materials indicating that apart from occasional phases of flooding, the main period of fluviatile activity had ceased towards the end of this GoldStage. The fluviatile series ends with a high-flood boam which shows in its mottbed appearance onsetting pedogenic processes. Gleying indicates that during this final phase the ground water-table was stillhigh.

Ariendorf Interglacial

A series of weathered volcanic ashes and pumices (TII-IX) was stratified directly above the high-floodloam. According to Brunnacker et ab. (1975) the tephras showed considerable synsedimentary loamification, representing a continuation of the pedogenic processes already observed in the high flood-boam.

12

On the basis of this the tephras were assigned in the main by Brunnacker to an interglacial phase, the»Ariendorf Interglacial« named after this site (ibid., 102).The uppermost deposits — the frost-shattered T VII ash, overlain by the pseudogleyed T VIII ash (gleying being again an indication of pedogenic processes) — reflected a transition to the following cold phase under oscillating climatic conditions.Poplin (in: Brunnacker et al., 1975, 117) found remains of several tree-leaves preserved as prints on thepeds of the T V tephra. The leaves are no longer available for study, but apparently resembled those ofbeech (Fagus), oak (Quercus) and hornbeam (Carpinus), in other words a typical mixed oak forest spectrum. Leaf prints from deciduous trees found in 1983 in the same tephra series were generally toopoorly-preserved to be identified to species (Pl. 2).

The loess cover-series

During 1971-72, three loess beds, stratified unconformably above the Ariendorf Interglacial deposits,were recognized in the cover-series. The oldest of these, Loess Bed 1 (= Löß-Decke 1, Brunnacker et al.,1975) was described as a sandy, carbonate-rich deposit in which two tephras (T X and XI) were stratified. Loess Bed II (= Löß-Decke II, ibid.) was, on the other hand, a loess bw in carbonate content, uponwhich a palaeosol had formed (Bt horizon of a Parabraunerde or orthic luvisol). The youngest deposit,Loess Bed III (= Löß-Decke III, ibid.), was stratified at the top of the cover series.The absence of a palaeosol at the top of Loess Bed 1 meant that the older loess couldn‘t be defined as aseparate phase of deposition at first, even though the description of this bed as a river-bank loess facies(ibid., 1975, 103) and the fragmentary remains of a reworked interglacial molluscan fauna at the base ofBed II hinted at the contrary. Finally in 1974, the in situ calcium carbonate (Cc) horizon of a palaeosolwas exposed, stratified in a position equivalent to the fossil soil missing between Loess Beds I and II andthus showing that Loess Bed 1 indeed represented a separate depositional phase.Sampling for molluscs in Loess Bed II (Puiss~gur in: Brunnacker et al., 1975) produced a Pupilla misscorum fauna in which species indicative of temperate climate, such as Vallonia costata and Vallonia pulchella were also present. The size of the Vallonia pulchella shells indicated the variety excentrica, whichinhabits grassy, sunny siopes or the van ety petricola, an indicator of steppic conditions. A colder, Columella columella/Pupilla loessica fauna was recovered at the base of Loess Bed II. On the whole the molluscan faunas from Bed II were very similar to those from the channel-infill (see below), and indicatedrelatively cold and very dry climatic conditions during this phase of loess deposition. Fragmentarymains of interglacial species were also recovered and represent a warm phase fauna reworked into theloess deposits.Brunnacker (et al., 1975, 104) noted that the Bt horizon at the top of Loess Bed II appeared to be subdivided in places by a lighter layer, similar in appearance to an Al horizon. The palaeosol had been covered first by reworked sediments above which pumice was exposed, which in turn had been partlyreworked into the overlying parautochthonous humic deposit. Brunnacker described the pumice as the»Metternich Tuff-Horizont« after pumice deposits in Koblenz-Metternich (Brunnacker et al., 1975, 106;Löhr u. Brunnacker, 1974). The humic horizon or horizons — a very diffuse boundary was apparent —

consisted mainly of a dark-brown, clayey loam sediment.The molluscan faunas with Arianta arbustorum, a high percentage of Pupilla muscorum and Valloniacostata, suggested alternating phases of cool and damp and cool and very dry, climatic conditions duringthe formation of the humic horizon. The presence of Chondrula tridens, a reduction in the number ofspecies present and a high proportion of Pupilla muscorum (94.5%) in the uppermost humic levels marked onsetting Glacial conditions although, rather surprisingly, true cold elements were absent in the fauna (Puiss~gur in: Brunnacker et al., 1975, 114).The loess of Bed III is the thickest of the cover series, attaining a depth of 8,5 m in a section recorded in1971. A brown, slightly humic horizon and a greyish zone represented breaks in the deposition of BedIII loess.

13

Faunal remains from the channel-inf iii

Forty-four faunal remains from several species of larger mammal were listed by Poplin as being foundbetween 1970-72 (in: Brunnacker et al., 1975, 118). The bulk of the finds came from a channel-infill atthe base of the loess cover-series. The channel had cut into the Ariendorf Interglacial deposits and wasfilled with loessic material in which remains of woolly rhinoceros Coelodonta antiquitatis, horse Equussp., giant deer Megaloceros cf. giganteus, reindeer Rangifer tarandus and mammoth Mammutbus trogontherii-prirnigenius were also embedded.Poplin concluded that the dominance of large herbivores in the fauna indicated a steppe environment,whereby reindeer showed that the climate must have been cold. A molluscan fauna, recovered from samples taken dose to the mammoth remains in the channel deposits and indicative of cold, dry conditionssupported this theory. Poplin suggested that the channel assemblage was comparable in age with theMain Mammoth Gravels at Steinheim, thought (sensu Poplin) to have been deposited during the Saaleor Penultimate Glaciation. In the same paper, Brunnacker and others remarked that current investigations being undertaken at Steinheim indicated an older age, the Third Gold Stage BP, for the Mammoth Gravels (Brunnacker et al., 1975, 136),

Faunal remains from the loess cover-series

At the same time, a few faunal remains were recovered from the loess beds at the site. Horse and mammoth were recorded from Loess Bed II and the remains of woolly rhinoceros, horse, a large bovine Bossp. or Bison sp., red deer Cervus elaphus and mammoth were found in the humic horizon at the base ofLoess Bed III. With reference to the finds from Bed III, Poplin remarked that the size of the horse andthe form of the mammoth molars indicated deposition of the fauna somewhere between the end of theLast or Eemian Interglacial and the middle of the Weichselian Gold Stage.

Lithic artefacts from the loess cover-series

Löhr described two lithic artefacts from the cover deposits in the ph (in: Brunnacker et al., 1975, 128ff.).The first artefact was a quartzite core blank from a Middle Palaeolithic prepared core. lt was discovercd on a ledge left behind after quarrying and was probably derived from one of the upper loess beds(Loess Bed II or III); it was thought to be younger in age than the tephra T XI in Loess bed 1.The second artefact was a transverse side scraper made from Tertiary quartzite. lt was patinated, retouched distally and showed signs of light abrasion. Also unstratified, the find was probably derived fromthe humic horizon at the base of Loess Bed III, as the humic soil and yellow-grey carbonate concretions adhering to the find, indicated. Lithic artefacts were not found in association with the faunal remainsfrom the channel-infill deposit.

Surnmary and age of the deposits in the Karl Schneider quarry

Thus, the initial research at Ariendorf in the early 1970‘s showed the presence of three loess beds, representing three separate phases of loess deposition, stratified above the Ariendorf Interglacial depositswhich in turn were stratified above the fluvio-glacial series of the Middle or Leubsdorf Terrace.The relationship between Loess Bed 1 and the channel-infill sediment was not fully dlear at the time.However, the bw carbonate content of the channel deposits indicated that its fill comprised reworked sediment from Loess Bed 1 and consequently both units were classed provisionally together in the1975 report. Brunnacker suggested later (Bosinski, Brunnacker and Turner, 1983, 160) that the channel sediments may have been deposited during a younger phase of the cold stage represented by LoessBed 1.Even at this early stage, it was dlear that the Ariendorf sequence was by no means complete. At least two

14

major hiatuses, the first between the Ariendorf Intergiacial tephras and the ioess-cover series and the second between Loess Beds 1 and II had aiready been recognized.Based on comparisons with terrace stratigraphy in the Lower Rhine region, the dominance of the heavy mineral Pyroxene particularly at the base of graveis in the glacio-fiuvial sequence (Frechen u. Heide,1970; Razi-Rad, 1976) and the three overlying strata, the deposition of the Leubsdorf Terrace gravels wasplaced in the latter part of the Fourth Gold Stage BP. This agreed weil with Potassium-Argon absolutedates of about 320 000±50 000 BP given by Frechen and Lippolt (1965) for the Selbergit vulcanicity inthe Central Rhineland, to which the tephra of the Ariendorf Interglacial series belonged.Brunnacker (et al., 1975, 136) concluded that the Leubsdorf Terrace was the equivalent of Unit Gb atKärlich, in which the volcanic mineral Pyroxene also occurred, and was younger than the locally-namedLeutesdorf Interglacial, thought at the time to represent the fourth warm phase BP in this area.Gollagen G14 from a bovine bone found in the humic layer at the base of Loess Bed III was dated to older than 31 000 BP (Lyon 630) which confirmed the stratigraphical/palaeontological interpretation thatthe youngest loess at Ariendorf was deposited during the Last or Weichselian Gold Stage.

Bibus‘ study in 1980

In 1980, Erhard Bibus presented bis study entitled »Zur Relief-, Boden- und Sedimententwicklung amunteren Mittelrhein« as the first monograph of the Frankfurt Geosciences Series. He also described thesequence in the Karl Schneider quarry at Ariendorf (1980, 139ff., fig. 23 = fig. 6 in this publication). Ingeneral, the exposures that Bibus saw at Ariendorf were much the same as those described by Brunnacker and others in 1975. However, Bibus‘ interpretation of the site differed quite substantially in so-mc cases.

The fluvio-glacial series

Bibus referred to the fluvio-glacial series at Ariendorf as the tRS Terrace (or »middle« Middle Terrace)(fig. 6, layers 1, 2 and 4). Bibus confirmed the earlier evidence at the site of increasing regional volcanicactivity, as shown in both the dominance of the volcanic heavy mineral Pyroxene in the gravels and thepresence of tephra stratified within the upper part of the fluvio-glacial sequence (fig. 6, layer 3). Bibuspointed out that large expanses of tephra associated with the last phase of tRg gravel deposition bad beenrecorded between Ariendorf and Leubsdorf in the early 1930‘s by Wilckens (1932), who described thetephra as a »Leucite-Phonolite Tuff«.Bibus did not, however, detect any signs of the pedogenic processes which Brunnacker described for thehigh flood loam exposed at the top of the fluvio-glacial series (fig. 6, layer 5), a point which led him tocall into question the identity and even the very existence of an »Ariendorf Interglacial«.

Ariendorf Interglacial

Although the tephra deposits stratified above the high flood loam were still visible (fig. 6, layers 6-10),Bibus did not agree with Brunnackers‘ interpretation that they belonged to an interglacial phase, let abne that the Karl Schneider quarry qualified as the »type-site« for such a warm phase. He writes:

»Wenngleich der unterste Abschnitt der Tuffschicht zersetzt ist, so kann ich mich nicht der Auffassungvon Brunnacker (1975, 135) anschließen, daß es sich um eine zweifelsfrei interglaziale Bodenbildunghandelt, die als locus typicus für das Ariendorfer Interglazial anzusehen sei.« (Bibus, 1980: 142).

Regarding the upper tephra deposits, which according to Brunnacker and others (1975) bebonged to theinterglacial phase but also showed evidence of frost-working due to the onsetting Glacial conditions ofthe folbowing cold stage, Bibus stated:

15

NW 20Cm SE NE ISOm SWVlll.Pof II Löll-Decke 111)

l.Protil V1l.Profil ViProfil lliProtiUTuff ll—IXI fl.Profil V Pofil

~ ~lSchotter) ~lLöl3-Deckelll) ‘gLön-Decke II) IV.Profil / 1 Tuff il-Vill) ([.dll - Deckel)m —_--_--~-_--------——-—_-~-__j~J~ne)N N .. . . .

Lbfl-DcckcllI . . . ~-r‘~~1

II ~ Artefukt~~— ~linsit~~~

°~~° Hoc~fl~[eh~ :RI;n~n~u tu ~ 0 0:~_: ~ T ~~TXI ~

:

00 ~ 0~ ~ .0

0Lt. 0 0

0

0> 0 o

•0 ~•~•

0 0

~0 :°

0.0. ~

0 00.0 .0

100- Devon

Fig. 5 Deposits in the Karl Schneider quarry exposed in 1970-1974. After Brunnacker et al., 1975; fig. 2.

»Auch für die meisten hangenden Tuffiagen nehmen Brunnacker et al., (1975, 102) eine Entstehungim »Ariendorfer Interglazial« an. Diese Tuffe zeigen jedoch keinerlei Anzeichen einer warmzeitlichen pedogenen Überprägung, sondern sogar schwache Periglazialerscheinungung.«(Bibus, 1980,142).

Finally, in Bibus‘s opinion, the reddish colouration of the basal tephra layer (fig. 6, layer 6) was due tono more than the typical mottling produced by the movement of free iron under waterlogged (anaerobic) conditions.His final words on the Ariendorf Interglacial were as follows:

»Es liegen damit im Profil 1 (Schneider quarry) keine sichere Hinweise vor, daß der obere Bimstuffin einem Interglazial (»Ariendorfer Interglazial« sensu Brunnacker et al., 1975, 102) zur Ablagerunggelangt ist.« (Bibus, 1980, 147: this authors italics).

The differing opinions about the deposits between the upper part of the fluvio-glacial series and the baseof the loess cover continued to be the subject of discussion into the early eighties (see below). The onlypoint concerning the »Ariendorf Interglacial« upon which both Bibus and the earlier team of researchersagreed, was the presence of a significant hiatus between the tephra deposits and the loess cover series, ahiatus which became more evident towards the southern end of the quarry where the tephra depositshad been extensively eroded (Bibus, 1980, 143).

16

32 rezenter A~- und B,-Horizont31 Jungwürm-Naßboden E~ oder E330 Jungwürm-Naßboden E229 Jungwürm-Naßboden E,28 Umlagerungszone über Lohner Boden mit Rambacher

Tuff27 Lohner Boden, z.T. zweigeteilt oder umgelagert26 Niedereschbacher Zone25 Mosbacher Humuszone, z.T. mit Bims, oberer Abschnitt24 Bimstuff Typus Glees, bzw. Metternicher Tuff23 Mosbacher Humuszone, unterer Abschnitt22 Fließerde, z.T. in Eiskeil21 1. fB,, Eem-Boden20 Jungriß-Naßboden, schwach verbraunt19 Jungriß-Naßboden, schwach verbraunt18 sandige Kiesbänder17 Jungriß-Naßböden (?)16 brauner kiesiger Sand

15 schwarzer Basaittuff, z.T. umgelagert14 rötlichbrauner lehmiger Sand, B~-Horizont~)13 gelber feinsandiger Schluff, feingeschichtet, Schwemm

löß12 grobsandiger Kies, Rinnenfüllung11 grünlichgrauer Staubtuff mit Basaltschlacken und Bims1 la Bimstuff, körnig, mit Basaltschlacken10 grünlichgrauer plattiger Tuff, durch Frosteinwirkung

zerbr.9 graue verfestigte Tuffbank8 bräunlichgrauer grober Bims7 grauer feiner Tuff, verfestigt, porös, geschichtet6 rostbrauner-bräunlichgrauer Bimstuff, zersetzt5 braungelber, schluffigei~ kiesiger Hochflutlehm4 brauner Kies, unsortiert3 Bimstuff, verwürgt2 graubrauner Kies, feingeschichtet1 fahlrötlichei~ unten dunkelgrauer Kies

N

3

4

s

~z ~ = = ==29

.~... 28‘.~~‘. ‘.4 ‘.4

~~rWtZ‘2~~ 27 ‚.. ‘..~ — ~ ‚—‚ —J .-~ .~ ~‘ ‚-4 _J —4 nJ_

‚1 ~~~UIJ ii ~ .~t!... ~~i‘:1

nicht zugänglich

= = = = = = = = = = = = = = = = == = 20 = = = = = = = = = = = = = = = = = = = = == = = = === =

19

- -‚..‘. .4‘. 18 —. — — ‘.. = = =

14

15

17

18

0 0 0 0.‘. ~ ~‚..00 ‚.~ ~_.‚.‘. ‘..‘..4 0 .‚. 0 * ~ 0 o 0 . . 0 -. - - .0 — -. — -~ — — - 0 0~ 0 0

0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 000 fl‘. ~ ‚.‘. ‚.oOO 0 ‚.0.40.4 0 ~ o‘.

‘-:- :: W.~ O:.~ ~~.—

25

c:.4 .~. ‘~ . _ . ~* ~. ~S ~ .c~,1 . c~ ca .~ .~ ~ ~ .ca .~ .~ .c~.ca• ~ ~).ca.ca~~.

75 lOOm

~) Bei der Rückverlegung der Wand war unter dem Eem-Boden ein 2. fossiler B~-Horizont mit Ca-Horizont aufgeschlossen, der inden Eem-Boden einmündete.

Fig. 6 Deposits in the Karl Schneider quarry recorded by Bibus. After Bibus 1980; fig. 23.

The loess cover-series

In 1976-77, Bibus recorded the loess-cover series at Ariendorf (1980, 201), thus completing his earlier researches at the quarry where, together with Semmel, he had recorded the Loess Bed III deposits in detail (Bibus u. Semmel, 1977). In autumn 1976, the Bt and Cc horizon of a second palaeosol were revealed

17

in a recently-cut access track. This older fossil soil was not visible during the earlier investigations; according to Bibus it was stratified below and merged into the main palaeosol (Eemian) which had formedon top of Loess Bed II (fig. 6, below layer 21; position marked with an asterix). This confirmed, according to Bibus, Brunnackers‘ sub-division of the older loess into two separate beds (1980, 202).Bibus recognised at least two and possibly three horizons showing evidence of weak pedogenic processes stratified below the palaeosol at the top of Loess Bed II (fig. 6, layers 17, 19 and 20). Although theupper two horizons did not have all the characteristics associated with typical »Jungriß-Naßböden«, Bibus (1980, 202) saw a probable correlation between these soils and those of the »Bruchköbeler« soilcomplex (younger Riss = Saalian Cold Stage soils). The loess below layer 19 (fig. 6) was reworked, as themany sand and gravel lenses and smaller gravel-filled channels clearly showed (fig. 6, layer 18).In the southern part of the quarry and at the base of the reworked loess, a distinct hiatus marked by agravel deposit was observed (fig. 6, layer 16). Stratified below this was a reworked black basaltic ash(fig. 6, layer 15) and closely associated with the ash a reddish-brown, loamy sand mixed (Bv-horizon)and a Cc horizon (fig. 6, layer 14). Bibus suggested that the Bv horizon could be the remains of thecond palaeosol exposed in 1976 and preserved here in a depression formed in the eroded tephra series.A sandy loess was stratified between these deposits and the tephra series of the »Ariendorf Interglacial«.

Loess Bed III

Bibus recognized a definite division of the humic horizon at the base of Loess Bed III into an upper andlower zone (fig. 6, layers 23 and 25), with the pumice layer which he described as the »Metternich« or»Glees« tephra (fig. 6, layer 24), stratified between the two. He referred to the lower humic zone as the»Mosbach Humuszone, unterer Abschnitt« and the upper zone as the »Mosbach Humuszone, obererAbschnitt« using terminology given to sequences in the Rhine-Main areas.Brunnacker and others had already noted the presence of at least two weakly-defined breaks in theloess sedimentation of Bed III. Bibus described the Loess Bed III sequence in more detail, recognizing Last Glacial marker horizons such as the Niedereschbacher Zone, Lohner soil with Rambachertephra, and three younger Würm (= Weichsel) Naßboden, the El, E2 and E3 or 5 horizons (fig. 6,layers 26-31).

In contrast to Brunnacker and others (1975) Bibus correlated the deposition of the Leubsdorf Terracegravels with the Third rather than the Fourth Cold Phase BP (1980, 203). He based his dating on theloess cover series, which he interpreted as representing only two cold stages (1980, 261), thus:

Holocene soilLoess Bed III = Last or Weichselian Cold StagePalaeosol Last or Eemian InterglacialLoess = Second Cold StageBv horizon = Second InterglacialLeubsdorf Terrace = Third Cold Stage

The archaeological investigations undertaken between 1981-83

Seven years after monitoring of the channel-infill deposits had ceased, Mr. Roth from Neuwied reported that bones had again been found during loess quarrying in the Karl Schneider pit. The lapse of timebetween fossils being reported probably meant that finds had been overlooked as loess was removed; themethods employed to quarry the loess cover in the pit being, unfortunately, not particularly conduciveto either find observation or recovery.

18

Two days after this message was received, Gerhard Bosinski visited the quarry and noted a horizon offaunal remains in situ in the quarry face. The finds were stratified towards the top of Loess Bed II,roughly 50 cm below the base of the palaeosol which had formed on top of this bed. Unfortunately thebone layer had already been extensively cut by quarrying. A few elephant tusk fragments found at thebase of the exposures, and some pieces of bone in a loess dump on a quarry ledge above the bone layer,were the only evidence left behind at the site for the many finds already lost.The first lithic artefact was discovered amongst the bones only a few hours after a sondage had beenopened to investigate the site. Whereas the Gönnersdof team had to be content with monitoring the removal of the faunal remains in the channel-infill deposits in the early 70‘s, the archaeological importance of this new site meant that a rescue excavation had to be undertaken. Thus excavation began more or less straight away and continued through the winter, with a few breaks, into the following summer.During the course of investigation at this site (= Ariendorf 2), two further archaeological horizons, oneat the base of Loess Bed 1 (= Ariendorf 1) and one in the humic horizon at the base of Loess Bed III (=Ariendorf 3) were discovered as quarrying of the loess-cover deposits continued, The fact that three insitu archaeological horizons were exposed within a two-year period at Ariendorf probably gives us so-mc idea of the amount of archaeological and fossiliferous material that may have been removed over theyears from the end of the initial monitoring of the quarry in 1974 and the commencement of archaeological excavations undertaken in 1981.Two main interim reports were published about this phase (Bosinski, Brunnacker and Turner, 1983; Turner, 1986). Karl Brunnacker was present again on the geological front at Ariendorf during 198 1-83, andit was possible for hirn to fiu in some details about the stratigraphic sequences at the site due to the more extensive exposures in the quarry at this time (in: Bosinski, Brunnacker and Turner, 1983, 157ff., figs.2-3: fig. 7 in this report). However, the basic sequence of fluvio-glacial series of the Leubsdorf Terrace,followed by Ariendorf Interglacial deposits sensu Brunnacker and loess cover-series comprising threeseparate loess beds, rernained unchanged.

Ariendorf Interglacial

New, however, to the Ariendorf Interglacial deposits (= high flood loam; »Selbergit« tephra series) were a thin gravel band and a reddish-brown sandy horizon stratified above the upperrnost tephra layerwhere previously a major hiatus had been recorded. Brunnacker stated that the red-brown colourationof the sand was due to soil formation processes and rernained adamant in his opinion that these pedogenic processes had also affected the underlying tephra. A phenomenorn which, as Brunnacker succintly put it, »E. Bibus (1980) entweder bei seinem flüchtigen Besuch nicht beobachten konnte oder nichtzu interpretieren vermochte.« (Bosinski, Brunnacker and Turner, 1983, 159).The upper boundary of the Ariendorf Interglacial deposits was extensively cryoturbated, a feature often observed by myseif and others during the course of investigations during 1981-83 and also figuredin the work by Weise (1983, 70, fig. 39).

Loess Bed 1

A reddish-brown Bv horizon, exposed in places to a depth of some 70 cm, was recorded at the top ofLoess Bed 1. Prior to this, warm stage deposits at the top of Bed 1 were either missing (hiatus) or represented only by a calcium carbonate (Cc) horizon and the remains of a reworked interglacial molluscan fauna (Brunnacker et al., 1975). Whether the Bv horizon is the same as the one that Bibus recorded, which from its position in his section could belong to Loess Bed 1(1980, 202-203, fig. 6 in thisreport and see above) is difficult to say, as Bibus only refers briefly to the Bv in his section description and Brunnacker rnakes no reference to the fact that Bibus even saw such a deposit in the loess cover-series.

19

Stratigraphy Stratigraphy ofthe Lower Rhine Terraces

Holocenexl000yeors

Lower TerraceLoess Bed III (Last Cold Stage = Würm/Weichsel Glaciation)

l‘iumic horizons Ariendorf 31(111 1 1 1 1 111111

Metternich pumice100 —

Riss/Würm or) Eemian Interglacial

Loess Bed ~ __________________= Middle Terrace IV(Penultimate Cold Stage Riss/Saale Glaciation)

L_ Ariendorf 2Devonian siate

200 reworked deposits <— Bv material

~ Interglacial

Cchorizon

Loess Bed 1 = Middle Terrace III300 — (with reworked loess and locally (Third Cold Stage = Saale Glaciation)

derived gravels in channel-infill)

cryoturbation Ariendorf 1— red-brown sand

“Selbergit“ tephra Ariendorfinterglacial Holstein Interglacial— high flood loam ___________________

local gravels400 — “Selbergit“ tephra ~‘ Go horizon

Middle Terrace IIRhine gravels (with Pyroxene) (Fourth Cold Stage = Elster Glaciation)

Fig. 7 Schematical section through the deposits exposed in the Karl Schneider quarry during archaeological investigationsdertaken in 1981-1983, their chronostratigraphical interpretation and the location of the Ariendorf 1-3 archaeological hori

zons. — Adapted from Brunnacker, Bosinski & Turner, 1983; fig. 2.

Loess Bed II

Interesting was the appearance of a tephra layer in Loess Bed II. The tephra was exposed after loess hadbeen quarried away around the Ariendorf 2 site in summer 1982. lt consisted of a thin, discontinuousband of loosely-packed black ash, stratified below the Ariendorf 2 horizon. Its irregularly pointedlower boundary was evidence of frost-action. Samples taken from this tephra and studied by Meijs inUtrecht, showed similarities in mineralogic content with the so-called »Brockentuff« in the Kärlich claypit (pers. comm., letter dated 8.09. 86). The tephra bears some similarities in appearance with the ash dcscribed by Bibus (fig. 6, layer 15).Thus, the stratigraphic interpretation of the Ariendorf sequence remained, according to Brunnacker, thesame as in 1975. In the 1983 publication he compared the Ariendorf sequence with terrace chronostratigraphy from the Lower Rhine area as follows (correlations of local sequences with known stratigraphical divisions of Northern Europe after Brunnacker et al. (1975):— the fluvio-glacial series of the Leubsdorf Terrace was the equivalent of the Middle Terrace II

(younger part) and was deposited during the Fourth Gold Stage BP or Elster Glaciation— the Ariendorf Interglacial may be the equivalent of the Holstein Interglacial— the sandy Loess Bed 1 was the equivalent of the Middle Terrace III and dated to the Third Gold Sta

ge BP or Saale Glaciation

20

— Loess Bed II was the equivalent of the Middle Terrace IV and was deposited during the Riss Glaciation or Penultimate Gold Stage BP

— the palaeosol at the top of Bed II was the equivalent of the Riss/Würm Interglacial or Eem Interglacial

— Loess Bed III dated to the Würm or Weichsel Glaciation (= Last Gold Stage) and was equivalent tothe Lower Rhine Terrace.

Following this, the archaeological horizons were dated as follows: Ariendorf 1, stratified at the base ofLoess Bed 1 was deposited during the Third or earlier Saalian Gold Stage, Ariendorf 2, stratified at thetop of Loess Bed II dated to the Penultimate Glaciation (presurnably Saalian Gold Stage) and Ariendorf3, located in the humic horizon at the base of Loess Bed III was deposited at the beginning of the Lastor Weichselian Gold Stage.

Absolute dating and new stratigraphical interpretations in the late 1980‘s and 1990‘s

In 1990, Wolfgang Schirmer edited and published an excursion guide for the 25th Scientific Meeting ofthe German Quaternary Union (deuqua) which took place frorn the 9th-l6th September 1990 in Düsseldorf. The excursion guide was intended from the beginning to be more than just the usual collectionof loose papers in a folder describing sites visited along the route and when it appeared, the »Rheingeschichte zwischen Mosel und Maas« proved to be an excellent reference work for many researchers active in the field of Quaternary sciences in the Rhineland. Reports about four archaeological sites in theGentral Rhineland area appeared in the guide and a series of short, hut important, contributions describing the resuits of recent research at Ariendorf were submitted by E. Turner, M. Frechen, P.Haesaerts, B. Hentzsch, Th. van Kolfschoten, P. v. d. Bogaard and H.-U. Schmincke.Hentzsch described the Middle Terrace gravel deposits in the Karl Schneider quarry as comprising twomain components. Gross-bedded sandy gravels deposited by a meandering river-system form the basalpart and coarse gravels arc stratified above these. Hentzsch also noted a tephra horizon (T1) stratified inthe upper part of the coarse gravels and, at the top of the fluvio-glacial series, local gravelly depositsoverlain by a high-flood loam marking the end of fluviatile activity.She writes that the high-flood loarn showed evidence of pedogenic processes which had been interruptedby the deposition of a further tephra horizon. Together with this palaeosol, a total of three palaeosolsare present above the fluvio-glacial series. The Leubsdorfer Terrace at Ariendorf thus belongs to theMiddle Terrace sequence of the Rhine River. Following this, gravel deposition took place during theFourth Gold Stage BP. The presence of the volcanic heavy mineral pyroxene throughout the gravel bed(Razi-Rad, 1976) placed gravel deposition at Ariendorf into the second half of the Fourth Gold Stage(Hentzsch, 1990).Haesaerts description of the loess cover-series presented, however, a cornpletely different interpretationof the stratigraphy at Ariendorf. Extensive quarrying in the southern part of the pit prior to 1988 enabled hirn to record the loess cover series in detail (Haesaerts, 1990, p. 112; fig. 2 and fig. 8 in this report).During quarrying, a new loessic unit had been revealed stratified between Loess Bed 1 and the uppermost tephra layer of the Ariendorf Interglacial.The loess, often referred to as »Haesaerts loess«, was dcscribed as a »two-fold sandy loess body, with gravelly layers at the base, on top of which a reddish multi-component Parabraunerde has developed« (ibid, p.ll2). Haesaerts also noted the presence of a secondParabraunerde, mentioned previously by Stremme (1985), stratified just below the upper »Selbergit« tephra of the Ariendorf Interglacial.Heasaerts writes »As the new stratigraphic sequence of the cover-deposits in the Schneider quarry encompass at least five climatic cycies, the Leubsdorf Terrace must be correlated with the sixth glacial period before present« (190:112). A date which, in his opinion, agrees not only with absolute dating of the

21

East 0 50 100 150 200 250 300m West

tephras of the Ariendorf Interglacial series but also the biostratigraphy of the micromammals fromAriendorf 1 and is consistent with the known chronology of the Rhine Middle Terraces.This interpretation is rather difficult to follow as only four climatic cycles are indicated in the cover deposits in Haesaerts‘s drawing of the section he saw at Ariendorf (fig. 8). These arc from top to base —

Holocene soil at the top of Loess Bed (=L.D.) III, Ariendorf 1 at the top of Loess Bed II, Ariendorf IIat the top of Loess Bed 1 (not indicated as not present in this section) and Ariendorf III at the top ofHaesaerts loess —. The warm phase deposits at the base of the cover series (Ariendorf IV=Ariendorf Interglacial) and the underlying gravels of the Leubsdorf Terrace certainly represent a fifth climatic cycle,but one which is not in the loess cover series (for further criticism of Haesaerts interpretation see reportFrechen and Boenigk, this volume).The identification of a fourth loess unit (Haesaerts loess) at the base of the cover-series shows that theAriendorf Interglacial and the Leubsdorf Terrace arc at least one stage older than previously thought andaccording to this, gravel deposition must have taken place during the Fifth Gold Stage BP at the latest.Hentzsch does not appear to have been informed about the discovery of a new loessic unit at Ariendorf,at least she makes no mention of this in her article (1990) and presumably her stratigraphical interpretation was based on information about the number of palaeosols in the loess cover series taken from anolder publication. Haesaerts reasons for dating the deposition of the Leubsdorf Terrace to the Sixth GoldStage BP arc not clear, particularly as even his own section drawing of the Ariendorf deposits does notillustrate his arguments. Thus, the resuits of the stratigraphical analyses undertaken at Ariendorf byHentzsch and Haesaerts arc contradictory and confusing.Let us turn now to the resuits of absolute dating at Ariendorf published in Schirmers guide. Several tephra horizons at Ariendorf were absolute dated by v. d. Bogaard and Schmincke (1990) using the singlecrystal laser method, a refined 40Ar/39Ar technique. The oldest tephra, ARI-DT1 (=T1?) is described asa heavily weathered and cryoturbated pumice horizon which has a maximal Laser age of about 490,000BP. Bogaard and Schmincke also sampled two pumice tephra from the Ariendorf Interglacial deposits.

Abb. 8 Schematical section of the quarry face at Ariendorf recorded by Haesaerts in 1988. Taken from W Schirmer (cd.) 1990,p. 113, fig. 2. The position of the archaeological horizons arc marked by large numbers.

22

Described as »Selbergit Tuff« in earlier reports about the site (Brunnacker et al., 1975), the two tephraare stratified above the high-flood loam and separated by an up to 25cm. thick palaeosol. The older tephra, ARI-DT2, has a maximal age of 451,000±6,000 BP. The younger tephra ARI-DT3, in which impressions of leaves were observed, was dated to around 410,000 BP. Both tephras were deposited duringthe Rieden eruptive phase. One tephra, probably ARI-DT3, has also been dated by the conventional4OAr/39Ar stepwise-degassing method to 419,000±18,000 BP (Fuhrmann, 1983; Lippolt et al., 1986).Based on the results of these two independent analyses, tephras which were deposited during the Arien-dorf Interglacial date this warm phase to between 410,000 and 45 1,000 BP.Bogaard and Schmincke (ibid) refer to localised lenses of reworked basaltic ash material (ARI-BT1)about one metre above ARI-DT3 and these may represent the same lense observed during excavation in1982 in Loess Bed II, sampled by Meijs (see page 18) and described by Bibus (1980; fig. 23, layer 15 andfig. 6 in this report).The pumice tephra stratified in the humic horizon at the base of Loess Bed III was also sampled. Thistephra, ARI-DT4, is described as a generally in situ, 15 cm. thick pumice horizon. In earlier reports thistephra is referred to as the »Metternich« pumice (see page 6). However, its mineral content, chemicalcomposition and the occurrence of regional metamorphic mica schist in the sample show that ARI-DT4was the distal equivalent of the Hüttenberg tephra of the Wehr volcano. The Hüttenberg tephra has beendated at source to around 215,000±4,000 BP. From its stratigraphical Position — sharp contact zone tothe underlying palaeosol at the top of Loess Bed II and diffuse upper boundary to the dark brown, humic layer — it was concluded that the pumice was deposited at the beginning of an interglacial phase.According to v.d. Bogaard and Schmincke (ibid.), the A-horizon of the soil which developed during thiswarm stage was located above the tephra whereby the Bt-horizon developed through the permeable pumice layer and was thus stratified below the tephra. Boenigk and Frechen (this report) contend this interpretation and state that the pumice was not deposited during an interglacial phase as it is stratified inthe humic zone, a layer which formed during an early glacial phase.Two independent series of thermoluminescence dates were taken in the loess beds. The reliable datessupported the theory that the loess of Bed III was deposited during the Last or Weichselian Gold Stage(see report Boenigk and Frechen, this volume; Frechen, 1990; Zöller, Stremme & Wagner, 1988).The biostratigraphy of certain species of larger and smaller mammals indicated that the faunas from Anendorf 1 and 2, were post-Holsteinian in age (Turner, 199Db; Kolfschoten, 199Db). The evolutionary stages observed on the molars of the genus Arvicola showed that both faunas were deposited during theSaalian Gold Stage, whereby the older fauna, Ariendorf 1 probably dated to an early phase of this coldstage. The youngest archaeological level, Ariendorf 3, was still regarded as early Weichselian in age, dueto its stratigraphical Position at the base of Loess Bed III (Turner 1990c, 1991), despite a date of about2 15,000 BP given for the Hüttenberg pumice stratified just below the Ariendorf 3 level.The initial reluctance of co-researchers to fully accept absolute dates produced by the single crystal Laser method is understandable when the brief history of this dating method in the Gentral Rhineland isconsidered. Laser dates from the first series of tephras sampled from sites in this region were considered too old. For example, the tephra ARI-DT1 at Ariendorf was dated at first to 710,000±2,000 (~d.Bogaard and Schmincke, 1988). According to this date, deposition of the ARI-DT1 tephra, stratifiedwithin the Leubsdorf Terrace, took place almost at the Matuyama-Brunhes boundary, which is usuallydated to around 730,000 BP. The same sample was analysed a second time and produced a maximal ageof 490,000 years (v.d. Bogaard and Schmincke, 1990), a substantial difference in age of some 220,000years. The tephra ARI-DT3 was dated to 442,000 ± 3,000 BP (v.d.Bogaard and Schmincke, 1988) and later to about 410,000 BP (v.d .Bogaard and Schmincke, 1990). lt is probable that some of the absolute dates published in 1990 will become slightly younger as this dating method is improved.The age of the Hüttenberg pumice was also regarded with scepticism because the date of 215,00±4,000BP did not fit into the accepted chronostratigraphy of the Ariendorf deposits and also due to the factthat the sample dated was not taken at Ariendorf, but dose to the source of this pumice in the Wehr volcano. In the early 1 990‘s, the Hüttenberg pumice deposit in Ariendorf was finally sampled and analysed.

23

According to Paul v.d, Bogaard (letter dated 6.1.95 and lecture given during the final meeting of theDFG-sponsored project »Quartär der Osteifel« injune, 1997), the as yet unpublished date for the Hüttenberg pumice at Ariendorf is very similar to the one given for this tephra at source, showing that partof the cover series in the quarry does appear to be older than previously thought.

A new stratigraphical interpretation of the Ariendorf sequence

In the final part of the history of research at Ariendorf, a new stratigraphical interpretation of the Arien-dorf sequence is described. By using absolute dates produced by the Laser technique and the (reliable)TL dates, the presence of a new loessic unit in the cover series and the relative ages given for the faunasfrom Ariendorf 1 and 2 as reference points, it was possible to produce a plausible, revised stratigraphyfor the Ariendorf sequence, even though it was not possible at this stage to give an exact age to everygeological layer exposed at the site (fig. 9).A tephra stratified in the Leubsdorf Terrace has been dated to about 490,000 years. This date gives only a maximal age for the Leubsdorf Terrace, gravel deposition probably took place at a date sometimeearlier than 490,000. Two tephras which were deposited during the Ariendorf Interglacial have been absolute dated. The oldest of the two has a maximal age of about 451,000 BP; it was probably depositedearlier than this date, but not later than 410,000 BP and 419,000 BP, these being dates given by two separate analyses for the younger tephra. The Ariendorf Interglacial is, according to the absolute dates, awarm phase dating to about 410,000-419,000 BP and not older than 45 1,000 BP.The Ariendorf Interglacial deposits are covered by three loess units with intercalated palaeosols —

Haesaerts loess, Loess Bed 1 and Loess Bed II — which represent three cold warm cycles. At the top ofthis sequence is the humic horizon in which the Hüttenberg pumice is stratified. This tephra has beendated absolutely to around 2 15,000 BP. The loess and palaeosols units thus represent a sequence of threeclimatic cycies dated to between 410,000 BP (youngest date for the Ariendorf Interglacial) and 2 15,000BP (age of the Hüttenberg pumice).The age of the Hüttenberg pumice indicates that the palaeosol at the top of Loess Bed II, previously assigned to the Last or Eemian Interglacial due to its stratigraphical position, is a stage older and now represents an interglacial phase within the Saalian Cold Stage. Thermoluminescence dates taken in LoessBed III support, however, the theory that the upper part of the loess overlying the humic horizon wasdeposited during the Last or Weichselian Gold Stage. The date of the Hüttenberg pumice and dates forthe loess of Bed III, indicate that a climatic cycle is missing between the humic deposit and the loess ofthe youngest unit in the cover series at Ariendorf.Assuming that each loess-palaeosol unit represents a glacial-interglacial cycle and taking into accountthat one cycle in the upper part of the section is missing, then at least five cycles are present in the loesscover series. The deposition of the Leubsdorf Terrace gravels could then be placed in the Sixth Gold Stage BP, as Haesaerts proposed in 1990 (but see also Boenigk and Frechen‘s interpretation of the loess Gover series on page 37).The new stratigraphical interpretations at Ariendorf also lead to a revision of the ages of the archaeolo—gical levels. According to the absolute dates, the deposits in which Ariendorf 1-3 arc located arc onestage older than previously thought. In the deuqua guide (Turner, 199Db) and in earlier reports (Turner1990c; 1991) Ariendorf 1, at the base of Loess Bed 1, was attributed to the beginning of the Saalian GoldStage, Ariendorf 2 in the upper part of Loess Bed II to the end of the Saalian Gold Stage and Ariendorf3 in the humic horizon, to the beginning of the Last or Gold Stage. The younger levels, Ariendorf 3 andAriendorf 2, which arc stratified dose to the Hüttenberg pumice, can probably be dated as follows. Anendorf 3 is located in the humic horizon, more or less directly above the Hüttenberg pumice: This levelappears to have been deposited at the beginning of a younger phase of the Saale Gold Stage. The Position of Ariendorf 2, in a loess bed below the Hüttenberg pumice, indicates that this level was probably

24

2;

~4~ii~r t~rr i4i~~

1 1 1 1 11J~LLLL J~LL

~Jllj]II III ~AR2I~ I~I~ ri1~1 11111

II II 1 IIk~~W0~ 1~~W

11111 111111

IIII ~AR1

III

ri JIJI 11111

III 1 II~“LU‘~LU ILL

TTTTTTTTTTTTTTr i rrrrrrrrrn HIUNIIIIIIIII

11111 11111 11111 I~ 11111 111111TTTTTTTTTTTTT

~OOc. O~O~0~ 2TTTTTTTTTTTTT

~Qoc,~Q~ o~ ~jc?ooor~‚6:.

— ~

LOESS BED II!

f~ Gravels ~llIll Palaeosol If~J Tephra flIJ~ Loess

Fig. 9 The revised stratigraphy, absolute dates and new chronological interpretation ot the sequence of deposits in the KarlSchneider quarry at Ariendorf.

HOLOCENE

WeichseJian Cold Stage(TL-Dating)

Younger Saalian CoId StageART-DT 4 Hütten berg Pumice —

21 5.000 ± 4.000 BP.Intra-Saalian Interglacial

Older Saalian Cold Stage

Post-Holsteinian

ART-DT 3ca. 410.000 BP.!

419.000 ± 18.000 BP.

ART-DT 2451.000 ± 6.000 BP.(maximal age)

ART-DT 1ca. 490.000 BP.

HIATUSHUMIC HORIZON

LOESS BED II

LOESS BED 1

“HAESAERTS“ LOESS

ARIEN DORF

LEUBSDORFTERRACE

25

deposited during an older phase of the Saale Cold Stage. The biostratigraphy of the fauna fromAriendorf 2 does not contradict a Saalian age for this level. The age of Ariendorf 1 is somewhat problematic as this level is not closely stratified to either the Hüttenberg pumice or the dated tephras of theAriendorf Interglacial. Ariendorf 1 is located in the middle of a series of loess-palaeosol units which aredated to between 410,000 BP and 215,000 BP. However, the biostratigraphy of certain of the larger andsmaller mammals from the Ariendorf 1 fauna shows that this level, and presumably Loess Bed 1, postdate the Holstein Interglacial sensu stricto. (E. T)

STRATIGRAPHIE DES MITTELPLEISTOZÄNPROFILS VON ARIENDORF

AM MITTELRHEIN

(w. BOENIGK M. FRECHEN)

Das von Brunnacker et al. (1975) geologisch untersuchte Pleistozänprofil Ariendorf gilt neben Kärlichund Miesenheim als eines der bedeutendsten Mitteipleistozänprofile des Mittelrheingebietes. In denletzten Jahren sind die Deckschichten der Kiesgrube der Fa. Karl Schneider in Ariendorf Ziel mehrererDatierungsstudien gewesen. Fuhrmann (1983; vgl. Lippolt, Fuhrmann u. Hradetzky 1986) datierte denoberen Selbergittuff mit der konventionellen 40Ar/39Ar-Methode, v. d. Bogaard u. Schmincke (1988) untersuchten die Bimstephren mit der 40Ar/39Ar-Einzelkristall-Methode. Thermolumineszenz-Alter anSedimenten der Löß-/Paläobödenabfolgen wurden in mehreren Arbeiten bestimmt (Balescu 1988; Zöller, Stremme u. Wagner 1988; Frechen 1990, 1991a).Die stratigraphische Stellung der Löß-/Paläobodenabfolge oberhalb der Mittelterrassenschotter wirdkontrovers diskutiert. Zahlreiche Bearbeitungen liegen vor (Brunnacker et al. 1975; Razi Rad 1976; Bibus 1980; Bosinski et al. 1983; Turner 1986). In neuerer Zeit sind im DEUQUA-Exkursionsführer(Hrsg. W. Schirmer 1990) mehrere Aufsätze erschienen (Turner 1990a u. b; Hentzsch 1990; Haesaerts1990; Frechen 1990; Kolfschoten 1990; v. d. Bogaard u. Schmincke 1990). Dabei wird in der Arbeit vonHaesaerts eine neue stratigraphische Interpretation vorgestellt, die weiter unten diskutiert werden soll.In dieser Arbeit sollen die chronostratigraphischen Ergebnisse im Bezug zur Terrassen- und Lößstratigraphie des Mittel- und Niederrheins unter besonderer Berücksichtigung der TL-Untersuchungen derobersten Parabraunerde diskutiert werden.

Geologischer Überblick

Der Schotterkörper der Kiesgrube Schneider bei Ariendorf wird als mittlere Mittelterrasse aufgrund seiner morphologischen Position angesprochen. Oberhalb der mittleren Mittelterrasse (Kaiser 1961, Bibus1980) oder Leubsdorfer Terrasse im Sinne von Brunnacker et al. (1975) liegt eine bis zu 15 m mächtigeLöß-/Paläobodenabfolge, die durch mehrere Tephren und Paläobodenhorizonte untergliedert werdenkann. Auf der Terrassenoberfläche lagert konkordant eine aus verwittertem Selbergittuff bestehende interglaziale Bodenbildung, das Ariendorfer Interglazial im Sinne von Brunnacker et al. (1975). Die hangenden Deckschichten werden von Brunnacker et al. (1975) vom Liegenden zum Hangenden als Lößdecke 1 bis III beschrieben, die jeweils einen Glazial-/Interglazialzyklus umfassen. Haesaerts (1990)gliedert im Liegenden der Löß-Decke 1 eine weitere Lößdecke aus, die von einer Parabraunerde überprägt sein soll.

26

Die Löß-Decken bestehen jeweils aus sandigen Lössen, Schwemmiössen und Fließerden mit viel Hangschuttmateral. In den Löß-Decken 1 und II sind basaltische Tephren zwischengeschaltet.Die Löß-Decke 1 besteht aus sandigem Löß mit Rinnenfüllungen aus Schwemmlöß. Sie schließt ab miteinem Lößkindl bzw. Cc-Horizont. Darüber lagert ein rötlicher brauner Bv-Horizont.Die Löß-Decke II besteht aus Löß mit Fließerden, stellenweise sind geringmächtige Lagen von basaltischer Tephra aufgetreten. Im unteren Bereich sind überwiegend Sandlösse mit Sandlinsen und eingeschwemmten Lößkindeln vorhanden. Nach oben folgt eine Diskordanz mit einem Lokalschotterband,an das sich viele Schuttschnüre im cm-Bereich anschließen. Autochthone Lößablagerungen liegen unterhalb der Parabraunerde nicht vor. Nach oben hin sind Fließerden mit Schieferbruchstücken undSchottermaterial in Kiesgröße vorhanden. Die Löß-Decke II schließt mit dem Bt-Rest einer Parabraunerde ab. Der Bt-Rest wird von einer Diskordanz gekappt. Darüber lagert eine Schuttschnur aus sandigkiesigem Material und umgelagertem Bodenmaterial sowie eine Humuszone. Zur Zeit der Probennahme war die Humuszone dreigegliedert. Der unterste Bereich ist reich an Bimslapilli (bis zu 2 cm Durchmesser), die mittlere Lage enthält mehr Schuttmaterial und etwas weniger Bimsbrocken. Der obere Bereich enthält nur noch vereinzelt Bimsbruchstücke in cm-Größe und deutlich weniger Schuttmaterial.Die Löß-Decke III besteht aus Fließerden, in denen durchgängig devonisches Schuttmaterial in Kies-größe vorkommt. Die Fließerden sind von zwei schwachen Naßböden untergliedert. Desweiteren kommen Schuttschnüre und geringmächtige Sandlinsen vor. Weitere stratigraphische Einheiten waren zurZeit der Probennahme nicht vorhanden.

Thermolumineszenz-Altersbestimmungen/Datierungsprinzip

Unter Thermolumineszenz versteht man allgemein eine Leuchterscheinung, die neben der Planck‘schenStrahlung beim Erhitzen von nichtleitenden Feststoffen, darunter Minerale wie Quarze, Feldspäte, Zirkone u.a., entsteht. Diese Leuchterscheinung beruht auf der Fähigkeit vieler Minerale, bei Anregungdurch energiereiche Strahlung einen Teil der Anregungsenergie in Form von potentieller Energie zuspeichern. Die energiereiche Strahlung stammt in der Natur aus dem Zerfall radioaktiver Elemente, inder Hauptsache der radioaktiven Isotope der Uran- und Thoriumzerfallsreihen sowie Kalium-40 undder kosmischen Strahlung.Um Sedimente mit Hilfe von Thermolumineszenz physikalisch datieren zu können, müssen einige Voraussetzungen erfüllt sein. Zunächst muß das Sediment während des äolischen Transportes oder währendder Umlagerung durch das Sonnenlicht so lange belichtet worden sein, daß die TL-Uhr vor der Sedimentation bis auf Null oder bis auf den unbleichbaren, aber meßbaren Restbetrag zurückgestellt wird.Die Voraussetzung ist für äolisch abgelagerte Lösse in den meisten Fällen, wie Berger (1990) an rezenten äolisch abgelagerten Sedimenten nachwies, erfüllt. Dies trifft aber nicht unbedingt für solifluidaloder durch Abspülvorgänge umgelagerte Sedimente zu. Die notwendige Dauer der Sonnenlicht-Exposition, um die Korngrößenfraktion 4-11 im bis auf den unbleichbaren Rest zurückzubleichen, beträgtbei der TL zwischen 12 und 16 Stunden. Bei der IRSL reichen bereits 3-5 Minuten um die Lumineszenzauf etwa 5% des Ausgangssignals zu reduzieren. Aufgrund der höheren Sensitivität sind die Optisch Stimulierten Lumineszenz-Methoden besser geeignet, um rasch umgelagerte Sedimente zu datieren (Frechen, Boenigk u. Weidenfeller, 1995).Das Datierungsprinzip beruht auf dem Anwachsen eines Strahlenschadens vom Zeitpunkt der Sedimentation an (Abb. 10). Die im Labor gemessene Lichtintensität ist proportional zur akkumuliertenDosis, das heißt sie ist proportional der Anzahl der Strahlenschäden, die die Minerale im Laufe der Zeitseit der Sedimentation akkumuliert haben. Im Labor werden diese Abläufe mit künstlicher Belichtungund Bestrahlung simuliert. Das Lumineszenz-Alter oder Sedimentationsalter wird aus dem Quotientenvon akkumulierter Dosis (ED) und jährlicher Dosis (AD) berechnet.

27

deposited during an older phase of the Saale Gold Singe. The biostratigraphy of the fauna fromAriendorf 2 does not contradict a Saalian age for this level. The age of Ariendorf 1 is somewhat problematic as this level is not closely stratified to either the Hüttenberg pumice or the dated tephras of theAriendorf Interglacial. Ariendorf 1 is located in the middle of a series of loess-palaeosol units which arcdated to between 410,000 BP and 2 15,000 BP. However, the biostratigraphy of certain of the larger andsmaller mammals from the Ariendorf 1 fauna shows that this level, and presurnably Loess Bed 1, postdate the Holstein Interglacial sensu stricto. (E. T)

STRATIGRAPHIE DES MITTELPLEISTOZÄNPRQFIL5 VON ARIENDORF

AM MITTELRHEIN

(w. BOENIGK M. FRECHEN)

Das von Brunnacker et al. (1975) geologisch untersuchte Pleistozänprofil Ariendorf gilt neben Kärlichund Miesenheim als eines der bedeutendsten Mittelpleistozänprofile des Mittelrheingebietes. In denletzten Jahren sind die Deckschichten der Kiesgrube der Fa. Karl Schneider in Ariendorf Ziel mehrererDatierungsstudien gewesen. Fuhrmann (1983; vgl. Lippolt, Fuhrmann u. Hradetzky 1986) datierte denoberen Selbergittuff mit der konventionellen 40Ar/39Ar-Methode, v. d. Bogaard u. Schmincke (1988) untersuchten die Birnstephren mit der 40Ar/39Ar-Einzelkristall-Methode. Thermolumineszenz-Alter anSedimenten der Löß-/Paläobödenabfolgen wurden in mehreren Arbeiten bestimmt (Balescu 1988; Zöller, Stremme u. Wagner 1988; Frechen 1990, 1991a).Die stratigraphische Stellung der Löß-/Paläobodenabfolge oberhalb der Mittelterrassenschotter wirdkontrovers diskutiert. Zahlreiche Bearbeitungen liegen vor (Brunnacker et al. 1975; Razi Rad 1976; Bibus 1980; Bosinski et al. 1983; Turner 1986). In neuerer Zeit sind im DEUQUA-Exkursionsführer(Hrsg. W. Schirmer 1990) mehrere Aufsätze erschienen (Turner 1990a u. b; Hentzsch 1990; Haesaerts1990; Frechen 1990; Kolfschoten 1990; v. d. Bogaard u. Schmincke 1990). Dabei wird in der Arbeit vonHaesaerts eine neue stratigraphische Interpretation vorgestellt, die weiter unten diskutiert werden soll.In dieser Arbeit sollen die chronostratigraphischen Ergebnisse im Bezug zur Terrassen- und Lößstratigraphie des Mittel- und Niederrheins unter besonderer Berücksichtigung der TL-Untersuchungen derobersten Parabraunerde diskutiert werden.

Geologischer Überblick

Der Schotterkörper der Kiesgrube Schneider bei Ariendorf wird als mittlere Mittelterrasse aufgrund seiner morphologischen Position angesprochen. Oberhalb der mittleren Mittelterrasse (Kaiser 1961, Bibus1980) oder Leubsdorfer Terrasse im Sinne von Brunnacker et al. (1975) liegt eine bis zu 15 m mächtigeLöß-/Paläobodenabfolge, die durch mehrere Tephren und Paläobodenhorizonte untergliedert werdenkann. Auf der Terrassenoberfläche lagert konkordant eine aus verwittertem Selbergittuff bestehende interglaziale Bodenbildung, das Ariendorfer Interglazial im Sinne von Brunnacker et al. (1975). Die hangenden Deckschichten werden von Brunnacker et al. (1975) vom Liegenden zum Hangenden als Lößdecke 1 bis III beschrieben, die jeweils einen Glazial-/Interglazialzyklus umfassen. Haesaerts (1990)gliedert im Liegenden der Löß-Decke 1 eine weitere Lößdecke aus, die von einer Parabraunerde überprägt sein soll.

26

Die Löß-Decken bestehen jeweils aus sandigen Lössen, Schwemmiössen und Fließerden mit viel Hangschuttmateral. In den Löß-Decken 1 und II sind basaltische Tephren zwischengeschaltet.Die Löß-Decke 1 besteht aus sandigem Löß mit Rinnenfüllungen aus Schwemmlöß. Sie schließt ab miteinem Lößkindl bzw. Cc-Horizont. Darüber lagert ein rötlicher brauner Bv-Horizont.Die Löß-Decke II besteht aus Löß mit Fließerden, stellenweise sind geringmächtige Lagen von basaltischer Tephra aufgetreten. Im unteren Bereich sind überwiegend Sandlösse mit Sandlinsen und eingeschwemmten Lößkindeln vorhanden. Nach oben folgt eine Diskordanz mit einem Lokalschotterband,an das sich viele Schuttschnüre im cm-Bereich anschließen. Autochthone Lößablagerungen liegen unterhalb der Parabraunerde nicht vor. Nach oben hin sind Fließerden mit Schieferbruchstücken undSchottermaterial in Kiesgröße vorhanden. Die Löß-Decke II schließt mit dem Bt-Rest einer Parabraunerde ab. Der Bt-Rest wird von einer Diskordanz gekappt. Darüber lagert eine Schuttschnur aus sandigkiesigem Material und umgelagertem Bodenmaterial sowie eine Humuszone. Zur Zeit der Probennahme war die Humuszone dreigegliedert. Der unterste Bereich ist reich an Bimslapilli (bis zu 2 cm Durchmesser), die mittlere Lage enthält mehr Schuttmaterial und etwas weniger Bimsbrocken. Der obere Bereich enthält nur noch vereinzelt Bimsbruchstücke in cm-Größe und deutlich weniger Schuttmaterial.Die Löß-Decke III besteht aus Fließerden, in denen durchgängig devonisches Schuttmaterial in Kies-größe vorkommt. Die Fließerden sind von zwei schwachen Naßböden untergliedert. Desweiteren kommen Schuttschnüre und geringmächtige Sandlinsen vor. Weitere stratigraphische Einheiten waren zurZeit der Probennahme nicht vorhanden.

Thermolumineszenz-Altersbestimmungen/Datierungsprinzip

Unter Thermolumineszenz versteht man allgemein eine Leuchterscheinung, die neben der Planck‘schenStrahlung beim Erhitzen von nichtleitenden Feststoffen, darunter Minerale wie Quarze, Feldspäte, Zirkone u.a., entsteht. Diese Leuchterscheinung beruht auf der Fähigkeit vieler Minerale, bei Anregungdurch energiereiche Strahlung einen Teil der Anregungsenergie in Form von potentieller Energie zuspeichern. Die energiereiche Strahlung stammt in der Natur aus dem Zerfall radioaktiver Elemente, inder Hauptsache der radioaktiven Isotope der Uran- und Thoriumzerfallsreihen sowie Kalium-40 undder kosmischen Strahlung.Um Sedimente mit Hilfe von Thermolumineszenz physikalisch datieren zu können, müssen einige Voraussetzungen erfüllt sein. Zunächst muß das Sediment während des äolischen Transportes oder währendder Umlagerung durch das Sonnenlicht so lange belichtet worden sein, daß die TL-Uhr vor der Sedimentation bis auf Null oder bis auf den unbleichbaren, aber meßbaren Restbetrag zurückgestellt wird.Die Voraussetzung ist für äolisch abgelagerte Lösse in den meisten Fällen, wie Berger (1990) an rezenten äolisch abgelagerten Sedimenten nachwies, erfüllt. Dies trifft aber nicht unbedingt für solifluidaloder durch Abspülvorgänge umgelagerte Sedimente zu. Die notwendige Dauer der Sonnenlicht-Exposition, um die Korngrößenfraktion 4-11 ~um bis auf den unbleichbaren Rest zurückzubleichen, beträgtbei der TL zwischen 12 und 16 Stunden. Bei der IRSL reichen bereits 3-5 Minuten um die Lumineszenzauf etwa 5% des Ausgangssignals zu reduzieren. Aufgrund der höheren Sensitivität sind die Optisch Stimulierten Lumineszenz-Methoden besser geeignet, um rasch umgelagerte Sedimente zu datieren (Frechen, Boenigk u. Weidenfeller, 1995).Das Datierungsprinzip beruht auf dem Anwachsen eines Strahlenschadens vom Zeitpunkt der Sedimentation an (Abb. 10). Die im Labor gemessene Lichtintensität ist proportional zur akkumuliertenDosis, das heißt sie ist proportional der Anzahl der Strahlenschäden, die die Minerale im Laufe der Zeitseit der Sedimentation akkumuliert haben. Im Labor werden diese Abläufe mit künstlicher Belichtungund Bestrahlung simuliert. Das Lumineszenz-Alter oder Sedimentationsalter wird aus dem Quotientenvon akkumulierter Dosis (ED) und jährlicher Dosis (AD) berechnet.

27