1The classical evolutionary approach to morphogenesis, from the perspective of the accumulation of changes at a major scale – implicitly from the temporal point of view – gives changes occurred in the Holocene marginal importance. These processes and phenomena are considered to be "minor", while the physical attribute "superficial" has often been extrapolated, into a logical and deductive point of view, according to the infinitesimal duration of this interval as compared to the previous geological periods, considerably longer.
2The idealised perception upon evolution, through cumulative, gradual changes, is also to be found even in the consecrated division into periods of the Holocene. The increase of paleoenvironmental research from the last decades and the results obtained have allowed for a completion of the classical model elaborated by A. BLYTT (1881) and R. SERNANDER (1908) with numerous informations about the spatial and temporal variability of climatic conditions and implicitly of hydrical, biogeographical and soils characteristics defining for the Holocene paleogeomorphological environments.
3There are at least two elements with particular significance (from the point of view of our research):
The fact that beginning with approximately 7000 BP (at least) to 4000-5000 BP, a global "optimal period" in which the climate was essentially similar to the present one was registered (R. RAIKES, 1967; R. NEIL, 1989). It is significant that, though lacking arguments to sustain this point of view and through the excessive generalisation of the warm and wet characteristic attributed to the Atlantic period, the reconstruction of paleoenvironments in Romania has provided for deductive "clichés", insufficiently founded (exclusively palynologic ones) such as: the generalisation of the forest vegetation in the Transylvanian Plain and the high sector of the Western Plain, the presupposition of an intense fluvial morphodynamic with massive sedimentation, etc.
The fact that during the Holocene, in temperate Europe (and not only) there have been at least three periods of abrupt deterioration of the climate, (called by P. ROGNON, 1983, "climatic crises"; quoted by R. NEIL, 1989) followed by a return to the previous states during only a few centuries.
4Starting from these facts, we have tried to outline possible defining states from the Holocene evolution of the low plain of the Crisuri (Fig. 1) by correlating the following informational sources:
Buried soils whose environmental significance could be extrapolated temporally owing to their "supporting" quality for several material cultures, and whose age and allegiance have been accurately determined by the archaeological research (especially those of S. DUMITRASCU, 1968; I. BERINDEI and S. DUMITRASCU, 1969; I. CRISAN, 1992, 1993).
The positional relations of archaeological sites with the present-day morphology.
The results of paleobotanic and especially paleozoological on-going researches (T. JURCSÁK, 1970).
Representative profiles of fossil soils, analysed by recent studies regarding the Holocene evolution of the landscape of the Transylvanian Plain (F. PENDEA et al., 2004).
Important recent studies regarding paleoenvironmental reconstruction of the superior Holocene from Central Europe (M. MEYER, 1997; H. RITTWEGER et al., 2000; R. URZ et al., 2002).
Figure 1 - Location of the study area.
5Following the spatial distribution of archaeological sites in the Crisuri Plain, we notice in the first place a considerable frequency of those bearing remains (transitional Neolithic, early Bronze Age, Iron Age, the Roman period), some of which attest successive cultures going on up to the Middle Age and even up to the present (Fig. 2).
Figure 2 - Location of the archaeological sites.
1: Low alluvial plain (subsidence area). 2: Middle plain of low pediments. 3: Upper plain of high pediments and alluvial terraces. 4: piedmont hills. 5: lakes. 6: localities. 7: archaeological site. EBA: Early Bronze Age. IA: Iron Age. RP: Roman Period. EMA: Early Middle Age. MA: Middle Age.
6The localisation of the sites from the area between the Crisul Repede and Crisul Negru rivers is eloquent as these are disposed along a line that follows from north to south the last prolongation to the west of some higher, well-individualised river meadows (precisely indicated by the 110 m level curve), which in fact indicates an older interference strip between the eastern, higher plain of Pleistocene terraces, consistently extended to the west through lengthy pediments and the subsidence plain formed in the sinking area of the faulted cristalline underlying substratum.
7It is assumed that this interference area has entered from a multitude of reasons in the use of Neolithic farmers (who, around 7000-7500 BP, came from the Close East, followed the Danube-Rhine axis and reached the Lower Danube basin and then the Pannonic Plain) especially due to the relative stability of the rivers' network, the plainness of higher surfaces, guarded against floods and the complementarity of resources. The alluvial soils exploited in agriculture and the forest resources of the nearby hilly region, on the one hand, and, on the other hand, the large expanses of water which allowed for the breeding of cattle and pigs, the only species that were domesticated by the savage predecessors (who had replaced the herds of sheep and goats) with no strict spatial dependence determined by cultivated lands or shelters.
8The material vestiges of the Neolithic cultures offer valuable and reliable information, implicitly on the paleoenvironmental conditions of morphogenesis. Among the various archaeological sites studied in the Crisurilor Plain, the most valuable in establishing the climatic framework and the subsequent conditions are those from Girisu de Cris, Salca, Rapa (close to Tinca), Cefa, etc. (Fig. 2).
9It has been studied in three almost identical sections (morphologically and through the artefactual content of the profile) by S. DUMITRASCU (1968). Situated 16 km west from Oradea, nearby the homonym village, within the right side bank of the Crisul Repede alluvial channel, the profile opened to a depth of 1.5 m proves the existence of a stratum of culture "Basarabi" (Hallstatt-C, 600-800 BP) of 30-40 cm under the present vegetal layer, beneath which there is a layer of yellow, alluvial soil (40-50 cm) containing fine sand and which, at its turn, covers a horizon of black, cernoziomic soil (20-40 cm) in which ceramic fragments of the Cotofeni culture (Early Bronze Age) have been discovered (Fig. 3). Under the latter, there is the parental material made up of yellow sandy clays.
Figure 3 - Section in the right side bank of the Crisul Repede River at Girisu de Cris village proximity.
1: topsoil. 2: sandy black soil and cultural layer (Hallstatt-Bassarabi culture). 3: alluvial infill. 4: cultural layer in BFS horizon (Late Neolithic – Early Bronze Age). 5: alluvial layer. 6: hearth remains (ash).
10The presence of the black soil "bearer" of the Cotofeni culture, synchronous with those from Pecel-Hungary and Baden-Retz, Germany, dated to 3200-3500 BP (through comparative archaeological analyse of the ceramic fragments features consisting mainly in shapes, incisions, prods and ornaments, certified later by radiocarbon estimation; (Photo 1) is exceptionally relevant. It is more than probably, of the same pedologic sequence, specific for the stratigraphy of river meadows from Central Europe that was discovered and described for the first time in South Germany by H. RITTWEGER (2000) under the name of "Black Floodplain Soil" (BFS). This type of soil was formed in the Boreal–Atlantic interval and achieved its final characteristics only during the Sub boreal period when the appearance of illuvial processes in the river meadows was possible, given the drier climate accompanied by a decrease in the phreatic level. Therefore, BFS is a gleic cernoziome (other typological variations are also noted) buried by alluvial, prolluvial and colluvial deposits. The moment of its surface evolution cessation and fossilisation (burial) has been differently recorded in literature, from the Early Bronze Age (between 3235±55 and 3160±155 BP – M. MEYER, 1997) to the middle of the first millennium (H. RITTWEGER, 2000), which is absolutely reasonable taking into account the possible regional territorial differences of the process.
Photo 1 - Ceramic fragments (Cotofeni culture, Late Neolithic - Early Bronze Age, 3200-3500 BP) discovered in Girisu de Cris site (source: I. BERINDEI and S. DUMITRASCU, 1969).
11In the present situation, the estimation of M. MEYER (1997) frames temporally, almost rigorously, the presence of the Cotofeni culture at the level of this BFS horizon and it is obvious that fossilisation took place much earlier than the half of the first millennium since, at that time, the horizon of Basarabi culture was already outlined (VIIIth - VIth centuries BP), even if it was nevertheless separated by the previous cultural level by a clay-sandy alluvial horizon of approximately 40-50 cm thick.
12But for the present purpose, a far greater relevance than rigorously establishing the moment of fossilisation is the interpretation of the presence of this BFS horizon from a morphogenetic point of view. This is clearly connected with the Atlantic - Sub boreal “climatic optimum” which was felt in the western part of Romania until about 3000 BP, affirmation proved by the presence of the Cotofeni culture (Early Bronze Age), whose subsequent burial marks the decline of the relatively “quiet” morphogenetic period with which it corresponded.
13The Cotofeni level of habitation was possible because of the decrease in the phreatic level, of the deepening of the water “thread” and because of the individualisation of high river meadows, relatively stabilised from a morphodynamic point of view.
14These transformations also indicate the fact that, climatically speaking, the Atlantic period was, at least during its last phase, less wet than it is usually considered in the majority of the previous studies on the Holocene climatic framework of Eastern Europe.
15This fact is also indicated by the researches of T. JURCSÁK (1970) on domestic remains from the Neolithic settlement of Salca. The reconstruction of the fauna from this site situated at the level of the first terrace of the Crisul Repede (which was then outlined through the deepening and withdrawal of the river) has highlighted, besides forest species, the presence of steppe elements: Bos primigenius Boj (frequently), Equus hemionus, Equus cabalus and Otis tarda, elements that indicate for the second part of the Atlantic period and, of course, for the Sub boreal, a pretty obvious dryness/aridity.
16The favourability of the paleoenvironmental conditions is also indicated by the considerably larger number of sites attesting transitional Neolithic cultures and those of Early Bronze Age in terms of successive material cultures. The fact that part of them are to be found in the western part of the alluvial plain (west from the line Girisu de Cris-Cefa-Inand) where, even in the present, the phreatic level is at only 1-2 m deep, while the supraphreatic horizon and the marshy areas occupy considerable surfaces, is also very eloquent.
17The Cotofeni level was covered by the alluvial layer developed as a result of the climatic deterioration that occurred with the passage to the Sub Atlantic period and which was obviously more intense in its first part (up to about 1400-1000 BP), taking into account that in the last millenium BP a new warm and relatively dry period settled in. The last mentioned one emphasized another cycle of morphodynamic stability (westward within the subsidence area) and of steppe eastward spreading. These changes determined a second "wave" of significant inhabitation attested by the large number of Hallstattiene settlements, among which the Girisu de Cris site is also included with its above mentioned Basarabi cultural horizon.
18Their presence (VIInd - VIth centuries BP) indicates a new phase of relative environmental stability during the first half of the last millennium BP, whose duration was considerably shorter.
19There are a number of clues indicating the existence of several “pulse”/phases of climatic deterioration whose effects differed slightly at the territorial level and which were closely connected with the local geomorphological circumstances and with the regional tendencies of neotectonic processes. Thus, if in the Girisu and Santandrei sites the horizon of Hallstatt culture C is to be found immediately underneath the present day bio-accumulation horizon and it was preserved undisturbed as a result of the re-deepening of the Crisu Repede river (which at present is only a little bit lower than the BFS horizon), in the areas site (also Hallstatt), situated further west, the same horizon is covered by an alluvial horizon of about 80 cm. This leads to the conclusion of the existence of a short climatic deterioration (cold-damp/wet) in the time interval separating the Hallstatt and Latene cultures (VIth BP - Ist AD centuries). Certainly enough, this fact needs be proved by other indications and arguments as well.
20The configuration of the profile from Râpa is also significant in this respect. The site is situated close to the Râpa settlement (near Tinca), in the river meadow of the Crisul Negru, at the contact area between the pediments and the alluvial plain. It has been described by I. BERINDEI and S. DUMITRASCU (1969) and interpreted from a genetic evolutive perspective on the Crisuri Plain and of the river meadows from the gulf depressions. Although the above authors relate the differences in the profile with hypothetical tectonic-climatic circumstances, which are difficult to demonstrate and even improbable in certain aspects, the paleoenvironmental value of their research is indisputable. This value is conferred by the existence of a lower alluvial horizon (which corresponds with the present alluvial bad of the Crisul Negru river) made up of sands, clays and coarse gravels which include numerous remains of tree of different sizes (Fig. 4). It is, undoubtedly, the result equivalent of a "climatic crisis" (can this be, by any means, synchronous with the one that fossilised the BFS horizon, bearer of transitional Neolithic and early Bronze cultures?) but its age can only be determined through modern dating techniques. The length of the respective period was considerable taking into account the fact that, above the horizon with trunks/stumps – which is continued on an undetermined thickness – there is a clay-sandy horizon (which only indicates the mitigation of the intensity of the denudational processes) with thickness of about 100 cm.
Figure 4 - Section in the right-side bank of the Crisul Negru River near Rapa village.
1: topsoil. 2: sandy-alluvial infill. 3: La Tène cultural layer (sandy black soil with ash and charcoal remains, artefacts, gravel and animal bones). 4: sandy-clay alluvial infill. 5: alluvial gravel with tree-trunk deposition.
21Above the latter there is a horizon of material culture, dark-grey, 30 cm in thickness (which goes down to 2.60 m deep) which has been attributed, based on ceramic remains mostly, to the second age of the Iron Age-Latene (IInd - IVth centuries AD, the Daco-Roman period – Photo 2). This indicates the fact that at the beginning of the first millennium the region recorded a warmer and dryer climate, reflected by a diminished fluvial erosion (in higher areas) and accumulation processes in river meadows, as well as by the decrease of river flows, the deepening of rivers, the descent of the phreatic level and implicitly by the existence of the pedogenetic medium presupposed for the genesis of the river meadow soil. Eolian reworking of river sediments can be recorded on the higher stands of the floodplain. After this (apparently) relatively short period of stability, in the IInd - Vth centuries AD, there followed a new period of environmental decline which determined the burying of the "Daco-Roman" soil under a clay-sandy deposit, about 170 cm thick.
Photo 2 - Ceramic fragments (La Tène culture, Iron Age, Daco-Roman period, 200-400 AD) discovered in Râpa–Tinca site (source: I. BERINDEI and S. DUMITRASCU, 1969).
22It is to be noticed that, from a temporal and phenomenological point of view, these obvious mutations of the paleoenvironmental states, specific for the Eastern extremity of the Pannonic Basin, are surprisingly closely correlating with the geochronology elaborated for the basin of the Lahn river (Germany) by R. URZ et al. (2002).
23Taking into account the presented arguments, we consider that these elements, which must undoubtedly be studied thoroughly on quantitative bases (micro-morphological and sedimentological analyses, absolute datings, etc.), can constitute useful starting points towards the edification of a more realistic vision regarding climatic mutations in the Middle and Upper Holocene in western Romania. This is indispensable to objectively integrate the knowledge of the recent past in order to be able to anticipate essential changes that might occur in the future, on a short and medium term.
24One of the components of this new point of view is the reassessment of the importance ussually given to the tectonic factor in morphogenesis. It challenges the idea of numerous regional studies which attribute important evolution changes almost exclusively to tectonic factors, to the effects of local subsidence and raisings based on the existence of the crystalline foundation which is highly faulted, rectangular, in blocks unevenly sunk and differentiated through the direction of their movement.
25The role of the neo-tectonic factors in the regional differentiation of certain processes cannot be contested, but we consider it an important fact that even at the level of relatively short time periods (geologically speaking) such as the Holocene, there are enough evidences and arguments to support the existence of an appreciable number of climatic variations during short temporal sequences. As a result, it is implicit that in interpreting the paleoenvironment (especially that of the mid and upper Holocene), the climatic factor is by far more important than the tectonic one. Furthermore, the profound understanding of the effects it has generated (hydric, geomorphic, cultural, etc.) and their correlation in explanatory integrated models, would allow for an even more objective evaluation of the role recent tectonics has had in the evolution of Holocene paleoenvironments.
Acknowledgements: We would like to thank the Crisurilor Land Museum from Oradea for their most professional assistance concerning the archaeological sites and artefact assignment. Some of the fieldwork has been funded by the CNCSIS grant no 133/2004 “Natural Potential, Ressources and Territorial Planning in the Mining Impact Area of the Ignis, Gutai and Varatec Mountains”, director: Dan PETREA.