the cryptotephra record of the marine isotope stage 12 to 10 interval 460 335 ka at tenaghi philippon greece exploring chronological markers for the middle pleistocene of the mediterranean region abstract precise chronologies that allow direct correlation of paleoclimate archives are a prerequisite for deciphering the spatiotemporal characteristics of short term climate variability such chronologies can be established through the analysis of tephra layers that are preserved in the respective sedimentary archives here we explore the yet untapped tephrochronological potential of the eastern mediterranean region for the middle pleistocene specifically for the interval spanning marine isotope stages mis 12 10 460 335 ka high resolution cryptotephra analysis was carried out on peat cores spanning the mis 12 10 interval that have been recovered from the iconic climate archive of tenaghi philippon ne greece eighteen primary cryptotephras were identified and major and trace element analyses of single glass shards from all cryptotephras were performed in order to correlate them with their eruptive sources the results suggest origins from both italian and aegean arc volcanoes specifically one cryptotephra layer could be firmly correlated with the cape therma 1 eruption from santorini which makes it the first distal tephra finding for this eruptive event while eight further cryptotephras could be tentatively correlated with their volcanic or even eruptive sources the provenance of another nine cryptotephras as yet remains unknown the relatively large number of cryptotephras that could not be assigned to specific volcanic sources and eruptive events reflects the still considerable knowledge gap regarding the geochronology and geochemistry of proximal tephra deposits from the middle pleistocene of the central and eastern mediterranean regions due to the lack of well dated middle pleistocene eruptions we provide age estimates for all cryptotephra layers identified in the mis 12 10 interval at tenaghi philippon based on high resolution pollen data from the same cores while eight of the identified cryptotephras were deposited within mis 12 438 427 ka one cryptotephra was deposited at the onset of mis 11 419 ka five cryptotephras during the younger part of mis 11 391 367 ka and four cryptotephras during mis 10 359 336 ka the high number of cryptotephras from multiple sources as recorded in the mis 12 10 interval at tenaghi philippon highlights the key role of this archive for linking tephrostratigraphic lattices for the middle pleistocene of the central and eastern mediterranean regions

quaternary fluvial volcanic stratigraphy and geochronology of the capitoline hill in rome in and around rome coastal and fluvial sediments influenced by quaternary sea level changes interfinger with accurately datable highly potassic pyroclastic volcanic units we describe the complex internal geology of the capitoline hill for centuries a place of leading importance in ancient rome and more recently a focus of archaeological research outcrops and many new drill cores reveal at least four cycles of valley cutting and filling probably recording the history of the tiber river in response to changes in sea level single crystal 40 ar 39 ar dates on sanidine give ages of 518 6 413 5 and 353 2 ka for three prominent volcanic units filling separate paleovalleys the roman region offers the potential for direct age calibration of the quaternary sea level record

structure and evolution of the sacrofano baccano caldera sabatini volcanic complex rome abstract sacrofano eruptive center in the eastern part of the sabatini volcanic complex was active between 0 5 and 0 09 m y ago the baccano geothermal area lies at the western edge of sacrofano caldera sedimentary substrata that form the reservoir for this geothermal system were exposed at the surface at the beginning of volcanic activity the volcanic history of the sacrofano center can be divided into three stages 1 1 construction of the sacrofano pyroclastic edifice by predominantly strombolian activity 2 2 collapse of sacrofano caldera following eruption of pyroclastic flows 3 3 development of the baccano explosive center at the western edge of sacrofano caldera and collapse of baccano caldera hydrovolcanic activity that began at the end of the first stage of sacrofano can be explained by a drop in the magma level in the conduit that relieved hydrostatic pressure in the aquifer as intense fracturing associated with caldera collapse penetrated the carbonate reservoir the entrapped water flowed towards the conduit to balance the pressure change the close link between tectonism and volcanism in the sacrofano center suggests that eruptions there may have been triggered by gravity faults related to regional tectonics

revisiting kokkinopilos middle pleistocene radiometric dates for stratified archaeological remains in greece the red bed site of kokkinopilos is an emblematic and yet also most enigmatic open air palaeolithic site in greece stimulating controversy ever since its discovery in 1962 while early research raised claims for stratigraphically in situ artifacts later scholars considered the material reworked and of low archaeological value a theory that was soon to be challenged again by the discovery of in situ lithics including handaxes here we present results of a latest and long term research that includes geoarchaeological assessments geomorphological mapping and luminescence dating we show that the site preserves an overall undisturbed sedimentary sequence related to an ephemeral lake marked by palaeosols and stratigraphic units with palaeolithic material that is geologically in situ and hence datable our study resolves the issues that have been the source of controversy the depositional environment stratigraphic integrity chronological placement and archaeological potential of the site moreover the minimum ages obtained through luminescence dating demonstrate that the lithic component with bifacial specimens considerably pre dates the last interglacial and therefore comprises the earliest stratigraphically defined and radiometrically assessed archaeological material in greece kokkinopilos has served as a reference site for the interpretation of all other red bed sites in north west greece therefore our results have significantly wider implications by analogy to kokkinopilos the open air sites of epirus should not anymore be considered by default as inscrutable palimpsests with limited archaeological potential rather these sites can be excavated and chronologically constrained this realization opens up new prospects for future research in epirus an area that is the most prolific in palaeolithic remains in greece

an extremely large magnitude eruption close to the plio pleistocene boundary reconstruction of eruptive style and history of the ebisutoge fukuda tephra central japan abstract an extremely large magnitude eruption of the ebisutoge fukuda tephra close to the plio pleistocene boundary central japan spread volcanic materials widely more than 290 000 km2 reaching more than 300 km from the probable source characteristics of the distal air fall ash 150 km away from the vent and proximal pyroclastic deposits are clarified to constrain the eruptive style history and magnitude of the ebisutoge fukuda eruption eruptive history had five phases phase 1 is phreatoplinian eruption producing 105 km3 of volcanic materials phases 2 and 3 are plinian eruption and transition to pyroclastic flow plinian activity also occurred in phase 4 which ejected conspicuous obsidian fragments to the distal locations in phase 5 collapse of eruption column triggered by phase 4 generated large pyroclastic flow in all directions and resulted in more than 250 350 km3 of deposits thus the total volume of this tephra amounts over 380 490 km3 this indicates that the volcanic explosivity index vei of the ebisutoge fukuda tephra is greater than 7 the huge thickness of reworked volcaniclastic deposits overlying the fall units also attests to the tremendous volume of eruptive materials of this tephra numerous ancient tephra layers with large volume have been reported worldwide but sources and eruptive history are often unknown and difficult to determine comparison of distal air fall ashes with proximal pyroclastic deposits revealed eruption style history and magnitude of the ebisutoge fukuda tephra hence recognition of the ebisutoge fukuda tephra is useful for understanding the volcanic activity during the pliocene to pleistocene is important as a boundary marker bed and can be used to interpret the global environmental and climatic impact of large magnitude eruptions in the past

late pliocene volcaniclastic products from southern apennines distal witness of early explosive volcanism in the central tyrrhenian sea two volcaniclastic successions intercalated in pliocene basinal clays from the southern apennines have been analysed to determine their provenance and their relationship with the geodynamic evolution of the western mediterranean the studied deposits are exclusively made up of ashy pyroclasts dominated by fresh acidic to intermediate glass mostly in the form of shards pumice fragments and groundmass fragments with vitrophyric texture crystals include pl opx cpx hbl and rare bt sedimentological features suggest that the volcanic material accumulated near the basin margin by primary fallout processes and was later remobilized by density currents 40 ar 39 ar geochronology allowed dating of one succession at 2 24 0 06 ma corresponding to the late pliocene composition of the volcaniclastic material is typical of a transitional high k calc alkaline series the age and chemical composition constrain the provenance of the volcaniclastic rocks from the southern tyrrhenian domain here volcanic centres were active during pliocene time approximately at the northern end of a volcanic arc formed before the opening of the southernmost part of the sea this paper shows that a detailed study of volcaniclastic products from the southern apennines and calabria can be very useful in collecting new pieces of information on the eruption history of the southern tyrrhenian domain since they record additional data not available from the study of exposed volcanic edifices

computer simulation of transport and deposition of the campanian y 5 ash analyses of grain size and modal composition of the campanian tuff ash layer y 5 from 11 deep sea cores have been carried out this layer represents ash fall that has been correlated with the 38 000 y b p campanian ignimbrite thunell et al 1979 a deposit formed by the largest eruption documented in the mediterranean region during the late pleistocene barberi et al 1978 the bulk deposit is bimodal in grain size and dominated by glass shards the calculated mean grain size of the coarse mode of the individual size distributions decreases with distance from the source and progressively approaches a near constant fine mode of approximately 13 microns distal samples are unimodal in grain size these data combined with a set of vertical profiles of wind 10 year average have been used as input to a computer model that simulates fallout of tephra modelling indicates that the downwind variation of grain size of the coarse mode can be accurately reproduced with transport of ash between 5 and 35 km the observed fine mode of the deposit cannot however be generated by transport of ash as individual particles at these elevations such transport would result in deposition of virtually all of the fine ash beyond the studied area deposition of fine ash within the studied distance of 1600 km from source can only occur by fallout as particle aggregates from a high eruption plume or as individual particles from co ignimbrite ash clouds with a maximum elevation of 3 km the large volume of ash in the fine mode 70 wt and the irregularity in azimuth of low level winds argue against major low level transport of co ignimbrite ash rather the ash may have been derived from both a plinian eruption column and high altitude clouds of co ignimbrite ash with settling of fine ash as particle aggregates

glass chemistry in volcaniclastic sediments of odp leg 107 site 650 sedimentary sequence provenance and chronological implications abstract a detailed chemical investigation of volcanic glass fragments from volcaniclastic strata 6 tephras 1 volcanic debris flow 12 volcanic turbidites of odp leg 107 site 650 sedimentary sequence leads to a varied pattern in terms of both provenance and age constraints the six analyzed tephra strata indicate a provenance from at least three different volcanic provinces aeolian campanian and sicilian channel pantelleria island the older tephra strata 021 018 012 have a large amount of orogenic rhyodacite rhyolite deposits that may be attributed to the aeolian province although no subaerial coeval volcanic activity of similar composition has so far been documented in the aeolian arc tephra 007 is related to the pantelleria island activity and particularly to an ignimbrite episode dated circa 130 ka tephra strata 005 and 003 have a clear campanian provenance and are correlated with analogous tephra layers observed in the tyrrhenian and ionian seas dated circa 107 and 60 ka respectively in the oldest portion of the sequence from 1 3 to 0 13 ma the volcaniclastic sediments were only derived from the aeolian domain whereas in the latest 130 ka the campanian influx becomes much more predominant therefore a general k enrichment trend is observed in the temporal sequence of all the analyzed samples almost 700 point analyses which may be related both to a variation in the source area and to the specific pleistocene magmatic evolution of the peri tyrrhenian volcanic provinces

40 ar 39 ar ages and stratigraphy of the latera caldera italy the latera caldera is a well exposed volcano where more than 8 km3 of mafic silica undersaturated potassic lavas scoria and felsic ignimbrites were emplaced between 380 and 150 ka isotopic ages obtained by 40ar 39ar analysis of single sanidine crystals indicate at least four periods of explosive eruptions from the caldera the initial period of caldera eruptions began at 232 ka with emplacement of trachytic pumice fallout and ignimbrite they were closely followed by eruption of evolved phonolitic magma after roughly 25 ky several phonolitic ignimbrites were deposited and they were followed by phreatomagmatic eruptions that produced trachytic ignimbrites and several smaller ash flow units at 191 ka compositionally zoned magma then erupted from the northern caldera rim to produce widespread phonolitic tuffs tephriphonolitic spatter and scoria bearing ignimbrites after 40 ky of mafic surge deposit and scoria cone development around the caldera rim a compositionally zoned pumice sequence was emplaced around a vent immediately northwest of the latera caldera this activity marks the end of large scale explosive eruptions from the latera volcano at 156 ka

passage of intraseasonal waves in the subsurface oceans 1 this study exploits the coverage of argo array for real time geostrophic oceanography float data sets towards identifying passage of intraseasonal waves over the subsurface global oceans argo a new observing system has provided an unprecedented data coverage and impact the assimilation of argo data reveals that the subsurface ocean temperature carry signatures on the passage of the intraseasonal waves this vast oceanic data sets provided an opportunity to explore the usefulness of coupled assimilation for seasonal forecasts on the passage of these waves the results suggest that the inclusion of subsurface argo profiler data sets can be useful for prediction of the intraseasonal waves in the atmosphere oceans these improved forecasts hold the promise for improved seasonal outlook projections for the dry and wet spells of the monsoon we also demonstrate improved phase relationship on the passage of zonal wind anomalies of the intraseasonal waves and the monsoon rainfall

tephra from the minoan eruption of santorini in sediments of the black sea the explosive eruption of santorini volcano in the aegean sea about 3 300 years ago is of considerable archaeological and volcanological significance1 5 here we report the discovery of tephra from this minoan event in laminated sediments of the black sea this finding provides constraints on the distribution of debris from the eruption we estimate a minimum fallout area of 2 l06 km2 extending from the black sea in the north to the southeastern mediterranean sea the main dispersal axis trends through southern turkey in agreement with other studies of minoan tephra6 7 the tephra deposits should provide a useful reference horizon for assessing the chronology of black sea sediments which has been much debated8 15

hydrological aspects of geophysical borehole measurements in crystalline rocks of the black forest abstract one of six wells drilled into the crystalline rock of the black forest basement during the german continental deep drilling project ktb site survey has been used to detect hydraulically active fractures and to identify their character by a variety of logging tools such as caliper and televiewer logging vertical seismic profiling vsp and electrical and thermal measurements in addition to standard logging recordings in the 265 m moosengrund well drilled into the triberg granite body these methods were applied successfully to discriminate between fractures and breakouts and to identify open and closed fractures and water consuming or water expelling fractures respectively fracture strike dip and width were determined from televiewer data vsp measurements were used to determine the seismic velocities in the unfractured rock and the fracture zones estimates of permeability 10 55 darcy and transmissivity 0 1 1 0cm 2 s 1 of the fracture zones were obtained by the analysis of p waves and tube waves in the vsp records the summed values of the transmissivity yield an upper estimate of the overall transmissivity determined by a pumping test

correlation of a tephra layer in western greece with a late pleistocene eruption in the campanian province of italy abstract the kalodiki fen is a 2 km 2 mire in a small basin within a tectonic depression in epirus western greece since the last glaciation the basin has been occupied by a freshwater lake and has accumulated as much as 9 m of peat which continues to form today a 10 cm thick light brown to olive fine sandy layer appears in cores at depths ranging from 2 9 to 5 7 m the sand fraction of this layer consists mostly of pumice fragments and brown and colorless glass shards with similar major element compositions and it also contains crystal fragments of feldspars mainly sanidine ferromagnesian minerals and probably sphene and apatite the colorless glass has an index of refraction 1 519 0 002 a sample of the overlying peat layer gave a minimum radiocarbon age of about 31 800 1200 yr b p for the deposition of the tephra the likely age of the tephra its index of refraction and its mineralogical and chemical characteristics display strong similarities to tephra from the campanian province of italy mineralogically similar tephra layers have also been reported from a peat deposit at philippi in northeastern greece

the phlegraean fields structural evolution volcanic history and eruptive mechanisms abstract the main event within the volcanic history of the phlegraean fields was the eruption about 35 000 years ago of a huge alkali trachytic ignimbrite 80 km 3 dre followed by caldera collapse the pre caldera activity evidence from geothermal wells and surface outcrops changed from submarine to subaerial shortly before the ignimbrite eruption the caldera was subsequently invaded by the sea and became progressively filled with tuffites and subordinate submarine flows in its northern half the last submarine explosive activity dates back to 12000 10500 yr with the eruption of mostly hydroplinian yellow tuffs recent mostly subaerial activity consists of a series of explosive eruptions whose volume decreases with time until the last eruption of mt nuovo in 1538 a d two peaks in recent activity occur at 10000 8000 and 4700 3000 years ago during post caldera activity eruptive vents migrated from the caldera rim toward the center where there are two distinct zones of recent vents minor collapses occurred within the caldera after the main eruptions often they are eccentric to the vent and displaced toward the caldera center phlegraean explosive activity is characterized by water magma interaction eruptive events without a hydromagmatic component are extremely rare in most cases the evolved trachytic magmas interacted with surface water either the sea or intracaldera lakes however there is evidence of interaction of magma with deep seated aquifers for some plinian events explosivity i e the efficiency of the transformation of thermal into kinetic energy during magma water interaction is largely controlled by the primary fragmentation of the magmatic melt

aeolian dust transport and deposition over crete and adjacent parts of the mediterranean sea monitoring of dust deposition at several stations on crete over a three year period has shown that the present day depositional flux is of the order of 10 100 gm 2 yr 1 most of the dust deposition takes place during a few annual dust events which typically last for 1 3 days dust haze episodes are usually associated with southerly or southwesterly winds which transport fine sediment from north africa dust is raised by a wide variety of meteorological conditions which generate strong near surface winds in the source areas but major long range transport events are often associated with cold fronts linked to the passage of deep mid latitude depressions during winter and spring dust haze frequency and deposition rates are highest in western crete and decrease towards the east suggesting that transport from tunisia and neighbouring parts of north africa is particularly important the measured rate of dust deposition is well below the minimum level required for loess formation deposits which have previously been identified as loess are shown to be uncemented marine marls of tertiary age laboratory analysis of red soils surface sediments and bedrock samples has confirmed that many of the soils contain an important aeolian dust component but it is concluded that a more important source of soil parent material is provided by weathering of local rocks many of the soils contain significant amounts of quartz sand which cannot have been transported across the sea from north africa reworking of weathered material and deposited dust is extensive and is accomplished by both aeolian and fluvial processes tectonically controlled depressions in the mountains and parts of the coastal lowlands have acted as long term sinks in which a thickness of several metres of sediment and soil has accumulated during the quaternary

dimensions and dynamics of co ignimbrite eruption columns very powerful volcanic eruptions cannot always form classical plinian eruption columns1 4 instead collapsing fountains may develop above the vent and shed pyroclastic flows which spread laterally along the ground5 the upper part of these hot dense pyroclastic flows may become buoyant through the entrainment heating and expansion of ambient air coupled with the sedimentation of larger clasts suspended in the flow the buoyant material may rise in a co ignimbrite eruption column carrying massive quantities of fine dust and volatiles into the stratosphere6 7 here we present a model of this process and show that the co ignimbrite columns associated with the eruptions of toba8 9 75 000 years ago and tambora10 in 1815 may have ascended only about 32 and 23 km the latter is comparable with the less powerful 1982 plinian eruption column of el chichon11 this corroborates arguments that the mass of sulphuric acid aerosols injected into the stratosphere and not the eruptive power determines the climatic impact of an eruption12 13

petrogenesis and tectonic setting of the roman volcanic province italy abstract the volcanism in the roman province of italy can be modelled by the partial melting of heterogeneously enriched mantle sources the heterogeneity was created by materials derived from a subducted slab which can still be traced geophysically beneath the central apennines new petrographical and chemical data are presented for the high k calc alkaline and the shoshonitic volcanics of the campania region primary magmas are present only locally the existence of spatial zonation in the volcanism of campania is documented for the first time the shoshonitic leucite basanitic and leucititic volcanics of the phlegraean fields procida ischia and the somma vesuvius areas are at similar degrees of evolution about two times richer in nb and ba than those of northwestern campania and the latium part of the roman province accordingly distinct north western and south eastern subprovinces can be defined the evaluation of enrichment factors that is the abundance ratio between the average contents of each element in the relatively primitive lavas of the low k and the high k suites shows that the mantle sources prior to k metasomatism were different in the two sub provinces of the roman province in the north western one they resembled the sources of ocean island tholeiites and moderately enriched mor basalts in the south east they were similar to those of ocean island alkaline lavas and enriched morb s modelling based on k p ce sr rb ba th sm eu gd y nb and 87 sr 86 sr was carried out it indicates that the range of mantle sources of the volcanics in northwestern campania and latium can be modelled by the addition of 3 to 20 of materials derived by partial melting of carbonaceous pelites to a sr enriched mantle wedge comparable to the honolulu mantle source least enriched in nb the production of sr enriched mantle wedge requires either the action of fluids produced by dehydration of subducted oceanic crust or a small amount of metasomatism caused by the presence of carbonatite melts the near absence of ti ta nb yb and the highly fractionated ree in the metasomatizing component requires the presence of residual garnet and accessory ti rich minerals during the partial melting of the subducted sediments the writers propose that the mantle wedge overlying the subducted slab was hybridized by melts produced by partial fusion of subducted material derived from the continental crust probably sediments this process played a dominant role in the generation of the mantle sources from which the high k calc alkaline shoshonitic leucite basanitic and leucititic magmas of the roman province were derived

the pianico tephra an early middle pleistocene record of intraplate volcanism in the mediterranean distal tephra are a valuable record of the volcano tectonic evolution of an area under study here we document the case of the early middle pleistocene rhyolitic tephra of pianico discovered in the southern italian alps the geochemical characteristics of pianico are unique among the distal tephra outcropping in italy and indicate an intraplate volcanism at the source the alkali composition and trace elements show a striking resemblance with the rhyolitic complex of the euganean hills located 170 km from pianico however these rhyolites are much older oligocene alternatively the source of this intraplate volcanic episode could be located in the southern tyrrhenian sea

revised tuning of ocean drilling program site 964 and kc01b mediterranean and implications for the δ18o tephra calcareous nannofossil and geomagnetic reversal chronologies of the past 1 1 myr 1 high resolution color reflectance records of kc01 and kc01b calabrian ridge ionian sea are presented and compared with a modified spliced high resolution color reflectance record of ocean drilling program odp site 964 this comparison revealed that kc01b is characterized by intensive deformation between 27 and 28 5 m piston depth and that some sapropels are tectonically reduced in thickness moreover the piston coring has caused considerable stretching in the top of kc01 and kc01b using a new splice of odp site 964 as guide previous astronomical tuned timescales of kc01b and odp site 964 were evaluated this evaluation resulted in a new sapropel based astronomical timescale for the last 1 1 myr the new timescale implies a much more uniform change in sedimentation rate for the ionian sea cores two prominent excursions to lighter values in the 18o record of the planktonic foraminiferal species globigerinoides ruber occur during marine isotopic stages 12 and 16 applying the new timescale these shifts correspond with maxima in obliquity and are punctuated by minima in the precession cycle they are absent in global ice volume records and are interpreted as reflecting a summer low salinity surface water lens that floats on top of extremely saline intermediate and deep waters at times of the very low sea levels during these glacial periods all biostratigraphic and magnetostratigraphic events found in kc01b and odp site 964 were re dated according to the new timescale and the ages of 33 tephra layers were reviewed the new ages for the calabrian ridge 2 and 3 magnetic events in the brunhes are concordant with minima in the global sint800 composite record derived from worldwide deep sea records of relative paleointensity and have been attributed to the big lost and la palma excursions respectively

plinian fall deposits from vulsini volcanic district central italy stratigraphic investigations of the vulsini volcanic district indicate the existence of five prominent plinian fall deposits deposited over a period of about 0 34 ma the oldest deposit basal pumices crops out mainly in the peripheral areas and is one of the largest plinian events in the vulsini district with a volume of about 9 km3 and a calculated column height exceeding 30 km subcircular patterns of isopachs and isopleths around the bolsena lake indicate emplacement in wind free conditions and suggest a source vent location in the northernmost sector of the present bolsena lake where it is possible that an older central volcanic structure existed the four younger plinian fall deposits are related to bolsena activity the oldest of these named the ponticello and orvieto bagnoregio pumices are mainly distributed on the north eastern sector of the vulsini district their volumes are an order of magnitude lower than that of the basal unit and the estimated column heights do not exceed 20 km the younger ospedaletto pumice deposit has a ne sw dispersal axis whereas the youngest casetta pumice deposit is found only in the north eastern sector of the district their estimated volumes are respectively 1 2 and 0 1 km3 whereas the inferred vent areas appear to be located slightly to the east of the ponticello and orvieto bagnoregio pumice deposit source areas the chronology of the ospedaletto and casetta pumices indicates that the final plinian activity from the bolsena complex is contemporaneous with the latera activity the decreasing volumes from the oldest to the youngest units together with the progressive shifting northeastwards of the source vents may be related to the volcano tectonic subsidence of the bolsena area the source vents for the post basal pumices events are mainly clustered just north of bolsena village where the greatest displacement during subsidence occurred accordingly source vent shifting appears to be related to the progressive opening of normal faults from the inner to the outer margin of the bolsena depression

an exceptionally thick middle pleistocene tephra layer from epirus greece abstract a newly recognized 2 m thick trachytic volcanic ash deposit from northwestern greece is dated at 374 000 7000 yr and correlated with the middle pleistocene volcanic activity of central italy the deposit represents ash fallout from one of the largest volcanic eruptions in europe of the past 400 000 yr and should provide an important stratigraphic marker within the poorly dated middle pleistocene deposits of italy and greece