Coasts around the world are affected by high-energy wave events like storm surges or tsunamis. By... more Coasts around the world are affected by high-energy wave events like storm surges or tsunamis. By focusing on tsunami impacts, we investigate tsunami-induced transport of boulders by an interdisciplinary combination of field observations, laboratory experiments and advanced numerical modelling. In phase 1 of the project we conduct physical laboratory experiments based on real-world data. Following the experimental phase we will develop an enhanced numerical boulder transport model (BTM) based on an existing two-phase model.
Although extreme-wave events are frequent along the northwestern coast of Western Australia and t... more Although extreme-wave events are frequent along the northwestern coast of Western Australia and tsunamis in 1994 and 2006 induced considerable coastal flooding locally, robust stratigraphical evidence of prehistoric tropical cyclones and tsunamis from this area is lacking. Based on the analyses of X-ray computed microtomography (μCT) of oriented sediment cores, multi-proxy sediment and microfaunal analyses, optically stimulated luminescence (OSL) and 14C-AMS dating, this study presents detailed investigations on an allochthonous sand layer of marine origin found in a back-barrier depression on the NW Cape Range peninsula. The event layer consists of material from the adjacent beach and dune, fines and thins inland, and was traced up to ~400m onshore. Although a cyclone-induced origin cannot entirely be ruled out, the particular architecture and fabric of the sediment, rip-up clasts and three subunits point to deposition by a tsunami. As such, it represents the first stratigraphical evidence of a prehistoric, mid-Holocene tsunami in NW Western Australia. It was OSL-dated to 5400–4300years ago, thus postdating the regional mid-Holocene sea-level highstand.
Proceedings of the Seminar for Arabian Studies, 2016
The Asaila region (al-Usaylah) in south-western Qatar comprises a prominent solution-collapse dep... more The Asaila region (al-Usaylah) in south-western Qatar comprises a prominent solution-collapse depression filled with Quaternary aeolian sand and surrounding Tertiary limestone plateaus. Intensive systematic field walking in this area led to the identification of a total of 237 localities with evidence of past human activities. Most numerous finds are flint artefact scatters and single pieces of flint artefacts. Based on technological and typological studies, the majority of these artefact assemblages can be related to the Early Neolithic Qatar-B industries and the Middle Neolithic. The conspicuous absence of material remains that can be dated to the time period between the Chalcolithic and the Classical period plausibly suggests a decrease in human activities for more than five millennia. It was not until the Islamic period that the Asaila region became intensively occupied again.
Washover fans typically form due to barrier overwash or breaching and coastal inundation and gene... more Washover fans typically form due to barrier overwash or breaching and coastal inundation and generally represent geomorphological and depositional evidence of intense storms. Few studies have investigated the chronostratigraphy of washover fans in order to infer magnitude/frequency patterns of extreme-wave events over longer time scales. Here we present new data on the chronostratigraphy of late Holocene washover fans in the Exmouth Gulf (Western Australia) by using ground penetrating radar and unmanned aerial vehicle (UAV) survey techniques, as well as geomorphological, sedimentological and chronological investigations. This study aims to (i) provide a detailed characterization of the washover fans' geomorphology and stratigraphical architecture; (ii) document depositional processes involved in their formation; (iii) establish a chronostratigraphy based on optically stimulated luminescence (OSL); and (iv) understand the significance of the washover fans for recording past tropical cyclone (TC) activity. The fans consist of multiple sequences of sand, shell debris and coral rubble comprising depositional units related to TC-induced inundation. The units are separated by palaeosurfaces with incipient soil formation, formed during periods of reduced depositional activity. In combination with the interpretation of a UAV-based high-resolution digital surface model, multiple phases of reactivation are inferred. OSL results allow the establishment of a local long-term TC record and suggest storm-induced deposition at ∼170, ∼360, ∼850 and ∼1300 years ago. Further units were dated to ∼1950, ∼2300, and ∼2850 years ago. The chronology of TC events is consistent with other work relating TC activity with El Niño Southern Oscillation (ENSO) and sea surface temperature (SST) patterns, corroborating the regional palaeotempestological relevance of this unique geomorphological record.
Reliable age dating of coastal sedimentary landforms is crucial for inferring storm frequencies a... more Reliable age dating of coastal sedimentary landforms is crucial for inferring storm frequencies and magnitudes from geological archives. However, in highly energetic coastal settings, radiocarbon dating is often biased by reworking and/or poorly constrained marine reservoir effects. Due to this, most cyclone-driven sediment archives from the semiarid coast of NW Australia – a region frequently affected by tropical cyclones but with a historical record limited to ∼150 a, and therefore strongly in need of long-term data inferred from geological evidence – are affected by chronological inaccuracies. Optically stimulated luminescence dating (OSL) may overcome these shortcomings by dating the transport of sediment directly. In turn it may be related to other challenges when applied to cyclone deposits from semiarid environments. The cyclone-induced washover fans at Point Lefroy, NW Australia, are composed of a heterogeneous mixture of coral fragments, shell hash and siliciclastic sand. This makes them particularly prone to high dose scatter resulting from a combination of partial bleaching, sediment mixing and dose-rate heterogeneity. The washover fans are further characterised by a discontinuous nature of cyclone deposition, as indicated by erosional features and macroscopic brunification horizons. By using a combination of quartz single grain dating, autoradiography, alpha counting and gamma spectrometry, sediment mixing and dose rate heterogeneity are identified as the main sources of dose scatter. The resulting chronology allows us to discriminate at least four well constrained phases of washover fan activity at ∼180, ∼360, ∼870, and ∼1300 a ago. Older but less well constrained activity phases occurred ∼1950, ∼2300, and ∼2830 a ago. While these phases of increased cyclone activity correlate with depositional units separated by potential palaeosols, OSL ages, quasi-continuous portable OSL reader measurements and gamma spectrometry measured with increased sampling resolution point to deposition of distinct washover units within a very short period of time. However, unambiguous discrimination between deposition of individual units by single events and deposition by several cyclones within periods of only a few decades is currently not possible.
The occurrence of athalassic foraminiferal species, along with the brackish-water ostracod Cyprid... more The occurrence of athalassic foraminiferal species, along with the brackish-water ostracod Cyprideis torosa, the barnacle Amphibalanus amphitrite, and brackish-water gastropods, prove the existence of a saline lake at Tayma, northern Saudi Arabia, during the early to mid-Holocene. Outcrops at the former shoreline, as well as a single sediment core, allow a reconstruction of the history of the main lake phase. Whereas these outcrops contain masses of calcareous micro- and macrofossils, the core from the modern sabkha does not.Four foraminiferal species were identified: Ammonia tepida is dominant, Quinqueloculina seminula is common, Flintinoides labiosa and Discorinopsis aguayoi are rare. Sieve-pore analysis and shell chemistry of C. torosa, as well as varying but generally high proportions of test anomalies (up to 50\%) in foraminifers, indicate fluctuating, mostly hypersaline lacustrine conditions. We suggest, based on these results and on a literature overview on the worldwide distribution of Quaternary athalassic foraminifer taxa, that a combination of low diversity, exclusively marginal marine taxa, combined with occurrences of test anomalies \>10\% can be used to recognize athalassic saline waters in the fossil record.
Past coastal flooding events may be inferred from geomorphic and sedimentary archives, including ... more Past coastal flooding events may be inferred from geomorphic and sedimentary archives, including particular landforms (e.g., beach ridges, washover fans), deposits (e.g., washover sediments in lagoons) or erosional features (e.g., erosional scarps within strandplains). In Giralia Bay, southern Exmouth Gulf (Western Australia), sandy ridge sequences in supratidal elevations form the landward margin of extensive mudflats. The formation of these ridges is assumed to be mainly driven by tropical cyclones (TCs), although their depositional processes need to be clarified. We investigated the supratidal sandy ridge sequence in Giralia Bay by carrying out process monitoring, geomorphological mapping by means of an unmanned aerial vehicle survey, as well as sedimentological and geochronological investigations and multivariate statistics. Based on the resulting data, this study aims at (i) identifying the most important driving processes to form the sandy ridges; (ii) establishing their chronostratigraphy; and (iii) understanding their significance for recording past TC activity. Trench excavations revealed sandy units that are interbedded with mud layers at the base, similar to the present distal mudflat sediments. On top, mud intercalations recede, and sand layers of varying grain size distribution dominate. In the upper part of the trenches, younger sediment layers onlap older ones documenting the stepwise seaward accretion of the ridges onto the mudflat. While our data suggests that tidal processes have only limited effects on ridge activity, sediment transport, erosion and deposition seems to be driven by both TC-induced storm surges and high magnitude precipitation events causing surface discharge. Most accretionary sand units are thus assumed to represent events of morphodynamic activity during TC-induced flooding since the mid-Holocene. Ridge activity is recorded in a roughly decadal resolution and over historical as well as prehistorical/Holocene time scales. While the ridges do not represent beach or chenier ridges sensu stricto, they may be described as chenier-type ridges due to their stratigraphical architecture. Ridge evolution, however, over a millennial time scale seems to be indicated by the landward rise of the sequence possibly corresponding to the mid-Holocene sea-level highstand of Western Australia of at least 1–2m above present mean sea level.
Dating the transport/deposition time of supratidal coarse-clast deposits is difficult, limiting t... more Dating the transport/deposition time of supratidal coarse-clast deposits is difficult, limiting their value for inferring frequency-magnitude patterns of high-energy wave events. On Bonaire (Leeward Antilles, Caribbean), these deposits form prominent landforms, and transport by one or several Holocene tsunamis is assumed at least for the largest clasts. Although a large dataset of 14C and electron spin resonance (ESR) ages is available for major coral rubble ridges and ramparts, it is still debated whether these data reflect the timing of major events, and how these datasets are biased by the reworking of coral fragments. As an attempt to overcome the current challenges for dating the dislocation of singular boulders, three distinct dating methods are implemented and compared: (i) 14C dating of boring bivalves attached to the boulders; (ii) 230Th/U dating of post-depositional, secondary calcite flowstone and subaerial microbialites at the underside of the boulders; and (iii) surface exposure dating of overturned boulders via 36Cl concentration measurements in corals. Approaches (ii) and (iii) have never been applied to coastal boulder deposits so far. The three 14C age estimates are older than 40ka, i.e. most probably beyond the applicability of the method, which is attributed to post-depositional diagenetic processes, shedding doubt on the usefulness of this method in the local context. The remarkably convergent 230Th/U ages, all pointing to the Late Holocene period (1.0–1.6ka), are minimum ages for the transport event(s). The microbialite sample yields an age of 1.23±0.23ka and both flowstone samples are in stratigraphic order: the older (onset of carbonate precipitation) and younger flowstone layers yield ages of 1.59±0.03 and 1.23±0.03ka, respectively. Four coral samples collected from the topside of overturned boulders yielded similar 36Cl concentration measurements. However, the computed ages are affected by large uncertainties, mostly due to the high natural chlorine concentration. After correction for the inherited component and chemical denudation since platform emergence (inducing additional uncertainty), the calculated 36Cl ages cluster between 2.5±1.3 and 3.0±1.4ka for three of four boulders whilst the fourth one yields an age of 6.1±1.8ka, probably related to a higher inheritance. These 230Th/U and 36Cl age estimates are coherent with a suggested tsunami age of <3.3ka obtained from the investigation of allochthonous shell horizons in sediment cores of northwestern Bonaire. Whilst 230Th/U dating of post-depositional calcite flowstone appears to be the most robust and/or accurate approach, these results illustrate the potential and current limitations of the applied methods for dating the dislocation of supralittoral boulders in carbonate-reef settings.
After the deceleration of the postglacial marine transgression, the German North Sea coast was su... more After the deceleration of the postglacial marine transgression, the German North Sea coast was subject to deposition of a complex pattern of subtidal to terrestrial facies. This study aims at reconstructing these facies changes in the `Land Wursten' region (Lower Saxony) by focussing on so-called dwog horizons (incipient soil horizons of the pre-engineered salt marshes). We explore their implications for relative sea-level reconstructions and their indication for early settlement activities. Archive drilling data (1960, provided by the `Landesamt f{\"u}r Bergbau, Energie und Geologie') were analysed to create five high-resolution stratigraphic cross sections. Three new drilling records were subjected to sedimentological and microfaunal investigations and interpreted to verify and calibrate the archive data. Two dwog horizons were found and 14C-AMS dated. We found basal salt marsh deposits inundated by a high-energy event and covered by tidal flat sediments. The thick tidal flat unit is again overlain by salt marsh deposits indicating the transition from a shallow marine to a terrestrial environment where dwogs were developed and covered by episodic marine incursions. The ages of the dwogs (1128--969 cal BC; cal AD 1426--1467) do not correlate with known layers of adjacent settlement sites and are critically discussed. However, we show that they correlate with phases of stagnant regional relative sea level (RSL) and can be used as RSL indicators. The combined archive and modern data provide valuable information for the RSL reconstruction and palaeoenvironmental changes. However, further research is recommended to accomplish more detailed information about coastal response during the Holocene sea-level changes and implications for settlement dynamics.
Enzel et al. (2015) reassess sedimentary records of Early to Mid-Holocene lake sites in Arabia ba... more Enzel et al. (2015) reassess sedimentary records of Early to Mid-Holocene lake sites in Arabia based on a reinterpretation of published multiproxy data and a qualitative analysis of satellite imagery. The authors conclude that these sites represent palaeo-wetland environments rather than palaeolakes and that the majority of the Arabian Peninsula experienced no or, if at all, only a very minor increase of rainfall at that time mainly due to eastward expansion of the East African Summer Monsoon. We disagree with their reassessment and identify several cases where unequivocal evidence for early Late Pleistocene and Early to Mid-Holocene perennial lake environments in Arabia, lasting for centuries to millennia, was neglected by Enzel et al. (2015). Here we summarize findings which indicate the presence of lakes from the sites of Jubbah, Tayma, Mundafan (all Saudi Arabia), Wahalah, Awafi (both UAE), and the Wahiba Sands (Oman), supported by evidence including occurrence of barnacle colonies in living position, remnant bioclastic shoreline deposits, undisturbed varve formation, shallowing-up lacustrine sequences, various aquatic freshwater, brackish and saline micro- and macrofossils, such as ichnofaunal remains, which are the result of prolonged field-based research. While the precise depth, hydrology and ecology of these water bodies is still not entirely resolved, their perennial nature is indicative of a markedly increased precipitation regime, which, in combination with more abundant groundwater and increased spring outflow in terminal basins fed by charged aquifers, was sufficient to overcome evaporative losses. The palaeolakes' influence on sustaining prehistoric populations is corroborated by the presence of rich archaeological evidence.
Coasts worldwide experience considerable population pressure and the demand for reliable hazard m... more Coasts worldwide experience considerable population pressure and the demand for reliable hazard management, such as of tsunamis, increases. Tsunami hazard assessment requires information on long-term patterns of frequency and magnitude, which are best explained by inverse power-law functions. In areas with a short historical documentation, long-term patterns must therefore be based on geological traces. The Caribbean tsunami hazard is exemplified by > 80 events triggered by earthquakes, volcanic activity, or mass wasting within the region or in the far-field during the last 520 years. Most of these tsunamis had regional or local impacts. Based on two numerical hydrodynamic models of tsunamis spawning at the Muertos Thrust Belt (MTB) and the South Caribbean Deformed Belt (SCBD), which are two scenarios only marginally considered so far, we show that pan-Caribbean tsunamis can also be taken into account. We furthermore review almost 60 sites for possible geological evidence of tsunamis in the Caribbean including fine-grained subsurface deposits and subaerial coarse clasts, and re-evaluate their implications for tsunami hazard assessment against state-of-the-art models of onshore sediment deposition by tsunamis and extreme storms. The records span the mid- to late Holocene, with very few exceptions of Pleistocene age.
Only a limited number of reliable palaeotsunami records with consistent and robust age control were identified, hampering inter-island or interregional correlation of deposits of the same event. Distinguishing between storm and tsunami transport of solitary boulders is very difficult in most cases, whereas those clasts arranged as ridges or incorporated into polymodal ridge complexes, which line many windward coasts of the Caribbean, can mainly be attributed to long-term formation during strong storms, overprinting potential tsunami signatures. The quantification of tsunami flooding parameters such as flow depth, inundation distance or flow velocities, by applying inverse and forward numerical models of sediment transport is still very limited and needs to be extended in the future. Likewise, sediment-derived hazard implications still await implementation in spatial planning. As extreme-wave deposits are clearly understudied in the Caribbean, there is great potential for coastal hazard assessment to be developed and improved. Thus, further studies using common standards of high-resolution methods of bedform and stratigraphical documentation and robust chronological models with independent age control, combined with refined inverse and forward models of sediment transport and deposition are required to reconstruct reliable patterns of magnitude and frequency of palaeotsunamis in the Caribbean and to map hazard-prone areas. To date, known palaeotsunami deposits from the Caribbean probably represent only a fraction of actually happened prehistoric tsunamis and, therefore, do not reflect major tsunami inundations of the past adequately.
A general lack of accounts of palaeo-tsunami deposits in back barrier environments throughout the... more A general lack of accounts of palaeo-tsunami deposits in back barrier environments throughout the Caribbean and diverging and conflicting interpretation of onshore coarse-clast deposits and landforms on the Leeward Netherlands Antilles (Bonaire, Curaçao, Aruba) encouraged the investigation of coastal stratigraphies along the coast of Bonaire. This work was conducted in order to (i) identify overwash deposits and reconstruct the regional history of high-energy wave events and (ii) provide a scientific basis for local hazard assessment. Vibracores and push cores at the windward (Playa Grandi, Lagun) and leeward coast (Saliña Tam, Klein Bonaire) were analyzed in terms of sedimentary characteristics, geochemical composition and fossil content. The coring sites in exposure to wave energy, foreshore morphology, sediment budgets, relief gradient and vegetation cover. Accordingly the pattern of subsurface overwash deposits varies significantly from site to site depending on exposure direction. For instance, although a prominent layer of sand and shell debris identified at the Lagun embayment (2000-1700 BP) has a counterpart at the sheltered lagoon of Saliña Tam, it is obviously absent at the northern coast. Along the entire island major layers of extreme wave deposits were radiocarbon dated to around 3300 BP, 2000-1700 BP and >500 BP. Sedimentary characteristics, bedforms and geochemical signatures did not provide unequivocal evidence for either tsunami or hurricane storm surge. However, evidence from the taphonomic characteristics of mollusc shells (articulation, fragmentation, rounding, encrustations, abrasion/dissolution) found within candidate coarse sediment layers and by comparison with the marginal sediment input of recent category 4/5 hurricane storm surges, the deposits were classified as representatives for palaeo-tsunami events.
Fields of dislodged boulders and blocks record catastrophic coastal flooding during strong storms... more Fields of dislodged boulders and blocks record catastrophic coastal flooding during strong storms or tsunamis and play a pivotal role in coastal hazard assessment. Along the rocky carbonate coast of Eastern Samar (Philippines) we documented longshore transport of a block of 180 t and boulders (up to 23.5 t) shifted upslope to elevations of up to 10m above mean lower low water level during Supertyphoon Haiyan on 8 November 2013. Initiation-of-motion approaches indicate that boulder dislocation occurred with flow velocities of 8.9– 9.6ms1, which significantly exceeds depth-averaged flow velocities of a local coupled hydrodynamic and wave model (Delft3D) of the typhoon with a maximum < 1.5ms1. These results, in combination with recently published phase-resolving wave models, support the hypothesis that infragravity waves induced by the typhoon were responsible for the remarkable flooding pattern in Eastern Samar, which are not resolved in phase-averaged storm surge models. Our findings show that tsunamis and hydrodynamic conditions induced by tropical cyclones may shift boulders of similar size and, therefore, demand a careful re-evaluation of storm-related transport where it, based on the boulder’s sheer size, has previously been ascribed to tsunamis.
Résumé/Abstract The Iron Age sanctuary of Poseidon on the rim of the coastal plain of Pamisos riv... more Résumé/Abstract The Iron Age sanctuary of Poseidon on the rim of the coastal plain of Pamisos river, partly excavated in 1969 by P. Themelis, was built on the crest of a barrier beach which had been deposited by the sea during the late 3rd mill. BC and then was ...
Detailed investigations on the Holocene stratigraphy of the lower Messenian plain (SW Peloponnese... more Detailed investigations on the Holocene stratigraphy of the lower Messenian plain (SW Peloponnese, Greece) carried out within the framework of a geoarchaeological study on the Protogeometric Poseidon Sanctuary of Akovitika indicate significant shoreline fluctuations during Holocene times. Sedimentary, geochemical, mineralogical, and microfossil analyses of 18 vibracores document a maximum landward shoreline displacement around 3000 BC. Subsequently, increased sediment loads entering
Coasts around the world are affected by high-energy wave events like storm surges or tsunamis. By... more Coasts around the world are affected by high-energy wave events like storm surges or tsunamis. By focusing on tsunami impacts, we investigate tsunami-induced transport of boulders by an interdisciplinary combination of field observations, laboratory experiments and advanced numerical modelling. In phase 1 of the project we conduct physical laboratory experiments based on real-world data. Following the experimental phase we will develop an enhanced numerical boulder transport model (BTM) based on an existing two-phase model.
Although extreme-wave events are frequent along the northwestern coast of Western Australia and t... more Although extreme-wave events are frequent along the northwestern coast of Western Australia and tsunamis in 1994 and 2006 induced considerable coastal flooding locally, robust stratigraphical evidence of prehistoric tropical cyclones and tsunamis from this area is lacking. Based on the analyses of X-ray computed microtomography (μCT) of oriented sediment cores, multi-proxy sediment and microfaunal analyses, optically stimulated luminescence (OSL) and 14C-AMS dating, this study presents detailed investigations on an allochthonous sand layer of marine origin found in a back-barrier depression on the NW Cape Range peninsula. The event layer consists of material from the adjacent beach and dune, fines and thins inland, and was traced up to ~400m onshore. Although a cyclone-induced origin cannot entirely be ruled out, the particular architecture and fabric of the sediment, rip-up clasts and three subunits point to deposition by a tsunami. As such, it represents the first stratigraphical evidence of a prehistoric, mid-Holocene tsunami in NW Western Australia. It was OSL-dated to 5400–4300years ago, thus postdating the regional mid-Holocene sea-level highstand.
Proceedings of the Seminar for Arabian Studies, 2016
The Asaila region (al-Usaylah) in south-western Qatar comprises a prominent solution-collapse dep... more The Asaila region (al-Usaylah) in south-western Qatar comprises a prominent solution-collapse depression filled with Quaternary aeolian sand and surrounding Tertiary limestone plateaus. Intensive systematic field walking in this area led to the identification of a total of 237 localities with evidence of past human activities. Most numerous finds are flint artefact scatters and single pieces of flint artefacts. Based on technological and typological studies, the majority of these artefact assemblages can be related to the Early Neolithic Qatar-B industries and the Middle Neolithic. The conspicuous absence of material remains that can be dated to the time period between the Chalcolithic and the Classical period plausibly suggests a decrease in human activities for more than five millennia. It was not until the Islamic period that the Asaila region became intensively occupied again.
Washover fans typically form due to barrier overwash or breaching and coastal inundation and gene... more Washover fans typically form due to barrier overwash or breaching and coastal inundation and generally represent geomorphological and depositional evidence of intense storms. Few studies have investigated the chronostratigraphy of washover fans in order to infer magnitude/frequency patterns of extreme-wave events over longer time scales. Here we present new data on the chronostratigraphy of late Holocene washover fans in the Exmouth Gulf (Western Australia) by using ground penetrating radar and unmanned aerial vehicle (UAV) survey techniques, as well as geomorphological, sedimentological and chronological investigations. This study aims to (i) provide a detailed characterization of the washover fans' geomorphology and stratigraphical architecture; (ii) document depositional processes involved in their formation; (iii) establish a chronostratigraphy based on optically stimulated luminescence (OSL); and (iv) understand the significance of the washover fans for recording past tropical cyclone (TC) activity. The fans consist of multiple sequences of sand, shell debris and coral rubble comprising depositional units related to TC-induced inundation. The units are separated by palaeosurfaces with incipient soil formation, formed during periods of reduced depositional activity. In combination with the interpretation of a UAV-based high-resolution digital surface model, multiple phases of reactivation are inferred. OSL results allow the establishment of a local long-term TC record and suggest storm-induced deposition at ∼170, ∼360, ∼850 and ∼1300 years ago. Further units were dated to ∼1950, ∼2300, and ∼2850 years ago. The chronology of TC events is consistent with other work relating TC activity with El Niño Southern Oscillation (ENSO) and sea surface temperature (SST) patterns, corroborating the regional palaeotempestological relevance of this unique geomorphological record.
Reliable age dating of coastal sedimentary landforms is crucial for inferring storm frequencies a... more Reliable age dating of coastal sedimentary landforms is crucial for inferring storm frequencies and magnitudes from geological archives. However, in highly energetic coastal settings, radiocarbon dating is often biased by reworking and/or poorly constrained marine reservoir effects. Due to this, most cyclone-driven sediment archives from the semiarid coast of NW Australia – a region frequently affected by tropical cyclones but with a historical record limited to ∼150 a, and therefore strongly in need of long-term data inferred from geological evidence – are affected by chronological inaccuracies. Optically stimulated luminescence dating (OSL) may overcome these shortcomings by dating the transport of sediment directly. In turn it may be related to other challenges when applied to cyclone deposits from semiarid environments. The cyclone-induced washover fans at Point Lefroy, NW Australia, are composed of a heterogeneous mixture of coral fragments, shell hash and siliciclastic sand. This makes them particularly prone to high dose scatter resulting from a combination of partial bleaching, sediment mixing and dose-rate heterogeneity. The washover fans are further characterised by a discontinuous nature of cyclone deposition, as indicated by erosional features and macroscopic brunification horizons. By using a combination of quartz single grain dating, autoradiography, alpha counting and gamma spectrometry, sediment mixing and dose rate heterogeneity are identified as the main sources of dose scatter. The resulting chronology allows us to discriminate at least four well constrained phases of washover fan activity at ∼180, ∼360, ∼870, and ∼1300 a ago. Older but less well constrained activity phases occurred ∼1950, ∼2300, and ∼2830 a ago. While these phases of increased cyclone activity correlate with depositional units separated by potential palaeosols, OSL ages, quasi-continuous portable OSL reader measurements and gamma spectrometry measured with increased sampling resolution point to deposition of distinct washover units within a very short period of time. However, unambiguous discrimination between deposition of individual units by single events and deposition by several cyclones within periods of only a few decades is currently not possible.
The occurrence of athalassic foraminiferal species, along with the brackish-water ostracod Cyprid... more The occurrence of athalassic foraminiferal species, along with the brackish-water ostracod Cyprideis torosa, the barnacle Amphibalanus amphitrite, and brackish-water gastropods, prove the existence of a saline lake at Tayma, northern Saudi Arabia, during the early to mid-Holocene. Outcrops at the former shoreline, as well as a single sediment core, allow a reconstruction of the history of the main lake phase. Whereas these outcrops contain masses of calcareous micro- and macrofossils, the core from the modern sabkha does not.Four foraminiferal species were identified: Ammonia tepida is dominant, Quinqueloculina seminula is common, Flintinoides labiosa and Discorinopsis aguayoi are rare. Sieve-pore analysis and shell chemistry of C. torosa, as well as varying but generally high proportions of test anomalies (up to 50\%) in foraminifers, indicate fluctuating, mostly hypersaline lacustrine conditions. We suggest, based on these results and on a literature overview on the worldwide distribution of Quaternary athalassic foraminifer taxa, that a combination of low diversity, exclusively marginal marine taxa, combined with occurrences of test anomalies \>10\% can be used to recognize athalassic saline waters in the fossil record.
Past coastal flooding events may be inferred from geomorphic and sedimentary archives, including ... more Past coastal flooding events may be inferred from geomorphic and sedimentary archives, including particular landforms (e.g., beach ridges, washover fans), deposits (e.g., washover sediments in lagoons) or erosional features (e.g., erosional scarps within strandplains). In Giralia Bay, southern Exmouth Gulf (Western Australia), sandy ridge sequences in supratidal elevations form the landward margin of extensive mudflats. The formation of these ridges is assumed to be mainly driven by tropical cyclones (TCs), although their depositional processes need to be clarified. We investigated the supratidal sandy ridge sequence in Giralia Bay by carrying out process monitoring, geomorphological mapping by means of an unmanned aerial vehicle survey, as well as sedimentological and geochronological investigations and multivariate statistics. Based on the resulting data, this study aims at (i) identifying the most important driving processes to form the sandy ridges; (ii) establishing their chronostratigraphy; and (iii) understanding their significance for recording past TC activity. Trench excavations revealed sandy units that are interbedded with mud layers at the base, similar to the present distal mudflat sediments. On top, mud intercalations recede, and sand layers of varying grain size distribution dominate. In the upper part of the trenches, younger sediment layers onlap older ones documenting the stepwise seaward accretion of the ridges onto the mudflat. While our data suggests that tidal processes have only limited effects on ridge activity, sediment transport, erosion and deposition seems to be driven by both TC-induced storm surges and high magnitude precipitation events causing surface discharge. Most accretionary sand units are thus assumed to represent events of morphodynamic activity during TC-induced flooding since the mid-Holocene. Ridge activity is recorded in a roughly decadal resolution and over historical as well as prehistorical/Holocene time scales. While the ridges do not represent beach or chenier ridges sensu stricto, they may be described as chenier-type ridges due to their stratigraphical architecture. Ridge evolution, however, over a millennial time scale seems to be indicated by the landward rise of the sequence possibly corresponding to the mid-Holocene sea-level highstand of Western Australia of at least 1–2m above present mean sea level.
Dating the transport/deposition time of supratidal coarse-clast deposits is difficult, limiting t... more Dating the transport/deposition time of supratidal coarse-clast deposits is difficult, limiting their value for inferring frequency-magnitude patterns of high-energy wave events. On Bonaire (Leeward Antilles, Caribbean), these deposits form prominent landforms, and transport by one or several Holocene tsunamis is assumed at least for the largest clasts. Although a large dataset of 14C and electron spin resonance (ESR) ages is available for major coral rubble ridges and ramparts, it is still debated whether these data reflect the timing of major events, and how these datasets are biased by the reworking of coral fragments. As an attempt to overcome the current challenges for dating the dislocation of singular boulders, three distinct dating methods are implemented and compared: (i) 14C dating of boring bivalves attached to the boulders; (ii) 230Th/U dating of post-depositional, secondary calcite flowstone and subaerial microbialites at the underside of the boulders; and (iii) surface exposure dating of overturned boulders via 36Cl concentration measurements in corals. Approaches (ii) and (iii) have never been applied to coastal boulder deposits so far. The three 14C age estimates are older than 40ka, i.e. most probably beyond the applicability of the method, which is attributed to post-depositional diagenetic processes, shedding doubt on the usefulness of this method in the local context. The remarkably convergent 230Th/U ages, all pointing to the Late Holocene period (1.0–1.6ka), are minimum ages for the transport event(s). The microbialite sample yields an age of 1.23±0.23ka and both flowstone samples are in stratigraphic order: the older (onset of carbonate precipitation) and younger flowstone layers yield ages of 1.59±0.03 and 1.23±0.03ka, respectively. Four coral samples collected from the topside of overturned boulders yielded similar 36Cl concentration measurements. However, the computed ages are affected by large uncertainties, mostly due to the high natural chlorine concentration. After correction for the inherited component and chemical denudation since platform emergence (inducing additional uncertainty), the calculated 36Cl ages cluster between 2.5±1.3 and 3.0±1.4ka for three of four boulders whilst the fourth one yields an age of 6.1±1.8ka, probably related to a higher inheritance. These 230Th/U and 36Cl age estimates are coherent with a suggested tsunami age of <3.3ka obtained from the investigation of allochthonous shell horizons in sediment cores of northwestern Bonaire. Whilst 230Th/U dating of post-depositional calcite flowstone appears to be the most robust and/or accurate approach, these results illustrate the potential and current limitations of the applied methods for dating the dislocation of supralittoral boulders in carbonate-reef settings.
After the deceleration of the postglacial marine transgression, the German North Sea coast was su... more After the deceleration of the postglacial marine transgression, the German North Sea coast was subject to deposition of a complex pattern of subtidal to terrestrial facies. This study aims at reconstructing these facies changes in the `Land Wursten' region (Lower Saxony) by focussing on so-called dwog horizons (incipient soil horizons of the pre-engineered salt marshes). We explore their implications for relative sea-level reconstructions and their indication for early settlement activities. Archive drilling data (1960, provided by the `Landesamt f{\"u}r Bergbau, Energie und Geologie') were analysed to create five high-resolution stratigraphic cross sections. Three new drilling records were subjected to sedimentological and microfaunal investigations and interpreted to verify and calibrate the archive data. Two dwog horizons were found and 14C-AMS dated. We found basal salt marsh deposits inundated by a high-energy event and covered by tidal flat sediments. The thick tidal flat unit is again overlain by salt marsh deposits indicating the transition from a shallow marine to a terrestrial environment where dwogs were developed and covered by episodic marine incursions. The ages of the dwogs (1128--969 cal BC; cal AD 1426--1467) do not correlate with known layers of adjacent settlement sites and are critically discussed. However, we show that they correlate with phases of stagnant regional relative sea level (RSL) and can be used as RSL indicators. The combined archive and modern data provide valuable information for the RSL reconstruction and palaeoenvironmental changes. However, further research is recommended to accomplish more detailed information about coastal response during the Holocene sea-level changes and implications for settlement dynamics.
Enzel et al. (2015) reassess sedimentary records of Early to Mid-Holocene lake sites in Arabia ba... more Enzel et al. (2015) reassess sedimentary records of Early to Mid-Holocene lake sites in Arabia based on a reinterpretation of published multiproxy data and a qualitative analysis of satellite imagery. The authors conclude that these sites represent palaeo-wetland environments rather than palaeolakes and that the majority of the Arabian Peninsula experienced no or, if at all, only a very minor increase of rainfall at that time mainly due to eastward expansion of the East African Summer Monsoon. We disagree with their reassessment and identify several cases where unequivocal evidence for early Late Pleistocene and Early to Mid-Holocene perennial lake environments in Arabia, lasting for centuries to millennia, was neglected by Enzel et al. (2015). Here we summarize findings which indicate the presence of lakes from the sites of Jubbah, Tayma, Mundafan (all Saudi Arabia), Wahalah, Awafi (both UAE), and the Wahiba Sands (Oman), supported by evidence including occurrence of barnacle colonies in living position, remnant bioclastic shoreline deposits, undisturbed varve formation, shallowing-up lacustrine sequences, various aquatic freshwater, brackish and saline micro- and macrofossils, such as ichnofaunal remains, which are the result of prolonged field-based research. While the precise depth, hydrology and ecology of these water bodies is still not entirely resolved, their perennial nature is indicative of a markedly increased precipitation regime, which, in combination with more abundant groundwater and increased spring outflow in terminal basins fed by charged aquifers, was sufficient to overcome evaporative losses. The palaeolakes' influence on sustaining prehistoric populations is corroborated by the presence of rich archaeological evidence.
Coasts worldwide experience considerable population pressure and the demand for reliable hazard m... more Coasts worldwide experience considerable population pressure and the demand for reliable hazard management, such as of tsunamis, increases. Tsunami hazard assessment requires information on long-term patterns of frequency and magnitude, which are best explained by inverse power-law functions. In areas with a short historical documentation, long-term patterns must therefore be based on geological traces. The Caribbean tsunami hazard is exemplified by > 80 events triggered by earthquakes, volcanic activity, or mass wasting within the region or in the far-field during the last 520 years. Most of these tsunamis had regional or local impacts. Based on two numerical hydrodynamic models of tsunamis spawning at the Muertos Thrust Belt (MTB) and the South Caribbean Deformed Belt (SCBD), which are two scenarios only marginally considered so far, we show that pan-Caribbean tsunamis can also be taken into account. We furthermore review almost 60 sites for possible geological evidence of tsunamis in the Caribbean including fine-grained subsurface deposits and subaerial coarse clasts, and re-evaluate their implications for tsunami hazard assessment against state-of-the-art models of onshore sediment deposition by tsunamis and extreme storms. The records span the mid- to late Holocene, with very few exceptions of Pleistocene age.
Only a limited number of reliable palaeotsunami records with consistent and robust age control were identified, hampering inter-island or interregional correlation of deposits of the same event. Distinguishing between storm and tsunami transport of solitary boulders is very difficult in most cases, whereas those clasts arranged as ridges or incorporated into polymodal ridge complexes, which line many windward coasts of the Caribbean, can mainly be attributed to long-term formation during strong storms, overprinting potential tsunami signatures. The quantification of tsunami flooding parameters such as flow depth, inundation distance or flow velocities, by applying inverse and forward numerical models of sediment transport is still very limited and needs to be extended in the future. Likewise, sediment-derived hazard implications still await implementation in spatial planning. As extreme-wave deposits are clearly understudied in the Caribbean, there is great potential for coastal hazard assessment to be developed and improved. Thus, further studies using common standards of high-resolution methods of bedform and stratigraphical documentation and robust chronological models with independent age control, combined with refined inverse and forward models of sediment transport and deposition are required to reconstruct reliable patterns of magnitude and frequency of palaeotsunamis in the Caribbean and to map hazard-prone areas. To date, known palaeotsunami deposits from the Caribbean probably represent only a fraction of actually happened prehistoric tsunamis and, therefore, do not reflect major tsunami inundations of the past adequately.
A general lack of accounts of palaeo-tsunami deposits in back barrier environments throughout the... more A general lack of accounts of palaeo-tsunami deposits in back barrier environments throughout the Caribbean and diverging and conflicting interpretation of onshore coarse-clast deposits and landforms on the Leeward Netherlands Antilles (Bonaire, Curaçao, Aruba) encouraged the investigation of coastal stratigraphies along the coast of Bonaire. This work was conducted in order to (i) identify overwash deposits and reconstruct the regional history of high-energy wave events and (ii) provide a scientific basis for local hazard assessment. Vibracores and push cores at the windward (Playa Grandi, Lagun) and leeward coast (Saliña Tam, Klein Bonaire) were analyzed in terms of sedimentary characteristics, geochemical composition and fossil content. The coring sites in exposure to wave energy, foreshore morphology, sediment budgets, relief gradient and vegetation cover. Accordingly the pattern of subsurface overwash deposits varies significantly from site to site depending on exposure direction. For instance, although a prominent layer of sand and shell debris identified at the Lagun embayment (2000-1700 BP) has a counterpart at the sheltered lagoon of Saliña Tam, it is obviously absent at the northern coast. Along the entire island major layers of extreme wave deposits were radiocarbon dated to around 3300 BP, 2000-1700 BP and >500 BP. Sedimentary characteristics, bedforms and geochemical signatures did not provide unequivocal evidence for either tsunami or hurricane storm surge. However, evidence from the taphonomic characteristics of mollusc shells (articulation, fragmentation, rounding, encrustations, abrasion/dissolution) found within candidate coarse sediment layers and by comparison with the marginal sediment input of recent category 4/5 hurricane storm surges, the deposits were classified as representatives for palaeo-tsunami events.
Fields of dislodged boulders and blocks record catastrophic coastal flooding during strong storms... more Fields of dislodged boulders and blocks record catastrophic coastal flooding during strong storms or tsunamis and play a pivotal role in coastal hazard assessment. Along the rocky carbonate coast of Eastern Samar (Philippines) we documented longshore transport of a block of 180 t and boulders (up to 23.5 t) shifted upslope to elevations of up to 10m above mean lower low water level during Supertyphoon Haiyan on 8 November 2013. Initiation-of-motion approaches indicate that boulder dislocation occurred with flow velocities of 8.9– 9.6ms1, which significantly exceeds depth-averaged flow velocities of a local coupled hydrodynamic and wave model (Delft3D) of the typhoon with a maximum < 1.5ms1. These results, in combination with recently published phase-resolving wave models, support the hypothesis that infragravity waves induced by the typhoon were responsible for the remarkable flooding pattern in Eastern Samar, which are not resolved in phase-averaged storm surge models. Our findings show that tsunamis and hydrodynamic conditions induced by tropical cyclones may shift boulders of similar size and, therefore, demand a careful re-evaluation of storm-related transport where it, based on the boulder’s sheer size, has previously been ascribed to tsunamis.
Résumé/Abstract The Iron Age sanctuary of Poseidon on the rim of the coastal plain of Pamisos riv... more Résumé/Abstract The Iron Age sanctuary of Poseidon on the rim of the coastal plain of Pamisos river, partly excavated in 1969 by P. Themelis, was built on the crest of a barrier beach which had been deposited by the sea during the late 3rd mill. BC and then was ...
Detailed investigations on the Holocene stratigraphy of the lower Messenian plain (SW Peloponnese... more Detailed investigations on the Holocene stratigraphy of the lower Messenian plain (SW Peloponnese, Greece) carried out within the framework of a geoarchaeological study on the Protogeometric Poseidon Sanctuary of Akovitika indicate significant shoreline fluctuations during Holocene times. Sedimentary, geochemical, mineralogical, and microfossil analyses of 18 vibracores document a maximum landward shoreline displacement around 3000 BC. Subsequently, increased sediment loads entering
In Roman times, the stone and pottery production near Mayen in western Germany reached a very hig... more In Roman times, the stone and pottery production near Mayen in western Germany reached a very high intensity
which would have satisfied the needs of a much wider area. The rate and volume of production was unprecedented
and never reached the same level thereafter. The Segbach valley study site with an area of only a few square kilo-
metres offers a very special geoarchaeological archive. The Roman land use structures were completely preserved
under a 2 meter thick layer of sediment and are now partially exposed in a gully due to erosion.
Pedological, sedimentological and geophysical studies at the colluvium and floodplain sediments as well as relict
field structures showed that in the last 2500 years there has been a considerable human impact on both water and
sediment budgets. This also had various implications on the further development of water courses, soils and relief.
Evidence for the development of flood plain sediments can be traced as far back as the late La Tène period, the
Roman Iron Age, and since the Middle Ages.
On one particular south-facing slope we found evidence of recultivation measures on a former quarry tailing heap
dating from the Middle Ages. This and other human construction activities and land uses lead to a significant
change in erosion and sedimentation patterns. It is surprising that sedimentation in flood plains was largely absent
during the Roman Iron Age despite intensive land use. Evidence shows that flash flood events with intensive accu-
mulation of soil matter in flood plains only occurred during the High Middle Ages. Sediments from the late Middle
ages and the Modern Times are largely missing.
The research undertaken in Segbach valley not only offers new insights into specific local historical land uses
and land use changes but also fundamental knowledge about the principles and impacts of long-term human-
environment interactions.
(CC BY 3.0)
A geoarchaeology panel titled "Coastal geoarchaeology in the Mediterranean – on the interdependen... more A geoarchaeology panel titled "Coastal geoarchaeology in the Mediterranean – on the interdependence of landscape dynamics, harbour installations and economic prosperity in the littoral realm" will be organized as part of Session 2 "The impact of natural environmental factors on ancient economy: climate, landscape" of the 19th International Congress of Classical Archaeology, to be held at Cologne/Bonn (Germany), 22–26 May 2018. Any contribution related to this topic are welcome. Please submit your papers online through the conference website:
Coastal geoarchaeology in the Mediterranean – on the interdependence of landscape dynamics, harbour installations and economic prosperity in the littoral realm Organizers: Max Engel and Friederike Stock (University of Cologne) Mediterranean coastlines are highly dynamic geomorphic landscapes with lateral progradation of up to tens of kilometres in alluvial delta regions during the last 5000 years. After the significant deceleration of post-glacial eustatic sea-level rise around 7000-6000 years ago, a complex interplay of regional and local factors such as vertical tectonic movements, glacial isostatic rebound, sediment supply by rivers and coastal currents, deltaic compaction, and human intervention, led to locally different histories of coastal formation. As the coastal zone provided essential access to food, maritime commerce and colonisation activities, its dynamical nature had a significant impact on the prosperity of ancient communities. In fact, Mediterranean harbours as the gateways to the maritime realm were constantly threatened by gradual sedimentation, tectonic uplift or subsidence, as well as extreme events such as earthquakes or tsunamis. Many harbours became landlocked due to coastal progradation with fundamental repercussions on the political and economic status of ancient poleis. We invite any contributions studying the influence of the dynamic, physical coastal environment on human communities during Antiquity, may this influence be through gradual, long-term sedimentary or geomorphic processes, or episodic such as through earthquakes or tsunamis. We also invite contributions on any type of ancient human influence on the physical coastal environment including but not limited to the implementation of engineering measures or chemical or sedimentary imprints. All types of contributions are envisaged, including excavation-and field-based case studies, those comprising numerical models, synthesising reviews or advances in scientific methodology and techniques.
Final Report of the SQSP Project, a cooperation between Qatar Museums and the Orient-Department o... more Final Report of the SQSP Project, a cooperation between Qatar Museums and the Orient-Department of the German Archaeological Institute. The project deals with the results of the spring season 2014, archaeological record of the cultural heritage in Qatar.
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Papers by Max Engel
Only a limited number of reliable palaeotsunami records with consistent and robust age control were identified, hampering inter-island or interregional correlation of deposits of the same event. Distinguishing between storm and tsunami transport of solitary boulders is very difficult in most cases, whereas those clasts arranged as ridges or incorporated into polymodal ridge complexes, which line many windward coasts of the Caribbean, can mainly be attributed to long-term formation during strong storms, overprinting potential tsunami signatures. The quantification of tsunami flooding parameters such as flow depth, inundation distance or flow velocities, by applying inverse and forward numerical models of sediment transport is still very limited and needs to be extended in the future. Likewise, sediment-derived hazard implications still await implementation in spatial planning. As extreme-wave deposits are clearly understudied in the Caribbean, there is great potential for coastal hazard assessment to be developed and improved. Thus, further studies using common standards of high-resolution methods of bedform and stratigraphical documentation and robust chronological models with independent age control, combined with refined inverse and forward models of sediment transport and deposition are required to reconstruct reliable patterns of magnitude and frequency of palaeotsunamis in the Caribbean and to map hazard-prone areas. To date, known palaeotsunami deposits from the Caribbean probably represent only a fraction of actually happened prehistoric tsunamis and, therefore, do not reflect major tsunami inundations of the past adequately.
tsunamis and play a pivotal role in coastal hazard assessment. Along the rocky carbonate coast of Eastern Samar
(Philippines) we documented longshore transport of a block of 180 t and boulders (up to 23.5 t) shifted upslope
to elevations of up to 10m above mean lower low water level during Supertyphoon Haiyan on 8 November
2013. Initiation-of-motion approaches indicate that boulder dislocation occurred with flow velocities of 8.9–
9.6ms1, which significantly exceeds depth-averaged flow velocities of a local coupled hydrodynamic and
wave model (Delft3D) of the typhoon with a maximum < 1.5ms1. These results, in combination with recently
published phase-resolving wave models, support the hypothesis that infragravity waves induced by the typhoon
were responsible for the remarkable flooding pattern in Eastern Samar, which are not resolved in phase-averaged
storm surge models. Our findings show that tsunamis and hydrodynamic conditions induced by tropical cyclones
may shift boulders of similar size and, therefore, demand a careful re-evaluation of storm-related transport where
it, based on the boulder’s sheer size, has previously been ascribed to tsunamis.
Only a limited number of reliable palaeotsunami records with consistent and robust age control were identified, hampering inter-island or interregional correlation of deposits of the same event. Distinguishing between storm and tsunami transport of solitary boulders is very difficult in most cases, whereas those clasts arranged as ridges or incorporated into polymodal ridge complexes, which line many windward coasts of the Caribbean, can mainly be attributed to long-term formation during strong storms, overprinting potential tsunami signatures. The quantification of tsunami flooding parameters such as flow depth, inundation distance or flow velocities, by applying inverse and forward numerical models of sediment transport is still very limited and needs to be extended in the future. Likewise, sediment-derived hazard implications still await implementation in spatial planning. As extreme-wave deposits are clearly understudied in the Caribbean, there is great potential for coastal hazard assessment to be developed and improved. Thus, further studies using common standards of high-resolution methods of bedform and stratigraphical documentation and robust chronological models with independent age control, combined with refined inverse and forward models of sediment transport and deposition are required to reconstruct reliable patterns of magnitude and frequency of palaeotsunamis in the Caribbean and to map hazard-prone areas. To date, known palaeotsunami deposits from the Caribbean probably represent only a fraction of actually happened prehistoric tsunamis and, therefore, do not reflect major tsunami inundations of the past adequately.
tsunamis and play a pivotal role in coastal hazard assessment. Along the rocky carbonate coast of Eastern Samar
(Philippines) we documented longshore transport of a block of 180 t and boulders (up to 23.5 t) shifted upslope
to elevations of up to 10m above mean lower low water level during Supertyphoon Haiyan on 8 November
2013. Initiation-of-motion approaches indicate that boulder dislocation occurred with flow velocities of 8.9–
9.6ms1, which significantly exceeds depth-averaged flow velocities of a local coupled hydrodynamic and
wave model (Delft3D) of the typhoon with a maximum < 1.5ms1. These results, in combination with recently
published phase-resolving wave models, support the hypothesis that infragravity waves induced by the typhoon
were responsible for the remarkable flooding pattern in Eastern Samar, which are not resolved in phase-averaged
storm surge models. Our findings show that tsunamis and hydrodynamic conditions induced by tropical cyclones
may shift boulders of similar size and, therefore, demand a careful re-evaluation of storm-related transport where
it, based on the boulder’s sheer size, has previously been ascribed to tsunamis.
which would have satisfied the needs of a much wider area. The rate and volume of production was unprecedented
and never reached the same level thereafter. The Segbach valley study site with an area of only a few square kilo-
metres offers a very special geoarchaeological archive. The Roman land use structures were completely preserved
under a 2 meter thick layer of sediment and are now partially exposed in a gully due to erosion.
Pedological, sedimentological and geophysical studies at the colluvium and floodplain sediments as well as relict
field structures showed that in the last 2500 years there has been a considerable human impact on both water and
sediment budgets. This also had various implications on the further development of water courses, soils and relief.
Evidence for the development of flood plain sediments can be traced as far back as the late La Tène period, the
Roman Iron Age, and since the Middle Ages.
On one particular south-facing slope we found evidence of recultivation measures on a former quarry tailing heap
dating from the Middle Ages. This and other human construction activities and land uses lead to a significant
change in erosion and sedimentation patterns. It is surprising that sedimentation in flood plains was largely absent
during the Roman Iron Age despite intensive land use. Evidence shows that flash flood events with intensive accu-
mulation of soil matter in flood plains only occurred during the High Middle Ages. Sediments from the late Middle
ages and the Modern Times are largely missing.
The research undertaken in Segbach valley not only offers new insights into specific local historical land uses
and land use changes but also fundamental knowledge about the principles and impacts of long-term human-
environment interactions.
(CC BY 3.0)
http://www.aiac2018.de/
Coastal geoarchaeology in the Mediterranean – on the interdependence of landscape dynamics, harbour installations and economic prosperity in the littoral realm Organizers: Max Engel and Friederike Stock (University of Cologne) Mediterranean coastlines are highly dynamic geomorphic landscapes with lateral progradation of up to tens of kilometres in alluvial delta regions during the last 5000 years. After the significant deceleration of post-glacial eustatic sea-level rise around 7000-6000 years ago, a complex interplay of regional and local factors such as vertical tectonic movements, glacial isostatic rebound, sediment supply by rivers and coastal currents, deltaic compaction, and human intervention, led to locally different histories of coastal formation. As the coastal zone provided essential access to food, maritime commerce and colonisation activities, its dynamical nature had a significant impact on the prosperity of ancient communities. In fact, Mediterranean harbours as the gateways to the maritime realm were constantly threatened by gradual sedimentation, tectonic uplift or subsidence, as well as extreme events such as earthquakes or tsunamis. Many harbours became landlocked due to coastal progradation with fundamental repercussions on the political and economic status of ancient poleis. We invite any contributions studying the influence of the dynamic, physical coastal environment on human communities during Antiquity, may this influence be through gradual, long-term sedimentary or geomorphic processes, or episodic such as through earthquakes or tsunamis. We also invite contributions on any type of ancient human influence on the physical coastal environment including but not limited to the implementation of engineering measures or chemical or sedimentary imprints. All types of contributions are envisaged, including excavation-and field-based case studies, those comprising numerical models, synthesising reviews or advances in scientific methodology and techniques.