Understanding geomorphic responses to environmental change: a 19 000‐year case study from semi‐arid central Texas,USA

Understanding the impact of past climatic changes on landscape stability is crucial in order to predict and mitigate the effects of future changes. However, in arid and semi‐arid environments, reconstructions are often hampered by a poor understanding of the relationship between sediment deposition and climate. We present here data from central Texas, a region that is sensitive to environmental change but has received relatively little attention. The study integrates a chronology of 29 optically stimulated luminescence (OSL) ages from six sedimentary sites in a range of depositional contexts with a 19 000 a climate record derived from pollen extracted from the adjacent Boriack Bog. By comparing the two records, we aimed to assess the relationship between climate change and geomorphic activity. Data show that extensive aeolian and colluvial deposition occurred during the mid to late Holocene, with sedimentation generally increasing during more arid phases. However, a number of depositional events on slopes were associated with moister episodes, and sediment was also deposited in a summit setting immediately after phases of increased precipitation. Linkages between climate change and geomorphic response were therefore complex, being controlled by both sediment supply and transport energy. The climatic fluctuations identified in the Boriack Bog record highlight the sensitivity of central Texas to environmental change, while disparities in conditions recorded between it and other palaeoenvironmental sites in the southern USA emphasise the need for further work in order to enhance understanding of landscape sedimentary response to climate. Copyright © 2010 John Wiley & Sons, Ltd.     

Stable carbon isotope composition of terrestrial leaves: inter‐ and intraspecies variability,cellulose and whole‐leaf tissue difference,and potential for climate reconstruction

Stable carbon isotope analysis of terrestrial plant leaves preserved in Quaternary lake sediments has the potential to provide high‐resolution reconstructions of past climatic conditions. Preferably, δ¹³C measurements should be made on a single leaf component, e.g. cellulose, but this approach is often precluded by limited leaf availability. Previous work suggests that reliable palaeoclimatic information also may be derived from δ¹³C measurements on whole‐leaf tissue, given a similar degree of leaf decomposition between samples. Leaf δ¹³C data for 12 Scandinavian species of dwarf‐shrubs, shrubs and trees, and a comparison of δ¹³C data on recent and late Holocene Salix herbacea leaves, revealed that the δ¹³C signal registered by holocellulose is largely reflected by measurements on whole‐leaf tissue. Holocellulose was found to be consistently enriched in ¹³C, although this δ¹³C offset was smaller for subfossil leaves. This supports the use of δ¹³C measurements on whole‐leaf tissue for climate reconstruction, at least for leaves preserved in soft, late Holocene sediments with minimal diagenetic effects. Leaf carbon and nitrogen data on fresh leaves of the same 12 Scandinavian species, and corresponding data on late Holocene Salix herbacea leaves, suggest that the leaf C:N ratio is a suitable indicator of the degree of leaf decomposition. Copyright © 2003 John Wiley & Sons, Ltd.     

A high‐resolution multi‐proxy stalagmite record from Mechara,Southeastern Ethiopia: palaeohydrological implications for speleothem palaeoclimate reconstruction

An annually laminated stalagmite from Southeastern Ethiopia grew for 443±8 yr starting at 5023 yr BP (±160 yr) as determined by lamina‐tuned U‐Th dating. The speleothem shows three growth phases: (1) an initial phase where the stalagmite has a candlestick shape, deposited by relatively slow rate drip water; (2) a middle growth phase where laminae grow on the flanks, suggesting faster drip rates; and (3) a final growth phase where the speleothem becomes narrower owing to a decrease in drip water supply towards the end of deposition. Morphometry, annual growth rate, fluorescence index, and ²³⁴U/²³⁸U isotope ratio show marked differences between the growth phases, while δ¹³C and δ¹⁸O do not show significant variation, except within the third phase towards the top of the stalagmite, where they have higher values. The study indicates that the multiproxy approach is crucial as the different proxies respond to single climate forcing in different manners. Our results can be widely applied to speleothem studies distinguishing the relative importance of the various proxies in recording cave ‘external’ (climate, hydrology) and cave ‘internal’ (e.g. evaporation) processes. Copyright © 2006 John Wiley & Sons, Ltd.     

Effect of pedogenesis on the stable isotopic composition of calcretes and n‐alkanes: Implications for palaeoenvironmental reconstruction

In a fluvial system, depending on sub‐aerial exposure, non‐pedogenic pond calcretes can be modified into pedogenic calcretes. The present study attempts to understand the effect of sub‐aerial exposure and pedogenesis on calcretes using carbon and oxygen isotopic composition. For this purpose, two profiles (profile‐A and profile‐B) from the same stratigraphic level in Rayka from the western part of India were selected. The profiles are separated by a distance of 500 m and showed differences in calcrete characteristics. In profile‐A, the calcretes showed pedogenic features (root traces and void filling spar) whereas calcretes in profile‐B showed non‐pedogenic characteristics (fine laminations). However, some of the calcretes in profile‐A exhibited remnants of fine laminations suggesting that initially the calcretes had a non‐pedogenic origin but were modified due to pedogenesis. In profile‐A, the carbon and oxygen isotope values of pedogenic calcrete (δ¹³C_PC and δ¹⁸O_PC) showed more variation compared with non‐pedogenic pond calcretes (δ¹³C_SPC and δ¹⁸O_SPC) in profile‐B. The δ¹³C_PC and δ¹³C_SPC values exhibited a spread of 3·0‰ and 1·3‰, respectively, and δ¹⁸O_PC and δ¹⁸O_SPC values showed a spread of 2·3‰ and 1·3‰, respectively. The differences in the isotopic composition between the two profiles suggest that pedogenesis controlled the isotopic inheritance in calcretes. In addition, the carbon isotopic composition of organic matter (δ¹³C_OM) and n‐alkanes (δ¹³C_n‐alk) that forms the basis of palaeovegetational reconstruction have also been measured to understand the effect of pedogenesis on organic matter in both of the profiles. The average δ¹³C_OM values in profile‐A and profile‐B are ?23·4‰ and ?21·1‰, respectively. The disparity in δ¹³C_OM values is a result of the difference in the sources and preservation of organic matter. However, the δ¹³C_n‐alk values show a similar trend in profile‐A and profile‐B, indicating that sources of n‐alkanes are the same in both of the profiles and δ¹³C_n‐alk values are unaffected by the pedogenic modifications.     

Seasonal controls on sediment transport and deposition in Lake Ohau,South Island,New Zealand: Implications for a high‐resolution Holocene palaeoclimate reconstruction

Laminated sediments in Lake Ohau, Mackenzie Basin, New Zealand, offer a potential high‐resolution climate record for the past 17 kyr. Such records are particularly important due to the relative paucity of detailed palaeoclimate data from the Southern Hemisphere mid‐latitudes. This paper presents outcomes of a study of the sedimentation processes of this temperate lake setting. Hydrometeorological, limnological and sedimentological data were collected over a 14 month period between 2011 and 2013. These data indicate that seasonality in the hydrometeorological system in combination with internal lake dynamics drives a distinct seasonal pattern of sediment dispersal and deposition on a basin‐wide scale. Sedimentary layers that accumulate proximal to the lake inflow at the northern end of the lake form in response to discrete inflow events throughout the year and display an event stratigraphy. In contrast, seasonal change in the lake system controls accumulation of light (winter) and dark (summer) laminations at the distal end of the lake, resulting in the preservation of varves. This study documents the key processes influencing sediment deposition throughout Lake Ohau and provides fundamental data for generating a high‐resolution palaeoclimate record from this temperate lake.     

Recurrent spring‐fed rivers in a Middle to Late Pleistocene semi‐arid grassland: Implications for environments of early humans in the Lake Victoria Basin,Kenya

The effect of changing palaeoclimate and palaeoenvironment on human evolution during the Pleistocene is debated, but hampered by few East African records directly associated with archaeological sites prior to the Last Glacial Maximum. Middle to Late Pleistocene deposits on the shoreline of eastern Lake Victoria preserve abundant vertebrate fossils and Middle Stone Age arte‐facts associated with riverine tufas at the base of the deposits, which are ideal for palaeoenvironmental reconstructions. New data from tufas identified on Rusinga Island and on the mainland near Karungu, Kenya are provided from outcrop, thin sections, mineralogical, stable isotopic and U‐series dating analyses. Tufa is identified in four sites: Nyamita (94·0 ± 3·3 and 111·4 ± 4·2 ka); Kisaaka, Aringo (455 ± 45 ka); and Obware. The age ranges of these tufa deposits demonstrate that spring‐fed rivers were a recurrent, variably preserved feature on the Pleistocene landscape for ca 360 kyr. Poor sorting of clastic facies from all sites indicates flashy, ephemeral discharge, but these facies are commonly associated with barrage tufas, paludal environments with δ¹³C values of ca 10‰ indicative of C₃ plants and fossil Hippopotamus, all of which indicate a perennial water source. Other tufa deposits from Nyamita, Obware and Aringo have a mixed C₃/C₄ signature consistent with a semi‐arid C₄ grassland surrounding these spring‐fed rivers. The δ¹⁸O values of tufa from Nyamita are on average ca 1‰ more negative than calcite precipitated from modern rainfall in the region, suggesting greater contribution of depleted monsoonal input, similar to the Last Glacial Maximum. Microdebitage and surface‐collected artefacts indicate that early modern humans were utilizing these spring‐fed rivers. The presence of spring?fed rivers would have afforded animals a reliable water source, sustaining a diverse plant and animal community in an otherwise arid environment.     

中国黄土高原沉积物稳定碳同位素指标在古植被环境研究中的进展

重建古植被、古气候演化历史一直是地质学领域的研究热点,恢复晚新生代以来古植被环境变化不仅可以加深气候驱动机制的理解,而且可以更准确地预测未来气候变化趋势。黄土沉积中不同载体（如土壤总有机碳、次生碳酸盐、正构烷烃和黑碳等）的稳定碳同位素组成响应植被和气候变化,被广泛应用于古植被环境研究。然而,黄土沉积中不同碳同位素组成的影响因素复杂等又在一定程度上限制了指标的准确性及不同指标间的相互印证。分析中国黄土高原22个典型沉积剖面约2500个样品的总有机碳稳定碳同位素（δ¹³C_TOC）与磁化率数据表明,二者具有复杂的时间、空间特征。约100ka以来,绝大部分剖面δ¹³C_TOC与磁化率的相关性较好,指示夏季风强盛时C₄植物增多。但在更长时间尺度上,要充分考虑δ¹³C_TOC分馏和区域气候差异的影响。空间演化上,现代季风-非季风区分界线附近的剖面δ¹³C_TOC与磁化率的相关性极高（R²>0.7,p < 0.001）,可能指示该区域植被对季风强弱变化十分敏感。综合对比灵台、蓝田、白水等6个剖面的次生碳酸盐碳同位素记录（δ¹³C_PC）,将该指标用于黄土高原地区古植被比例重建时,首先要修正大气CO₂的影响,也可利用黄土序列δ¹³C_PC记录来进行重建古大气pCO₂等新的研究。目前,正构烷烃单体碳同位素（δ¹³C_n-alkanes）相关记录较少,研究发现该指标可较好地指示植被演化,渭南剖面的δ¹³C_n-alkanes记录呈现出与古温度、古降水等气候指标较好的一致性,但样品提取困难也阻碍了δ¹³C_n-alkanes的深入研究。黑碳稳定碳同位素（δ¹³C_BC）更多反映的是燃烧植被信息,在以草本和灌木植被类型为主的区域与δ¹³C_TOC记录更为一致,可以较为准确地指示生长植被类型的变化。

     

Sr isotope excursion across the Precambrian–Cambrian boundary in the Three Gorges area, South China

The Precambrian/Cambrian (PC/C) boundary is one of the most important intervals for the evolution of life. However, the scarcity of well-preserved outcrops across the boundary leaves an obstacle in decoding surface environmental changes and patterns of biological evolution.In south China, strata through the PC/C boundary are almost continuously exposed and contain many fossils, suitable for study of environmental and biological change across the PC/C boundary. We undertook deep drilling at four sites in the Three Gorges area to obtain continuous and fresh samples without surface alteration and oxidation. ⁸⁷Sr/⁸⁶Sr ratios of the fresh carbonate rocks, selected based on microscopic observation and geochemical signatures of Mn/Sr and Rb/Sr ratios, aluminum and silica contents, and δ¹³C and δ¹⁸O values, were measured with multiple collector-inductively coupled plasma–mass spectrometric techniques.The chemostratigraphy of ⁸⁷Sr/⁸⁶Sr ratios of the drilled samples displays a smooth curve and a large positive anomaly just below the PC/C boundary between the upper part of Baimatuo Member of the Dengying Formation and the lower part of the Yanjiahe Formation. The combination of chemostratigraphies of δ¹³C and ⁸⁷Sr/⁸⁶Sr indicates that the ⁸⁷Sr/⁸⁶Sr excursions preceded the δ¹³C negative excursion, and suggests that global regression or formation of the Gondwana supercontinent, possibly together with a high atmospheric pCO₂, caused biological depression.     

Palaeoenvironmental and diagenetic reconstruction of a closed‐lacustrine carbonate system – the challenging marginal setting of the Miocene Ries Crater Lake (Germany)

Chemostratigraphic studies on lacustrine sedimentary sequences provide essential insights on past cyclic climatic events, on their repetition and prediction through time. Diagenetic overprint of primary features often hinders the use of such studies for palaeoenvironmental reconstruction. Here the potential of integrated geochemical and petrographic methods is evaluated to record freshwater to saline oscillations within the ancient marginal lacustrine carbonates of the Miocene Ries Crater Lake (Germany). This area is critical because it represents the transition from shoreline to proximal domains of a hydrologically closed system, affected by recurrent emergent events, representing the boundaries of successive sedimentary cycles. Chemostratigraphy targets shifts related to subaerial exposure and/or climatic fluctuations. Methods combine facies changes with δ ¹³C–δ ¹⁸O chemostratigraphy from matrix carbonates across five closely spaced, temporally equivalent stratigraphic sections. Isotope composition of ostracod shells, gastropods and cements is provided for comparison. Cathodoluminescence and back‐scatter electron microscopy were performed to discriminate primary (syn‐)depositional, from secondary diagenetic features. Meteoric diagenesis is expressed by substantial early dissolution and dark blue luminescent sparry cements carrying negative δ ¹³C and δ ¹⁸O. Sedimentary cycles are not correlated by isotope chemostratigraphy. Both matrix δ ¹³C and δ ¹⁸O range from ca −7·5 to +4·0‰ and show clear positive covariance (R  = 0·97) whose nature differs from that of previous basin‐oriented studies on the lake: negative values are here unconnected to original freshwater lacustrine conditions but reflect extensive meteoric diagenesis, while positive values probably represent primary saline lake water chemistry. Noisy geochemical curves relate to heterogeneities in (primary) porosity, resulting in selective carbonate diagenesis. This study exemplifies that ancient lacustrine carbonates, despite extensive meteoric weathering, are able to retain key information for both palaeoenvironmental reconstruction and the understanding of diagenetic processes in relation to those primary conditions. Also, it emphasizes the limitation of chemostratigraphy in fossil carbonates, and specifically in settings that are sensitive for the preservation of primary environmental signals, such as lake margins prone to meteoric diagenesis.     

Topographically‐independent ice flow in northwestern British Columbia: implications for Cordilleran Ice Sheet reconstruction

Studies in southern British Columbia have shown that Cordilleran Ice Sheet flow was controlled by topograph, even in full glacial time. New ice‐flow evidence from the Nass River region, northern British Columbia, however, indicates that ice was thicker there and that the continental ice‐sheet phase of glaciation was reached. Inspection of high elevation sites has revealed a suite of ice‐flow indicators (mainly striae) undetected by earlier work. These suggest that at the Last Glacial Maximum (Fraser Glaciation), ice flowed southwestward across the Nass River region from an ice divide that probably was located in the Skeena Mountain area. Comparisons with adjacent work allow this divide to be mapped over a wide area. The results suggest that maximum ice thicknesses in the northern part of the Cordilleran Ice Sheet were larger than reported previously. The location of storm tracks in full glacial time may have played an important role in the production of an ice sheet that was thicker in northern British Columbia than it was in the southern half of the province. During deglaciation, ice thinned and gradually became confined to fiords and valleys, resulting in numerous and variable ice‐flow directions at that time. Topographic control was thus exerted on ice flow only after the glacial maximum was reached, despite the significant amount of relief in this region. Copyright © 2002 John Wiley & Sons, Ltd.     

Sequential and climatic framework of the growth and demise of a carbonate platform: implications for the peritidal cycles (Late Jurassic,North‐eastern France)

The Middle Oxfordian of the eastern Paris Basin constitutes a remarkable example of the growth and demise of a carbonate platform. Fischer plots, sedimentary and diagenetic features allow the identification of four depositional cycles (S5 to S8) in the Transversarium Zone; they are inserted in a lower frequency cycle of increased/decreased accommodation space (SoIII). The long‐term period of accommodation creation occurred during the older S5 and S6 cycles, the maximum accommodation zone being located in the lower part of the S6 cycle. This high accommodation period was tectonically controlled and was coeval with local distensive activity of a Hercynian fault. A major minimum accommodation zone exists during the S8 cycle. At that time, the platform was isolated and presented both a windward and a leeward margin. The growth of the platform was favoured by a warm and arid climate, oligotrophic conditions and reduced siliciclastic input during a highstand in relative sea‐level. These palaeoenvironmental features favoured the proliferation of phototrophic organisms producing carbonate material. The death of the platform was generated by a reduction in the carbonate production surface during a lowstand in relative sea‐level and by the appearance of mesotrophic conditions induced by the increase in siliciclastic inputs at the beginning of a period with a cooler and more humid climate. In the eastern Paris Basin, during the Middle Oxfordian, the parasequences are ordered and present ‘greenhouse’ characteristics. In contrast, at the beginning of the S8 cycle, the randomness in the thickness of contiguous parasequences increased. Decreased carbonate production during the lowstand caused by a transition from photozoan to heterozoan benthic communities certainly favoured this randomness and the appearance of catch‐down parasequences.     

The δ18O stratigraphy of the Hoxnian lacustrine sequence at Marks Tey,Essex, UK: implications for the climatic structure of MIS 11 in Britain

Marine Isotope Stage 11 (MIS 11) is considered one of the best analogues for the Holocene. In the UK the long lacustrine sequence at Marks Tey, Essex, spans the entirety of the Hoxnian interglacial, the British correlative of MIS 11c. We present multiproxy evidence from a new 18.5‐m core from this sequence. Lithostratigraphy, pollen stratigraphy and biomarker evidence indicate that these sediments span the pre‐, early and late temperate intervals of this interglacial as well as cold climate sediments that post‐date the Hoxnian. The δ¹⁸O signal of endogenic carbonate from this sequence produces several clear patterns that are interpreted as reflecting the climatic structure of the interglacial. As well as providing evidence for long‐term climate stability during the interglacial and a major post‐Hoxnian stadial/interstadial oscillation the δ¹⁸O signal provides strong evidence for abrupt cooling events during the interglacial itself. One of these isotopic events occurs in association with a short‐lived increase in non‐arboreal pollen (the NAP phase). The results presented here are discussed in the context of other MIS 11 records from Europe and the North Atlantic, particularly with respect to our understanding of the occurrence of abrupt climatic events in pre‐Holocene interglacials. Copyright © 2016 The Authors. Journal of Quaternary Science Published by John Wiley & Sons Ltd.     

Developing an algorithm for reconstruction blocky systems in discontinuous media: three‐dimensional analysis

Block detection is one of the important steps in all discontinuous methods of analysis such as discontinuous deformation analysis and discrete element method. It is in fact a pre‐processing step for these methods. This paper describes a new approach to the problem of geometrically defining polyhedral rock blocks created by the intersection of planar discontinuities in a rock mass. An approach is developed based on the concept of using matrices with integer elements that mostly represent vertices, edges, or face numbers and their connections. Using square matrices with integer elements and performing edge/face regularization reduce the size of the matrices because of elimination of unnecessary faces, edges, and vertices; speed and accuracy of block tracing operation will be increased. This algorithm is able to trace and identify all kinds of blocks including convex and concave blocks formed by limited or unlimited fractures. The simplicity of the procedure makes it very attractive. The algorithm was programmed in C#.Net by over 8100 code lines; several examples are presented to show application of the algorithm in different situations. Copyright © 2011 John Wiley & Sons, Ltd.     

Effective precipitation in southern Spain ( 266 to 46 ka) based on a speleothem stable carbon isotope record

We present the longest-duration directly dated terrestrial palaeoclimate record from the western Mediterranean region: a flowstone speleothem from Gitana Cave, southeast Spain. The main phase of growth was 274 to 58 ka, dated by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) U-series methods. Effective precipitation, which we consider primarily responsible for flowstone calcite δ¹³C variations, measured at 300 μm resolution, was higher during interglacials associated with marine oxygen isotope stages (MIS) 7 and 5, and lower during glacial MIS 6. There is a close correspondence between speleothem δ¹³C and sea surface temperature (SST) estimates from adjacent Atlantic Ocean cores during MIS 6, which implies that oceanic conditions are critical in controlling the western Mediterranean terrestrial moisture balance during glacial periods. Other features of our record, such as the sequence of termination II warming/moistening between approximately 133 and 127 ka, including a “pause” around 130–128 ka, and the lagged termination of MIS 5 warm intervals (5e, 5c and 5a) are similar to other terrestrial records within the Mediterranean basin, indicating climate synchroneity along the northern Mediterranean coast. The Gitana cave region also may have been a refugium for temperate species during short-lived cold/arid periods during MIS 5.     

Carbon isotope and rare earth element composition of Late Quaternary sediment gravity flow deposits on the mid shelf of East China Sea: Implications for provenance and origin of hybrid event beds

The East China Sea Shelf has an unusually wide and low gradient shelf, supplied from sediment‐charged rivers and large river delta systems, with bottom currents sweeping the sea floor and located in the path of strong typhoons. Sediment gravity flow deposits, including four hybrid event beds and a high density turbidite, are identified in a core from the mid‐shelf of the East China Sea. The hybrid event beds typically comprise three or two internal divisions from the base to the top: (i) H1, H3 and H5; or (ii) H3 and H5. Radiocarbon ages of the hybrid event beds were in the range of 3821 to 8526 yr bp . Based on correlation with surrounding cores, the hybrid events may have happened at any time between 1930 yr bp and 3890 yr bp . The δ¹³C values in hybrid event beds together with bathymetry data suggest local erosion on the shelf. The average δ¹³C value for the H1 division is similar to the H3 division in the hybrid event beds, implying that the organic matter in the H1 and H3 divisions may come from the same source area. Cross‐plots of upper continental crust normalized rare earth elements in the five units reveal that the sediment source of the four hybrid event beds and the turbidite was ultimately primarily from Korean rivers. Partial transformation from a moderate‐strength debris flow with the additional role of erosional bulking can explain occurrences of hybrid event beds on the East China Sea Shelf. The data indicate that hybrid sediment gravity flow deposits were sourced from intra‐shelf failures and subsequently transformed and deposited as hybrid event beds. The study shows that hybrid sediment gravity flows and turbidity currents may not necessarily indicate proximity to a major fluvial or deltaic system and that intra‐shelf sedimentation can be a sediment source. It is unlikely that the debris flows and turbidity currents were triggered by a hyperpycnal flow or tsunami, because both can carry continental and/or coastal signals which have not been recognized in the core. Typhoons are the probable triggering mechanism.     

Thickness and stable isotopic characteristics of modern seasonal climate-controlled sub-annual travertine laminas in a travertine-depositing stream at Baishuitai, SW China: implications for paleoclimate reconstruction

A continuous high-resolution (monthly) record of stable isotopes (δ¹³C and δ¹⁸O) in a well-laminated freshwater travertine deposited at Baishuitai, SW China from May 1998 to November 2001 was presented. The travertine exhibits clear annual bands with coupled brown/white color laminations. Throughout field investigation, it was found that the thin (1.5–2.2 mm), brown porous lamina was formed in the monsoonal rainy season from April to September, whereas the thick (5–8 mm), dense white lamina was formed in the dry season from October to March. The comparisons of lamina thickness and stable isotope signals in the travertine with the meteorological records allow us to constrain the relevant geochemical processes in the travertine formation under different climate conditions and to relate climate variables to their physicochemical proxies in the travertine record. Sympathetic variations in lamina thickness, δ¹³C and δ¹⁸O along the sampled profile reflect changes in hydrogeochemistry, showing that thin lamina and low δ¹³C and δ¹⁸O values occur in warm and rainy seasons. The decreased amount of calcite precipitation and low δ¹³C values during the warm and rainy seasons is caused by dilution of overland flow after rainfall. The low δ¹⁸O values are believed to be related to the rainfall amount effect in subtropical monsoonal regions. This process is thought to be markedly subdued whenever the amount of rainfall is lower than a given threshold. Accordingly, distinct minima in lamina thickness, δ¹³C and δ¹⁸O are interpreted to reflect events with above-average rainfall, possibly heavy floods, and vice versa. This study demonstrates the potential of freshwater travertine to provide valuable information on seasonal or even monthly rainfall variations.