Matthew D. Jones

A high-resolution late Holocene lake isotope record from Turkey and links to North Atlantic and monsoon climate

A high resolution proxy record of precipitation and evaporation variability through the past 1700 yr from δ18O analysis of a varved lake sequence from central Turkey shows rapid shifts between dry periods (AD 300–500 and AD 1400–1950) and wetter intervals (AD 560–750 and AD 1000–1350). Changes are consistent with changes in instrumental and proxy records of the Indian monsoon, dry summers in the Eastern Mediterranean being associated with periods of enhanced monsoon rainfall. In addition major shifts in the record are coherent with changes in North Atlantic winter climate with cold, wet periods in the Alps occurring at times of dry Turkish climate.

Climate variability over the last two millennia in the North American monsoon region, recorded in laminated lake sediments from Laguna de Juanacatlán, Mexico

High-resolution titanium (Ti) data obtained using an ITRAX XRF core scanner from a laminated sediment core from the Laguna de Juanacatlán, western central Mexico yield a unique high-resolution record of runoff (precipitation) change for the last 2000 years. In the absence of reliable, long-term meteorological records, comparison of the Ti data with information from the rich Spanish colonial period archives and the post-Independence period, confirms that Ti is a proxy for runoff. This interpretation is supported by comparison with other high-resolution archives from the surrounding region, primarily tree rings and other lake sediment sequences. The Juanacatlán Ti record is therefore a proxy for summer, monsoonal rainfall. The record provides new evidence from the Pacific margin of tropical North America of the occurrence of dry conditions through much of the Classic period (c. AD 300—900), and wetter conditions during the later Medieval period (c. AD 1200—1350). The period commonly known as the ‘Little Ice Age’ (LIA) shows considerable variability, with dry conditions in the early part (c. AD 1400—1600) and wetter conditions, punctuated by multiyear droughts through the eighteenth century. A notable feature of the record is the apparent decoupling of lacustrine sedimentation from the climate since the mid-twentieth century, possibly resulting from anthropogenic disturbance. Preliminary interpretations of the Ti record indicate that patterns are consistent with changes in monsoon strength associated with ENSO and solar forcing over the last two millennia.

Twenty Thousand-Year-Old Huts at a Hunter-Gatherer Settlement in Eastern Jordan

Ten thousand years before Neolithic farmers settled in permanent villages, hunter-gatherer groups of the Epipalaeolithic period (c. 22–11,600 cal BP) inhabited much of southwest Asia. The latest Epipalaeolithic phase (Natufian) is well-known for the appearance of stone-built houses, complex site organization, a sedentary lifestyle and social complexity—precursors for a Neolithic way of life. In contrast, pre-Natufian sites are much less well known and generally considered as campsites for small groups of seasonally-mobile hunter-gatherers. Work at the Early and Middle Epipalaeolithic aggregation site of Kharaneh IV in eastern Jordan highlights that some of these earlier sites were large aggregation base camps not unlike those of the Natufian and contributes to ongoing debates on their duration of occupation. Here we discuss the excavation of two 20,000-year-old hut structures at Kharaneh IV that pre-date the renowned stone houses of the Natufian. Exceptionally dense and extensive occupational deposits exhibit repeated habitation over prolonged periods, and contain structural remains associated with exotic and potentially symbolic caches of objects (shell, red ochre, and burnt horn cores) that indicate substantial settlement of the site pre-dating the Natufian and outside of the Natufian homeland as currently understood.

Olive cultivation in the heart of the Persian Achaemenid Empire: new insights into agricultural practices and environmental changes reflected in a late Holocene pollen record from Lake Parishan, SW Iran

Ancient Persia witnessed one of its most prosperous cultural and socio-economic periods between 550 bc and ad 651, with the successive domination of the Achaemenid, Seleucid, Parthian and Sassanian Empires. During this period agricultural activities increased on the Iranian plateau, as demonstrated by a remarkable arboricultural expansion. However, available data are not very informative about the spatial organization of agricultural practices. The possible links between climate conditions and agricultural activities during this millennium of continuous imperial domination are also unclear, due to the lack of parallel human-independent palaeoclimatic proxies. This study presents a new late Holocene pollen-based vegetation record from Lake Parishan, SW Iran. This record provides invaluable information regarding anthropogenic activities before, during and after the empires and sheds light on (i) spatial patterning in agricultural activities and (ii) possible climate impacts on agro-sylvo-pastoral practices during this period. Results of this study indicate that arboriculture was the most prominent form of agricultural activity in SW Iran especially during the Achaemenid, Seleucid and Parthian periods. Contrary to the information provided by some Greco-Roman written sources, the record from Lake Parishan shows that olive cultivation was practiced during Achaemenid and Seleucid times, when olive cultivation was significant, at least in this basin located close to the capital area of the Achaemenid Empire. In addition, pollen from aquatic vegetation suggests that the period of the latter centuries of the first millennium bc was characterized by a higher lake level, which might have favoured cultural and socio-economic prosperity.

Modifying the marsh: Evaluating Early Epipaleolithic hunter-gatherer impacts in the Azraq wetland, Jordan

The ecological impacts of human activities have infiltrated the whole of the ‘natural world’ and precipitated calls for a newly defined geological epoch – the Anthropocene. While scholars discuss tipping-points and scale, viewed over the longue durée, it is becoming clear that we have inherited the compounding consequences of a constructed environment with a long history of human landscape modification. By linking phytolith and micro-charcoal evidence from sediments in the Azraq Basin, Jordan, we discuss potential Early Epipaleolithic (23,000–17,400 cal. BP) human–environment interactions in this wetland. Our analyses reveal that during the Last Glacial Maximum, Levantine hunter-gatherers could have had a noticeable and increasing impact on their environment. However, further work needs to be undertaken to assess the range, frequency, intensity, and intentionality of marsh disturbance events. We suggest that the origin of ‘persistent places’ and larger aggregation settlements in the Azraq Basin may have been, in part, facilitated by human–environment interactions in the Early Epipaleolithic that consequently enhanced the economic and, subsequently, social meaning of that landscape. Through their exploitation of the sensitive wetland environment, hunter-gatherers were modifying the marshes and initiating long-term changes to the already dynamic and changing landscape at the close of the Pleistocene. These findings challenge us to further reconsider the way we see early hunter-gatherers in the prehistory of the Levant and in the development of the ‘Anthropocene’.

Spatial patterns in the oxygen isotope composition of daily rainfall in the British Isles

AbstractnUnderstanding the modern day relationship between climate and the oxygen isotopic composition of precipitation (δ18OP) is crucial for obtaining rigorous palaeoclimate reconstructions from a variety of archives. To date, the majority of empirical studies into the meteorological controls over δ18OP rely upon daily, event scale, or monthly time series from individual locations, resulting in uncertainties concerning the representativeness of statistical models and the mechanisms behind those relationships. Here, we take an alternative approach by analysing daily patterns in δ18OP from multiple stations across the British Isles (nxa0=xa010–70 stations). We use these data to examine the spatial and seasonal heterogeneity of regression statistics between δ18OP and common predictors (temperature, precipitation amount and the North Atlantic Oscillation index; NAO). Temperature and NAO are poor predictors of daily δ18OP in the British Isles, exhibiting weak and/or inconsistent effects both spatially and between seasons. By contrast δ18OP and rainfall amount consistently correlate at most locations, and for all months analysed, with spatial and temporal variability in the regression coefficients. The maps also allow comparison with daily synoptic weather types, and suggest characteristic δ18OP patterns, particularly associated with Cylonic Lamb Weather Types. Mapping daily δ18OP across the British Isles therefore provides a more coherent picture of the patterns in δ18OP, which will ultimately lead to a better understanding of the climatic controls. These observations are another step forward towards developing a more detailed, mechanistic framework for interpreting stable isotopes in rainfall as a palaeoclimate and hydrological tracer.