Al Gharbia Palaeoenvironmental Report
U21147 – Assignment 2
Data analysis exercise (50%)
For the second assignment you need to analyse the geoarchaeology data set from Al Gharbia, UAE, which you have all generated from the lab classes. You have all generated an AMAZING data set. Your task is to write a short-rapid communication for a scientific journal paper (Journal of Archaeological Science).
The Title, Key Words, Introduction, Study Site and Methods have already been written (see below). You need to write the Results, Discussion, Conclusions and References for the paper.
Tips:
- In essence you are writing the Results and Discussion section of a scientific journal paper. This should be based on the format used by Journal of Archaeological Science.You have a maximum word limit of 2000 words to complete the exercise.
- You MUST use the following headings in your work
- Results – describe the data and values in each zone. The number of zones you use is up to you.
- Discussion – you need to discuss your results and compare them with other work that has been conducted from across the region. Several papers are also included in the Assignment 2 folder. TOP TIP – look at the results and discussion sections from these papers to get an idea of how you should present your work.
- Conclusions – a brief overview of the key findings
- References – ensure that you use the correct style of referencing (Harvard) both in the main body of the text and in the list of references.
Think carefully about what each geoproxy is showing you e.g. what does LOI 550°C % actually show you? What do changes in the direction of the curves (troughs or peaks) mean? Arid vs Wet? Stable vs Unstable landscape? Deep lake/Sallow lake/dry lake? How do these changes relate to climate and human occupation of the landscape? Are these periods of demographic expansions or contraction for human populations?
And finally……..make sure you spend some time completing this exercise. It will not be possible to complete the exercise the ‘night before’. Read the papers provided on the VLE and any others that you may find via the Library or Google Scholar. Before writing the Discussion make sure you are familiar with the following: (a) the climate of the region from10,000 to 6000 cal BP; (b) the Neolithic archaeology.
Title
A geoarchaeological and palaeoenvironmetal record from Al Gharbiapalaeolake, United Arab Emirates
Keywords: geoarchaeology, Arabia, climate change, Holocene, human demographics
1.0 Introduction
Southeast Arabia is uniquely positioned with respect to both archaeological and palaeoclimatic studies. Its position at the interface of the two of the worlds most dynamic atmospheric systems: the Indian Ocean Summer Monsoon (IOSM) and the Mid-Latitude Westerlies (MLW), has meant that during the early-mid Holocene, the regionexperienced dramatic changes in both climate and landscape (Parker et al., 2004; 2006a; 2006b; Preston et al., 2012; 2015). Abrupt shifts between pluvial phases and periods of increased aridity induced significant changes in both flora and fauna, whilst periodic eustatic sea level changes led to the formation of significant coastal and inland sabkha. In addition, regional climatic changes likely also had a significant impact on human populations within the region at this time (Preston et al., 2012; 2013; 2015). In adjacent regions such as the Sahara, similar abrupt humid-arid transitions in hydroclimatic conditions have been suggested as causal agents of societal change (e.g. Brooks, 2006; Tierney and DeMenocal, 2013), exemplifying the importance of palaeoenvironmental records from low latitude desert regions in understanding early techno-cultural trajectories.
Following the onset of deglaciation that marked the transition to the current Holocene period, widespread humidity occurred across the Saharo-Arabia desert belt. This change was initiated by a northward displacement in the mean latitudinal position of the Intertropical Convergence Zone (ITCZ), which caused rainfall associated with the African and Indian Ocean Monsoon systems to intensify and shift north of their current position. The concurrent activation of hydrological systems led to the development of active drainage systems and lake formation in previously arid-hyperarid regions, along with the widespread development of vegetation. Palaeoenvironmental records from lake deposits (e.g. McClure, 1976; Schulz & Witney, 1986; Lezineet al., 1998, 2007; Radies, 2005; Parker et al., 2004, 2006; Davies, 2006; Rosenberg et al., 2011; Preston et al., 2012; 2015) and speleothems (e.g. Burns et al., 1998; Fleitmann et al., 2002, 2007; Fleitmann and Matter, 2009)confirm the extent of environmental amelioration during the Early Holocene Humid Period, and highlight the extent of increased freshwater availabilityat this time.
These archives have proved invaluable in establishing the extent of environmental change during the early Holocene; however, the spatio-temporal variability of humidity increases remains poorly defined. While records from southern regions of Arabia (e.g. Radies et al., 2005; Davies, 2006; Fleitmann, 2007; Lézine et al., 2010; Berger et al., 2012) indicate that the onset of humidity commenced between ca. 11-10 ka BP, lacustrine records from southeastern regions (e.g. Parker et al., 2006a; Preston et al., 2015) suggest a later transition to wet conditions at ca. 9 ka BP. In the southern Nefud, early Holocene lake formation is generally believed to have commenced between ca. 10-9 ka BP (Whitney and Getings, 1982; Whitney, 1983; Whitney et al., 1983; Engel et al., 2012; Crassard et al., 2013; Dinies et al., 2015). Such findings generally support the hypothesis that the monsoon rain belts took at least 1,000 years to track northwards across Arabia (sensu, Parker, 2009). Recently, however, findings from the Jubbah basin in the southern Nefud have shown that lake formation may have occurred as early as ca. 12 ka BP (Hilbert et al., 2014). Such apparent temporal inconsistencies not only highlight the variability in the progression of rainfall systems, but also indicate that the activation of hydrological systems in some regions may occur independently as a result of unique geomorphic parameters. In addition, the potential contribution of other rainfall systems to Arabia during the early Holocene remains unclear. Evidence from speleothem records (Fleitmann et al., 2007) suggests that westerly convection, an important source of moisture throughout northern and central regions today, became increasingly important from ca. 6.3 ka BP.
A number of records also indicate that early-mid Holocene humidity was punctuated by a series of abrupt arid events. Abrupt arid phases marked by an influx of minerogenic material and loss of local vegetation cover are reported from the UAE at palaeolake Wahalah at ca. 8.0 ka, 6.9-6.7 ka, ca. 6.4 ka and ca. 6.1 ka BP, and palaeolake Awafi at ca.8.0-7.8 ka, ca. 7.5-7.2 ka, and 6.5-6.2 ka BP (Preston et al., 2012; 2015). While a precise chronology for these events is presently absent, it is significant that speleothem records from Oman (Fleitmann et al., 2007) also record abrupt reductions in rainfall at ca. 8.2-8.0 ka, ca. 7.5-7.2
