Geoarchaeology has become a very important field of study, by using the techniques of Geosciences in combination with archaeological research to discover and understand more about human prehistory (Waters, 1992). Geoarchaeology is an important field of study in the Arabian Gulf region and continues to improve the interpretation of human prehistory and the impacts humans have had on the Holocene landscape. Combining Geoscience techniques with climate proxy data and archaeological research, significant discoveries can be made about the effects humans have made upon the landscape.
Wilkinson (2005) has used geoarchaeological techniques to try and explain valley fill sequences and the causes of deposition within them. By using records of environmental change from ocean cores and lacustrine records in combination with geoarchaeological sequences and records of settlement and land use, a record can be produced of human effects upon the environment. Similar work has been done in other parts of the world by Sageidet (2009) in Norway using evidence from pollen analysis and soil micromorphology to reconstruct Holocene human land use. French et al (2009) used pollen, charcoal, micromorphological, and radiocarbon analyses to look at the signatures of fires and how these effected vegetation growth in the Rio Peurco river channel in New Mexico. In Japan, geoarchaeological studies were carried by Izuho et al (2009) looking at the stratigraphy, geochronology, depositional environments and post-depositional disturbances at a site to better understand human behaviour and its relationship with the environment. Other similar geoarchaeological studies have been conducted by Hill et al (2008) in North America and Hesse and Baade (2009) in Southern Peru.
From using lacustrine sequences from lakes and Paleosols from Yemen, Wilkinson (2005) has shown that the climate became drier from about 6000 cal yr B.P and that human settlement increased within the last 4000 years in the area. The heightened effect of increased human settlement and climatic drying are what is thought to be the cause for valley fills found in both Southern Arabia and The Northern Fertile crescent.
Geoarchaeological work conducted in the area is also summarised by Wilkinson (1999) in Northern Syria, Northern Iraq and Southern Turkey using lake climate proxy data and gathering the moisture index from oxygen isotope and Ca, Mg and Sr and then using the geoarchaeological evidence from valley fills and settlement evidence to discuss landscape change. It was found that settlement nucleation and population growth were occurring as conditions in the area became drier. Due to this there were increases in the loss of vegetation. By humans creating this loss of vegetation it exposes vulnerable soil and increases erosion. The bare soil will also enhance surface run-off at which Wilkinson (1999) states made rivers became more 'flashy'. This is thought to be because there was an increase in overland flow on tracks and animal trails which were increasing flood peaks and exacerbating soil erosion.
Morozova (2005) has looked at how avulsions of the Euphrates and Tigris rivers could have been effected by human occupation in Lower Mesopotamia. Avulsions are an abandonment of a river channel to form a new channel in a different location. During the early Holocene the area of the Tigris-Euphrates delta was mostly populated by farming communities. The civilisation there was famously known for irrigation agriculture, flood-control systems and having the worlds first cities. Their impact on the landscape and environment around them was enormous. Techniques used concerning the avulsions came from Holocene stratigraphy and deposits from the rivers' plains and from previous archaeological and geomorphological surveys. It is suggested that intake points for irrigation water could be sites where avulsions are more likely to be triggered. It is also speculated there were channel diversions to control river flow to downstream cities and construction of walls and levee's to prevent avulsions (Morozova, 2005). These practises which could either change the rivers natural flow or attempts to stabilise it have changed the landscape of the area. The effects are still being studied in further detail with geoarchaeological techniques being highly useful in conjunction with archaeological research.
Roberts (1990) has been able to provide some details of human-induced landscape change in Southern Turkey. By constructing a pollen analysis this has allowed a record of vegetation change to be produced and has shown there has been some significant woodland clearance phases during the Holocene. Using other archaeological research which states how populated human settlements were in the area at different times and comparing this with how abundant vegetation was at the time, from this a pattern can be viewed. Where there is increasing densities of human settlement there have been large decreases in vegetation. As vegetation cover decreases a marked decrease in human settlement populations can be seen. There has also been a general increase in soil erosion as a result of increased human activity in the area.
Wilkinson (1997) conducted geoarchaeological work in Yemen using pedostratigraphy and Holocene sedimentary sequences. By using these, information about sedimentation in Highland Yemen could be gathered and the degree to which it is effected by both climatic and human influences. The sedimentary sequences are up to 12m in depth which can be up to 20,000 years old. The type of information that can be gathered from them includes variations in vegetation cover, climatic change, the development of communities and construction of terraced fields. Findings from the study were that humans had a significant impact upon sedimentation. Which included the possibility that they cleared vegetation from slopes to make way for the construction of field terraces. Also overgrazing by livestock would be likely to lead to significant degradation of grass cover. Although terrace construction is likely to initially increase erosion and decrease slope stability from vegetation loss it is thought it will ultimately lead to increases in slope stability and decreased erosion. Although Wilkinson (1997) states that the increased need for terracing is a reflection of population growth because of the need for increased food production, so erosion for the entire area is likely to be increasing from agricultural practises. Whether field terraces lead to decreased erosion or not, it still had a significant effect on the landscape and influence of the sedimentation found in Yemen in the face of an increasingly drying climate.
Further geoarchaeological study has been conducted for the lower Gulf region in Southwestern Arabia by Parker et al (2006). This area is highly significant and has had human settlement since at least 8000 cal BP with humans utilising its unique access to both marine and agricultural resources (Parker et al, 2006). Evidence was gathered from palaeolake sediments which were subjected to mineral magnetic susceptibility tests which are used to establish when wet and dry conditions occurred. During wet conditions there is a high amount of vegetation cover, this occurs when there is low mineral magnetic values. High mineral magnetic values would be associated with periods of aridity, vegetation loss and consequently landscape instability. This inforamation can be used to create a record of climate and environmental change during the Holocene. Other geoarchaeological research in the same region has included making a record of vegetation history. Parker et al (2004) produced a phytolith, pollen and carbon isotope record to show what vegetation occurred at different stages during the Holocene. This research improves environmental and climate knowledge of the region which can be used in conjunction with other archaeological studies to further understand human impacts in the Arabian Peninsula during the Holocene.
To conclude, geoarchaeology is used around the world as an approach to find out more about human history and its relationship with the environment. Various different techniques are used from geosciences in collaboration with climate proxies and archaeological research. These were successfully used in Northern Syria to find out more about how rivers were becoming more 'flashy' as humans negative impacts on the environment were leading to loss of vegetation and consequent soil erosion. Similar findings occurred in Southern Turkey as pollen records were used to map changes in vegetation which when compared with archaeological research found that loss of vegetation increased as human population and nucleation increased in the area. Studying river avulsions was used in the Lower Mesopotamia region as the effects of irrigation and flood control are found to be a possible cause for effecting river courses in the region. Research in Yemen using pedostratigraphy and Holocene sedimentary sequences allowed insights into what effects farming practises and terrace construction were having in the area. Which found that erosion was increasing as the need for higher food production increased but terrace construction was likely to be lessening the negative erosion problems. Extensive geoarchaeological research in Southern Arabia produced important environmental information which could be used for researching the society-environment relationship. All these areas in the Arabian Gulf have benefited from geoarchaeological research which has helped to contribute to the understanding of past human impacts on the Holocene landscape.
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