Abstract It is generally accepted that the clay mineralogy of the shale formation is a primary causative factor of shale instability. This review considers a scenario of shale instability relating to illitic minerals. From the literature the thickness of the double electric layer (DEL) of the aqueous solutions associated with the charged external surfaces of clay minerals is of the same order or even thicker than the sizes of a significant proportion of the pores found in shales. In these circumstances, overlap of the DELs associated with the exposed outer surfaces of clay minerals on opposing sides of slit-like micropores (<2 nm in diameter) and mesopores (2–50 nm in diameter) in a lithostatically compressed shale would bring about electrostatic repulsion and lead to increased pore/hydration pressure in illitic shales. In shales and sandstones, illitic material is usually described in terms of two different phases, namely illite per se and mixed-layer illite–smectite (I/S). Evidence is presented to show that it is often the case that only one illite phase exists and that in reality the mixed-layer I/S is simply very thin illite (<5 nm in thickness) in the early stages of its growth. Such material is of common occurrence in the unconventional hydrocarbon reservoirs of the USA.

Abstract The Arbuckle Group of the midcontinent comprises the mid-southern part of the great American carbonate bank (GACB) and consists mostly of carbonates with a few laterally consistent sandstones. The Arbuckle Group is found in the Anadarko, Ardmore, and Arkoma Basins and surrounding environs in the Texas panhandle, Oklahoma, and Arkansas. These basins represented a significant downwarp associated with early rifting in the area now located in the southern one half of both the states of Oklahoma and Arkansas. Similar to other parts of the GACB, the thick widespread Cambrian–Ordovician Arbuckle Group was deposited as mostly restricted shallow-water marine carbonates. The Arbuckle is a cyclic carbonate dominated by intertidal and shallow subtidal facies. In some areas, supratidal or deeper subtidal facies are observed. The depositional model is represented byan extensive, dominantly regressive, tidal flat with persistent peritidal facies across much of the GACB. These peritidal cycles shallow upward with significant variation in thickness from as thin as 4 ft (1.2 m) to more than 110 ft (>33.5 m) thick. Large-scale regional changes in relative sea level may have had a large influence on the type of cycles and sequences that formed during Arbuckle deposition. Arbuckle strata, especially within third-order sequence boundaries, are correlatable across the basin. Within the sequence boundaries, cycles can be further grouped into packages of sequences that are composed mostly of either intertidally or subtidally dominated cycles. Detailed local to regional correlation of the facies bundles can be made with gamma-ray and resistivity logs; however, facies are commonly obscured by a strong diagenetic overprint that makes detailed correlation difficult. Reservoirs in the Arbuckle are complex, and porosity is controlled by original depositional fabric, diagenesis, paleokarst, and fracture overprint. Upper subtidal and lower intertidal facies typically have the depositional fabric most conducive to reservoir development. Dia-genetic changes are a continuum that begins with early diagenesis, including hypersaline or evaporative conditions as well as vadose and phreatic conditions, and followed by deep phreatic to late thermal diagenesis. Evidence that porosity formed during multiple diagenetic phases exists. Dolomitization and precipitation events are also evidenced at various levels of the profile. Dolomite is the most abundant mineral and can be subdivided into early (syn-genetic to penecontemporaneous) hypersaline dolomite, shallow burial mixed-water (phreatic) dolomite, and deeper burial to thermal (baroque and xenotopic) dolomite. The super-Sauk unconformity is recognized as evidence of a eustatic sea level drop and has been used to mark the boundary between the Sauk and Tippecanoe depositional mega-sequences. The Arbuckle Group contains multiple unconformities at major sequence boundaries. Paleokarst is especially prevalent beneath the super-Sauk unconformity, especially along major sequence boundaries with related unconformity surfaces. Paleokarstic features in the Arbuckle Group have been identified in outcrop in the Arbuckle Mountains of southern Oklahoma and in the southern Ozark uplift in northeastern Oklahoma. Numerous cores and logs indicate collapse breccias that are interpreted to have formed in response to karst conditions. The Arbuckle Group is an important petroleum reservoir in the midcontinent, and has great potential especially for natural gas. Exploration is enhanced by understanding the complex relationships of depositional processes, stratigraphic relationships, paragenesis, and structural overprints. Reservoir development is typically along sequence boundaries, especially where facies have strong diagenetic overprints from dolomitization and dissolution associated with paleokarstic events. No major source rocks exist below or within the Arbuckle Group, so the best reservoirs are structurally related with strong fracture overprints and juxtaposed with source rocks or are along migration pathways.

Abstract Specialists and the general public alike are very aware of human impacts on our environment. Climate change, deforestation, desertification, soil erosion and other topics are currently much in the news, but human influence on the environment is not a new phenomenon. Geoarchaeologists study the traces of human interactions with the geosphere dating back to ancient times, as well as up to and in the present. Geoarchaeological investigations provide the key to recognizing landscape and environmental change within a region, as well as reconstructing ancient landscapes and palaeoclimatic regimes. Such an interdisciplinary approach makes it possible to interpret the ways that humans affect the geosphere, through such things as subsistence and resource exploitation activities, settlement location, and local and regional land-use patterns. This approach also allows us to determine the effects of environmental change on human societies. For millennia, humans have been coping with, or provoking, environmental change. We have exploited, extracted, over-used but also in many cases nurtured the resources that the geosphere offers. In the geoarchaeological perspective, human life has never been separate from nature. Geoarchaeology can thus provide a more inclusive and longer-term view of human–geosphere interactions, and serve as a valuable aid to those who try to determine sustainable policies for the future.

Abstract Intensive agricultural development of the forest zone of the East European Plain started in the second part of the first millennium AD. Although the majority of the mediaeval population were peasants, archaeological study of ancient rural settlements is much less developed than that of ancient towns. The analysis of interrelationships between environmental conditions and the agricultural pattern across space, including the corresponding pattern of rural settlements, helps us to delimit the spatial frame in which it is possible to find rural settlements of different historical epochs, even if they have since disappeared. Five areas with different historical types of agricultural landscapes were revealed, based on their geological and climatic characteristics. Another analysis essential for archaeology deals with the age of contemporary agricultural landscapes and rural settlements along with the factors and laws that control their changes through time and space.

Abstract Coastal areas have been prime locations for habitation and commerce. Early authors such as Pausanias (second century CE), and Strabo (64 or 63 BCE–24 CE) noted the impacts of shoreline changes. Geomorphological and subsurface geological data, combined with archaeological excavation and ancient texts, indicate a long interplay between natural processes of estuarine infilling by sediments from the Küçük Menderes River (ancient Cayster River) and multiple attempts of human intervention to preserve the harbours of Ephesus. Strabo noted that harbour engineering efforts there, such as the construction of a mole to prevent siltation, instead created a sediment trap that made things worse. The pre-Holocene river valley was inundated by Holocene sea-level rise that formed the ancient Gulf of Ephesus. Extensive palaeogeographical studies, based on sediment coring, geomorphology, archaeology and history, have provided details of the problems the inhabitants faced in keeping vital harbours in operation. Dating and analysis of sedimentary deposits has allowed the description of shifting river courses, floodplain changes, human intervention, and anthropogenic deposits at Ephesus. During and following Classical times sediment deposition rapidly began to fill in the embayment, requiring the inhabitants to regularly shift the harbours westward. Ultimately, it was to no avail.

Abstract Our study area is located in northwestern Argentina. It is a semiarid valley in which developed agricultural pre-Columbian settlements were located. The objectives of our research were to establish the geomorphological characteristics of the area, its relative chronological development, and the relationships between geomorphological development and pre-Columbian settlements. Pre-Quaternary lithologies are represented by a metamorphic basement that is commonly exposed on slopes and belongs to the Precambrian and Cambrian periods. Tertiary sediments from several formations are exposed over an extensive surface forming cuesta relief landforms. Quaternary landscape units were classified according to their genesis into structural–denudational landforms (denudational slopes and structural scarps), denudational landforms (covered glacis), fluvio-alluvial landforms (alluvial fans, fluvial fans, and fluvial terraces) and aeolian forms (stabilized dunes). Archaeological sites belonging to the Formative (500 BC–AD 1000) and Regional Development (AD 1000–1500) periods were identified. The main archaeological sites are located on the surfaces of debris-flow deposits and some covered glacis. They are characterized by the presence of residential units together with agricultural structures (terraces and irrigation channels). The earlier settlements (Formative period) are restricted to alluvial fan landforms (debris-flow deposits), where present hydrological supply is lower than in the rest of the study area. Later settlements (Regional Development period) are juxtaposed with earlier settlements in the south of the area, where present hydrological supply is higher owing to larger river catchments and moisture-laden winds from the SE.

Abstract Tepe Pardis, a significant Neolithic–Chalcolithic site on the Tehran Plain in Iran, is, like many sites in the area, under threat from development. The site contains detailed evidence of (1) the Neolithic–Chalcolithic transition, (2) an Iron Age cemetery and (3) how the inhabitants adapted to an unstable fan environment through resource exploitation (of clay deposits for relatively large-scale ceramic production by c . 5000 BC, and importantly, possible cutting of artificial water channels). Given this significance, models have been produced to better understand settlement distribution and change in the region. However, these models must be tied into a greater understanding of the impact of the geosphere on human development over this period. Forming part of a larger project focusing on the transformation of simple, egalitarian Neolithic communities into more hierarchical Chalcolithic ones, the site has become the focus of a multidisciplinary project to address this issue. Through the combined use of sedimentary and limited pollen analysis, radiocarbon and optically stimulated luminescence dating (the application of the last still rare in Iran), a greater understanding of the impact of alluvial fan development on human settlement through alluviation and the development of river channel sequences is possible. Notably, the findings presented here suggest that artificial irrigation was occurring at the site as early as 6.7±0.4 ka (4300–5100 BC).

Abstract In 2002 and 2004–2005 archaeological investigations were undertaken on middens exposed by coastal erosion at West Voe in the south of Mainland Shetland, UK. This work established that the site dated from c . 4000 cal BC to c . 3250 cal BC and was of major importance for two reasons: (1) as the first of Mesolithic date to be found on Shetland; (2) as the first site to be found in the Northern Isles that spanned the Mesolithic–Neolithic transition. This paper describes investigations into the origin of sands deposited around 3500 cal BC and their potential effect on human settlement. The sands in question lie between two midden deposits, the lower of which accumulated over the period 4000–3500 cal BC and the upper 3500–3250 cal BC. The sands, therefore, dated to the period shortly after the adoption of agriculture on the archipelago, represented in the lower midden by the appearance of domesticated species and ceramics at around 3700–3600 cal BC, and represented a disruption in human occupation at a critical point in the development of a changing use of the landscape.

Abstract Measurements of δ 13 C and δ 18 O values of the riverine tufa samples dated by the accelerating mass spectrometry- 14 C method have been used for discussion of land-cover change in the catchment area of the Xiangshui River, SW China during the late Holocene. The results show that tufa was deposited in this short river only between c . 4280 and c . 110 years BP. Based on the characteristics of δ 13 C values of the complete tufa profile in the river, three stages of land-cover conditions in the headwater area could be identified. The earliest, Stage I, contained the most extensive vegetation cover with mainly C3 plants, as shown by the lightest δ 13 C value, whereas the latest, Stage III, had the least land cover, reflected by the heaviest δ 13 C value. By comparison of speleothem and historical records, it was found that the land cover in Stage I was controlled mainly by climate change, whereas the land-cover changes in the later two stages were most probably related to major human disturbance (land use), especially since the Qin Dynasty and Ming Dynasty, in the headwater area of the river.

Abstract Geoarchaeological research within Sicily continues to characterize the effects of anthropogenic and geological processes upon the island's Holocene alluvial landscape developments. Interdisciplinary approaches have been used including geomorphological mapping, archaeological survey and excavations to characterize land-use practices though the mid- to late Holocene. Landscape development changes are recorded in the alluvial sediments as a consequence of land use by the indigenous and Roman settlers of Sicilian valleys in the Nebrodi and Polizzo Mountains. A marked change in erosion has been identified during the late Roman occupation of Sicily, probably as a product of intensive pastoralism and land clearing. Sedimentation during indigenous hilltop occupation of north–central and western Sicily was dominated by coarse-grained (cobble or boulder) deposits attributed to flash-flooding. Sedimentation that temporally coincided with the Greek and later Roman occupation of the adjacent valleys is marked by fine-grained deposits. These data continue to support the geological and archaeological interpretations of human–landscape interactions in Sicily. Furthermore, such geoarchaeological data may be used in models to strengthen our present and future landscape conservation methods.

Abstract The Late Quaternary geomorphology and stratigraphy of the Big Fork River valley, within the Rainy River basin of northern Minnesota, reveals evidence of prehistoric human interaction with late Holocene riverine environments. By 11 000 14 C BP, deglaciation made the region inhabitable by human groups using Clovis artefacts. Human habitation would also have been possible during the Moorhead low-water stage of glacial Lake Agassiz, starting at 10 500 14 C BP. Near its confluence with the Rainy River, the valley floor of the Big Fork valley consists of a floodplain complex and two terraces. The multi-component stratified Hannaford site is situated within the active floodplain. Overbank deposits contain artefacts in primary context, whereas artefacts within the point bar deposits are in secondary archaeological context; these deposits are associated with changing alluvial settings as the river moved eastward. Aggradation of the valley fill beneath the lowest surface (T 0 , floodplain complex) began by 3000 years ago and is associated with human activities focused on seasonal fishing and the use of riparian resources from 1300 to 650 14 C BP.

Abstract Beginning with the earliest organized habitation sites the options provided by the regional environment have largely or partially governed the location and relocation of human settlements. The settlement system in second millennium BCE Henan Province, China, evolved during a period of significant climatic change and shifting river courses but relative soil stability. Human–environment interactions across the landscape have left ample remains for investigation by scholars of social and cultural change and by natural scientists. The social effects of climate and geomorphological change during this period are complex and only partially understood. It is well documented that long-term soil stability before and during the second millennium BCE gave rise to the development of good agricultural soils, without which population expansion probably could not have taken place. This paper summarizes some of the recent research in climate change and, from two of our own projects, in geomorphology and ecology that underlie environmental impacts on the evolving state-level societies, especially related to settlement location and relocation. For example, the Shang possibly relocated one or more capital sites in response to disastrous floods.

Abstract Palaeoenvironmental investigations were carried out in the Siedlungskammer (prehistoric settlement area) Burgweinting (Regensburg, Bavaria, Germany) to reveal past settlement conditions and human impact on the environment. Two sequences were obtained from the Islinger Mühlbach Fen, in close proximity to the archaeological excavation site in Burgweinting, which documents an almost continuous settlement history since the Neolithic Period. The analyses of the sequences comprise stratigraphic, geochemical and microscopic charcoal analyses. For chronological information, radiocarbon dating was conducted on a total of 10 samples. Thus, the first long-term fire record was reconstructed for the investigation area, and the results were correlated, based on radiocarbon dating, with the available environmental information and settlement history in the Siedlungskammer Burgweinting. The fire record reveals an almost continuous, but alternating fire history. Furthermore, it shows that fire played an important role in the Siedlungskammer Burgweinting and that most probably as early as the Mesolithic hunterer–gatherers deliberately used fire.