Mineral weathering in forest soils and its relevance to the preservation of the buried archaeological resource

There is more woodland in Britain now than for many centuries and considering many international climate change mitigation policies, woodland cover, both in Britain and internationally, is being promoted. However, neither the management of existing woodlands nor their expansion should be at the expense of important archaeological evidence. Due to the large number of known archaeological sites, the large areas of land with uninvestigated archaeological potential and the expanding woodland cover, suitable mitigation strategies need to be developed to allow preservation in situ of important sites. An understanding of how woodland soils and the buried archaeological resource interact is, therefore, essential. This paper utilises ongoing environmental research into the mineral weathering rates in forest soils and considers its application to artefact preservation. The study concludes that soil water pH, its movement, and the saturation of dissolved ions in the soil solution are major factors determining both mineral and artefact longevity. A simple guide to artefact longevity based on these properties is proposed and a geochemical model for predicting loss is tested. These tools could be applied to any soil or individual horizon irrespective of land-use.     

Chemical characterisation of anthro-technosols from Bronze to Middle Age in Bologna (Italy)

The aim of this research was the understanding of a peculiarly expanded soil sequence in Bologna (i.e., Roman Bononia, Etruscan Felsina), one of the most important archaeological poles for Etruscan colonisation and settlement in northern Italy. The uppermost part of the chronological sequence dating from the Bronze Age up to medieval and modern times was analysed for the first time from geochemical and pedological viewpoints. The integration of archaeological, stratigraphical and pedological data supported by soil chemical analysis, a fundamental key for reconstructing a correct evolutionary sequence, made it possible to recognise seventeen buried Soil Units (ancient Technosols, Anthrosols and Cambisols) characterised by different kinds and degrees of intensity of anthropogenic influence. In some cases, the results show a relatively severe element concentration (Cu, Sn) mainly characterising the Iron Age (Etruscan and Villanovan) stratigraphic units, representing an ancient industrial pollution linked to local dispersal of melting activity dump products generated in near-site surrounding areas. Therefore, a comparison was possible between natural blank and anthropogenically polluted geochemical values for some local soils.     

Integrating pedological and geophysical methods to enhance the informative value of an archaeological prospection – The example of a Roman villa rustica near Regensburg,Germany

Geophysical prospection techniques are widely used to visualize the buried past. Various methods such as magnetometry, electric resistance mapping and electric resistivity tomography and ground penetrating radar yield different results. The use of all three techniques in combination with aerial photography interpretation and pedological mapping is highly effective, but it requires a multi-layer approach. This paper presents such a multi-layer approach carried out at a site with buried remnants of a Roman villa rustica in southern Germany. The integration of the various results into a geographical information system leads to a geocodation of all outcomes and a final archaeological interpretation. Several buildings in different states of preservation, different kinds of ground floors both with and without hypocausts, perimeter walls and kilns could all be detected. The soil mapping results helped in the geophysical interpretation by outsourcing soil erosion and accumulation areas. It is shown that none of the employed methods could have supplied all the compiled information on their own, and the strengths and weaknesses of each method is discussed in order to point out the implications for archaeologists.     

Optimum temporal and spectral window for monitoring crop marks over archaeological remains in the Mediterranean region

This paper aims to explore the formation of crops marks over archaeological features using remote sensing data. Crop marks are very important to archaeological research since they can reveal in an indirect way buried archaeological remains. Several researches have been able to locate subsurface relics via interpretation of multispectral and hyperspectral satellite images. However the best phenophase (time-window) where these crop marks are enhanced and which spectral bands are the most capable for this enhancement are still an open question for the scientific community. This study aims to address these fundamental aspects of Remote Sensing Archaeology. For this reason an extensive dataset was used: two control archaeological sites were constructed in two different areas of Cyprus (Alampra and Acheleia). In these areas both barley and wheat, were cultivated. In situ spectroradiometric measurements were taken over a whole phenological cycle (2001–2012) for both areas. More than 30 in situ campaigns were performed and more than 2600 ground measurements were collected. The phenological analysis of these measurements have shown that a period of only 15 days is best suitable for monitoring crop marks which is connected with one phenological stage; during the beginning of the boot stage of the crops. This period can be used in areas having similar climatic condition as Cyprus (Mediterranean region). Also as it was found, this phenological stage of crops might be also influenced by the climatic conditions of the area. The evaluation of a proposed Archaeological Index was performed at the Thessalian plain (central Greece), where several Neolithic settlements are established. The evaluation was made using both Hyperion and Landsat images. The results have shown that the proposed Archaeological Index is suitable for the enhancement of crop marks in satellite imagery.     

Evaluating Natural Site Formation Processes in Eolian Dune Sands: A Case Study from the Krmpotich Folsom Site,Killpecker Dunes,Wyoming

Eolian dune sands commonly contain archaeological material in both surface and buried contexts. However, because of the dynamic nature of dunes, the original context of an archaeological site can be severely modified or destroyed as a result of post-occupational geomorphic processes. This paper examines a Folsom occupation associated with a buried soil in the Killpecker Dunes in southwestern Wyoming. Field and labortory data are compared to determine the likely scenario of natural site formation processes responsible for the current context of the archaeological assemblage. Two primary eolian stratigraphic units are present at the site, and are separated by the buried artefact-bearing soil. Radiocarbon and optical luminescence ages indicate that the Folsom artefacts occur across a temporal hiatus, and that the buried soil is late Holocene in age. Sedimentological data indicate that the highest frequencies of artefacts by depth are associated with an erosional contact characterized by a concentration of coarse-grained material. Thus, the Folsom assemblage appears to have been vertically displaced as a result of post-occupational erosion and deflation. This case study indicates that evaluating the context of an archaeological occupation in a dune setting is best carried out utilizing multiple lines of evidence derived from both field and laboratory work.     

Neolithic occupation and mid-Holocene soil formation at Encosta de Sant'Ana (Lisbon,Portugal): a geoarchaeological approach

Excavations at the archaeological site of Encosta de Sant'Ana (Lisbon, Portugal) uncovered a mid-Holocene buried alluvial soil associated with early Neolithic occupation layers. Routine laboratory analyses and micromorphological observations were undertaken on the soil material. Humic acids from its Ab horizon, as well as Neolithic ecofacts, were radiocarbon dated. The dates obtained indicate that soil was formed between c. 8.0 and 6.0 cal ka BP and that the pedological evidence fits the record of the North Atlantic Holocene IRD events (“Bond events”) and the so-called “Holocene climate optimum”. The geoarchaeological record reveals that Neolithic inhabitants settled upon a stable surface, still affected by soil formation that was suddenly interrupted by slope wasting, probably in correspondence to Bond event 4, at c. 6.0 cal ka BP.     

Cultural Niche Construction and Remote Sensing of Ancient Anthropogenic Environmental Change in the North Coast of Peru

Archaeological land use results in the modification of natural environments according to cultural templates and strategies. Deeply entrenched environmental legacies can result from such “niche construction,” influencing subsequent cultures and continuing to resonate in modern ecological function. These changes can be better understood through archaeological remote sensing.Here, I describe spectral responses of densely vegetated sugarcane fields in the Chicama Valley (north coast of Peru) to archaeological features and associated anthropogenic soils (anthrosols). Ongoing satellite remote sensing documents approximately 440 previously unrecorded major archaeological monuments and smaller features within a 310 km² sample of the Chicama Valley The majority of these date to the Moche–Chimu periods (ca. AD 300–1400), with others dating to the Cupisnique–Colonial periods. The newly recorded features are significant for accurately reconstructing the socio-ecological history of anthropogenic environmental change in the region.In addition to advancing analyses of archaeological settlement, these results reveal how prehispanic land use legacies result in persistent anthropogenic niches that can affect modern agricultural potentials. The relationships between anthropogenic features and sugarcane development can be directly evaluated through vegetation indices and physically based image transforms. Phenological response is linked to long-term alterations in soil texture, organic-matter content, and moisture capacity. Past land use thus has a significant impact upon contemporary ecological function, resulting in anthropogenic microenvironments. As sugarcane increasingly is an important industrial crop, these results have the potential to be widely applied to archaeological and agronomic problems, including reconstructions of archaeological landscapes, understanding persistent anthropogenic environments, and mitigating heritage loss while potentially improving precision agriculture.     

Relevance of soil biology and fertility research to archaeological preservation by reburial

Abstract

This paper discusses how soil biological information can help to improve understanding of, and possibly inform decisions about, preservation of organic archaeological remains by reburial. A brief summary of the properties of the soil biological community is followed by an outline of results from recent biological investigations following the recovery of archaeologically relevant materials that had been buried for thirty-three years in one of the experimental earthworks in England UK. Examples from the soil biology and fertility literature are discussed to illustrate the effects of fluctuations in soil wetness and aeration, and of nitrogen availability on decomposition. Finally, the impact of soil handling and physical disruption on biological processes in soil are discussed, as they influence whether soil functions can be restored at a reburial site once the archaeological resources have been ‘protected’ beneath.     

The use of geosynthetics for archaeological site reburial

Abstract

Applications of geosynthetic materials in reburial practice include geotextiles for separation, filtration and protection (cushioning); geomembranes and geosynthetic clay liners for infiltration control; geonets and geocomposites for sub-surface drainage; and geocells for erosion control. Mechanically stabilized earth reinforcement using geocells, geogrids and geotextiles can also provide substantial benefits for reburial projects by reducing lateral earth pressure against backfilled structures. Other aspects of modern geotechnology that may be useful for reburial projects include micro-piles and soil nailing for foundation and excavation support and evapotranspirative capping technology to establish the depth of soil cover required to isolate a structure or artefact from moisture and temperature fluctuations. Optimal application of these geotechnologies requires an understanding of the basic engineering principles associated with their implementation, as well as knowledge of the factors influencing archaeological site preservation.     

Detection of exposed and subsurface archaeological remains using multi-sensor remote sensing

Multi-sensor airborne remote sensing has been applied to the Itanos area of eastern Crete to assess its potential for locating exposed and known buried archaeological remains, and to delineate subsurface remains beyond the current limits of ground geophysical data in order to permit future targeted geophysical surveys and archaeological excavations. A range of processing techniques (e.g., Reed–Xiaoli anomaly detection) have been applied to the CASI, ATM and lidar data in order to detect anomalies based on the premise that buried remains are likely to alter the physical and chemical characteristics of the soil compared with those of the surroundings due to variations in soil depth and drainage. Through a combination of CASI, ATM and lidar data, surface remains have been classified and mapped effectively using an object-oriented approach. The detection of subsurface remains is more problematic; however, the thermal data is most promising in this respect. The value of capturing multi- or hyperspectral data at a high spatial resolution has been demonstrated as well as the additional benefits of combining these with airborne lidar.     

Native grasslands and the stabilization of earthwork archaeological sites on the middle Missouri River,North Dakota

Abstract

Site condition and management practices at six Missouri River archaeological sites are reviewed and the condition of the sites compared between observations in 1993 and 1998. Earthwork sites in a cover of prairie or pasture grasses that have been mown for interpretation purposes have become more infested with ground squirrels. Tall prairie or shrubland obscures site features but these animals are less numerous on sites with such cover. One mown site in an urban area had no ground squirrels, suggesting that the animals had been removed by local urban dwellers or their cats and had no chance to re-invade. The long-term stability of archaeological sites can best be achieved by allowing native prairie grasses to grow tall, leaving only small samples of the site area open, or by control of ground squirrel numbers.     

Long-term agrarian landscapes in the Troodos foothills,Cyprus

We investigate the temporal and environmental relationships between the terraced hill slopes of Politiko-Koloiokremmos and the adjacent Bronze Age settlement of Politiko-Troullia in foothills of the Troodos Mountains, central Cyprus. Mapping of 102 stone walls on Koloiokremmos is compared with 66 walls farther afield on Cyprus to create a six-part terrace typology. Sherd counts from 174 2-m radius collection circles over approximately 20 ha on Troullia and Koloiokremmos were used to create interpolated sherd density surfaces revealing distinctly different patterns of land use for four major archaeological eras between the Cypriot Bronze Age and Medieval Period. We compared sherd density patterns according to terrace types, length, slope and vegetation cover determined by SAVI (Soil-Adjusted Vegetation Index) from Ikonos and Quickbird satellite imagery.The most robust sherd patterning indicates Prehistoric Bronze Age settlement at Troullia, as confirmed by soil resistivity and excavation, and multi-period land use on Koloiokremmos immediately upslope of the village that may be associated with agricultural terracing. Scattered sherd concentrations indicate later use of this landscape as an agricultural hinterland for the Iron Age city of Tamassos. Sherds and a down slope spread of roof tiles from the Roman through Medieval periods suggest an isolated structure near the crest of Koloiokremmos. Longer terraces correlate with greater vegetation cover and are interpreted as agricultural, while shorter terraces, apparently for erosion control and arboriculture, are significantly related to Prehistoric Bronze Age sherd patterns. Our results suggest that coordinated analysis of archaeological, geographical and remotely sensed environmental data associated with terraced landscapes can be used to infer long-term patterns of agricultural land use.     

The persistence of caffeine in experimentally produced black drink residues

Black drink is a native North American caffeinated tea produced from the leaves of Ilex vomitoria. The beverage was an important part of prehistoric Southeastern culture, as it was the only native source of caffeine in North America. The leaves of I. vomitoria were, therefore, a potentially valuable trade resource during the period. As such, the ability to identify archaeological black drink residues is useful to Southeastern archaeologists. In order to determine the plausibility of detecting I. vomitoria in residues, black drink was repeatedly produced in experimental unglazed pottery. The resulting potsherds were buried in several environmental contexts, recovered, and underwent absorbed pottery residue analysis. After two months of burial in three different soil types, plus a control stored in the freezer, caffeine was well-preserved in all sherds, suggesting that caffeine is a potentially useful biomarker for the detection of black drink.     

Revisiting the potential of carbonized grain to preserve biogenic 87Sr/86Sr signatures within the burial environment

Strontium (Sr) isotope analysis of archaeological crops is a potential method of provenancing and identifying the movement of crops in the past, but there remains uncertainty about whether original ⁸⁷Sr/⁸⁶Sr values can be obtained from carbonized buried grains. We have determined that hydrochloric acid (HCl) leaching removes some, but not all, exogenous Sr from carbonized cereal grains buried in soil for up to one year. We conclude that while further work could refine the leaching method, Sr isotope analysis of archaeological cereal grains can distinguish crops sourced from outside a particular (e.g., local) area if it can be shown that leaching moves grain ⁸⁷Sr/⁸⁶Sr values significantly away from the expected Sr signature.     

A Qualitative Approach for Assessment of the Burial Environment by Interpreting Soil Characteristics; A Necessity for Archaeological Monitoring

Abstract

Modern-day archaeological monitoring is often hampered by lack of money, lack of time, inadequate measuring equipment, and lack of insight in the conservation potential of a site.

Although in modern archaeological excavations soil characteristics are noted (colour, texture, groundwater level, and sometimes mineralogy), these characteristics are mainly used for the interpretation of a site. However, by looking to these characteristics from a conservational view eventually combined with the conservation status of the archaeological objects, much can be learned about the burial environment. This is essential for optimizing archaeological monitoring.

Degradation processes result from the change of reactive phases in the soil or the site. Reactive phases are soil components such as organic matter, sulfides, iron(hydr)oxides and carbonates (chalk, shells), and, if present, components in the ground or interstitial water such as hydrogen ions and sulphate. The presence of these phases can easily be established by the archaeologist or soil scientist in the field. We propose a simple field-based method for assessing degradation processes essential for in situ preservation and monitoring.     

Short-chain n-alkanes (C16–20) in ancient soil are useful molecular markers for prehistoric biomass burning

The incorporation of plant biomass into soil usually leads to long-chain n-alkanes with a relative predominance of odd carbon numbered homologues. Contrastingly, an increase in short-chain even carbon numbered n-alkanes was found in charred biomass with progressing temperatures. We applied lipid analysis to buried ancient topsoils that contained charred organic matter and to corresponding control soils, which were characterized by a lighter color and lower contents of charred materials. Commonly, the proportion of lipid extracts was found to be lower in the ancient soil than in the control samples, which indicated an enhanced degradation of organic matter, e.g., by thermal degradation. All samples displayed a particular pattern of short-chain and even carbon numbered n-alkanes (maximum at n-C₁₆ or n-C₁₈). The ratios CPI (carbon preference index) and ACL (average chain length) for the investigated soil samples matched the ratios found for maize and rye straw charred at 400 °C or 500 °C, respectively. These molecular ratios indicate the presence of charred biomass. The predominance of short-chain and even carbon numbered n-alkanes was a result of thermal degradation of biomass. The degradation products were preserved in ancient soils and could be applied as molecular markers in archaeological or palaeoenvironmental research.     

An Analytical Methodology for the Study of the Corrosion of Ferrous Archaeological Remains in Soils

Abstract

In the context of the cultural heritage, a methodology based on ?eld and laboratory approaches is developed for studying the long-term corrosion of iron. Moreover it has been adapted to the study of archaeological artefacts buried in anoxic soils in the speci?c case of in situ preservation. The environmental parameters are determined on the archaeological sites and artefacts are collected and characterized using complementary multi-scale techniques. Moreover, laboratory experiments are performed to locate the reaction sites inside the corrosion layer and to identify its electronic properties. The results allow estimation of a low corrosion rate for iron buried in an anoxic soil (under 2 μm/year) and the proposal of a mechanism based on a decoupling of the anodic and the cathodic sites. Then a diagnosis of the alteration state of the samples is established.     

Seasonality and paleodiet in the Chiribaya polity of southern Peru

In the Andes, the complex Chiribaya polity, or señorío, was composed of economically specialized groups. Previous carbon and nitrogen isotope analyses of archaeological human bone from Chiribaya-affiliated sites have effectively demonstrated socioeconomic specialization and variability in paleodiet among different Chiribaya-affiliated sites. The present study complements earlier paleodietary analyses of Chiribaya populations by supplementing them with carbon and nitrogen isotope analyses of archaeological human hair from the two Chiribaya-affiliated sites of Chiribaya Alta and El Yaral. These new data demonstrate that seasonal variability in the consumption of marine products and C₄ plants such as maize was quite high for some individuals buried at Chiribaya-affiliated sites. In addition to elucidating the complex patterns of Chiribaya seasonality, this study contributes to the growing body of knowledge of archaeological analyses of human hair for paleodiet.     

Stratigraphy and geochronology of La Playa archaeological site,Sonora, Mexico

La Playa archaeological site in northern Sonora, Mexico contains a long record of human activity that includes the Paleoindian period (terminal Pleistocene) and much of the Holocene. The size and complexity of La Playa has discouraged a systematic characterization of its stratigraphy and geochronology, a deficiency we redress in the study. We distinguished seven stratigraphic units ranging in age from >44,570 to 400 cal yr B.P. using ¹⁴C dates from charcoal and terrestrial gastropods found mostly in archaeological features. All of the buried (in situ) cultural remains are contained in Units B (4690–1580 cal yr B.P.) and C (1010–400 cal yr B.P.) and represent overbank deposition from the nearby Rio Boquillas. Occupation at the site peaks in Units B₄ and B₅, corresponding to the Cienega phase (2800–1800 cal yr B.P.) of the Early Agricultural period. This period coincides with the growth of early agricultural villages in the region and is marked at La Playa by thousands of archaeological features including roasting pits, human burials, and extensive canal irrigation systems. The presence of semi-aquatic and aquatic snails demonstrates that water was present year round in the canal systems constructed during this period. Stable and radiometric isotopic evidence suggests that early agriculturalists diverted ground water over several kilometers from the nearby Rio Boquillas. The extensive Cienega phase occupation ended after about 1700 cal yr B.P. with deep erosion of the site, an event also visible in alluvial records in southern Arizona that marked the end of the Early Agricultural period and significant changes in settlement organization in the region.     

Chemical and Pedological Delimiting of Deeply Stratified Archaeological Sites in Frozen Ground

Abstract

Delimiting and testing deeply stratified archaeological sites in frozen ground is facilitated by drilling and analyzing soil cores. After a test grid of the proposed area has been surveyed, a lightweight, portable diamond drill is used to sample those subareas selected through the use of (1) surface clues, (2) test-pit data, and (3) knowledge of standard site patterns of the cultures represented. Gross core analysis demonstrates soil profile continuities and discontinuities throughout the site. Munsell colours, thicknesses and gross inclusions of soil levels are recorded before thawing of the cores. Most cultural and human chemical residues are studied following thawing and dissection of the cores. The locations of bone, lithics, and human waste in frozen arctic and alpine soils and possibly in augured southern soils aid in vertical and horizontal site delimitation. Small samples of archaeologically important trace chemicals such as bone apatite and phosphorous can be taken for field analysis. Reflected fluorescence caused by ultraviolet light on apatite in buried bone may be measured spectrophotometrically by lowering an appropriate probe in the drill hole and plotting light intensity with depth of levels. Primary application of soil-core studies is pedological.