Animal Burrowing Research Articles

Risk-based maintenance and inspection of riverine flood defence systems

The condition of flood defence revetments is influenced by many different degradation processes such as animal burrowing, rutting and growth of weeds. Many of these processes are shock-based rather than progressive continuous. As shocks can cause a drop in performance, this means that the condition of a revetment can suddenly decrease, meaning that revetments can have significant initial damage at the beginning of a storm. Combined with the limited detection probability of common visual inspections of flood defences, this can have a significant influence on the reliability of flood defence systems, something typically not considered in reliability analysis. In this paper we study the reliability of a flood defence system subject to shock-based degradation. Various maintenance concepts are compared for a case study of a riverine flood defence of 20 kilometres length. This demonstrates that the current maintenance concept is insufficient to satisfy the reliability requirements for failure of the revetment. Overall, the joint influence of degradation and the existing maintenance concept leads to a 20 times higher failure probability estimate compared to a typical assessment without these aspects. Next, we demonstrate that both additional inspections, and targeted interventions to reduce the impact of for instance animal burrowing, can significantly reduce total cost and improve robustness of the considered flood defence system.

Mammalian bioturbation amplifies rates of both hillslope sediment erosion and accumulation along the Chilean climate gradient

Abstract. Animal burrowing activity affects soil texture, bulk density, soil water content, and redistribution of nutrients. All of these parameters in turn influence sediment redistribution, which shapes the earth's surface. Hence it is important to include bioturbation into hillslope sediment transport models. However, the inclusion of burrowing animals into hillslope-wide models has thus far been limited and has largely omitted vertebrate bioturbators, which can be major agents of bioturbation, especially in drier areas. Here, we included vertebrate bioturbator burrows into a semi-empirical Morgan–Morgan–Finney soil erosion model to allow a general approach to the assessment of the impacts of bioturbation on sediment redistribution within four sites along the Chilean climate gradient. For this, we predicted the distribution of burrows by applying machine learning techniques in combination with remotely sensed data in the hillslope catchment. Then, we adjusted the spatial model parameters at predicted burrow locations based on field and laboratory measurements. We validated the model using field sediment fences. We estimated the impact of bioturbator burrows on surface processes. Lastly, we analyzed how the impact of bioturbation on sediment redistribution depends on the burrow structure, climate, topography, and adjacent vegetation. Including bioturbation greatly increased model performance and demonstrates the overall importance of vertebrate bioturbators in enhancing both sediment erosion and accumulation along hillslopes, though this impact is clearly staggered according to climatic conditions. Burrowing vertebrates increased sediment accumulation by 137.8 % ± 16.4 % in the arid zone (3.53 kg ha−1 yr−1 vs. 48.79 kg ha−1 yr−1), sediment erosion by 6.5 % ± 0.7 % in the semi-arid zone (129.16 kg ha−1 yr−1 vs. 122.05 kg ha−1 yr−1), and sediment erosion by 15.6 % ± 0.3 % in the Mediterranean zone (4602.69 kg ha−1 yr−1 vs. 3980.96 kg ha−1 yr−1). Bioturbating animals seem to play only a negligible role in the humid zone. Within all climate zones, bioturbation did not uniformly increase erosion or accumulation within the whole hillslope catchment. This depended on adjusting environmental parameters. Bioturbation increased erosion with increasing slope, sink connectivity, and topography ruggedness and decreasing vegetation cover and soil wetness. Bioturbation increased sediment accumulation with increasing surface roughness, soil wetness, and vegetation cover.

Higher sediment redistribution rates related to burrowing animals than previously assumed as revealed by time-of-flight-based monitoring

Abstract. Burrowing animals influence surface microtopography and hillslope sediment redistribution, but changes often remain undetected due to a lack of automated high-resolution field monitoring techniques. In this study, we present a new approach to quantify microtopographic variations and surface changes caused by burrowing animals and rainfall-driven erosional processes applied to remote field plots in arid and Mediterranean climate regions in Chile. We compared the mass balance of redistributed sediment between burrow and burrow-embedded area, quantified the cumulative sediment redistribution caused by animals and rainfall, and upscaled the results to a hillslope scale. The newly developed instrument, a time-of-flight camera, showed a very good detection accuracy. The animal-caused cumulative sediment excavation was 14.6 cm3 cm−2 yr−1 in the Mediterranean climate zone and 16.4 cm3 cm−2 yr−1 in the arid climate zone. The rainfall-related cumulative sediment erosion within burrows was higher (10.4 cm3 cm−2 yr−1) in the Mediterranean climate zone than the arid climate zone (1.4 cm3 cm−2 yr−1). Daily sediment redistribution during rainfall within burrow areas was up to 350 %(40 %) higher in the Mediterranean (arid) zone compared to burrow-embedded areas and much higher than previously reported in studies that were not based on continuous microtopographic monitoring. A total of 38 % of the sediment eroding from burrows accumulated within the burrow entrance, while 62 % was incorporated into hillslope sediment flux, which exceeds previous estimations 2-fold. On average, animals burrowed between 1.2–2.3 times a month, and the burrowing intensity increased after rainfall. This revealed a newly detected feedback mechanism between rainfall, erosion, and animal burrowing activity, likely leading to an underestimation of animal-triggered hillslope sediment flux in wetter climates. Our findings hence show that the rate of sediment redistribution due to animal burrowing is dependent on climate and that animal burrowing plays a larger than previously expected role in hillslope sediment redistribution. Subsequently, animal burrowing activity should be incorporated into soil erosion and landscape evolution models that rely on soil processes but do not yet include animal-induced surface processes on microtopographical scales in their algorithms.

Interaction Between Animal Burrowing and Loess Cave Formation in the Chinese Loess Plateau

Although the interactions between biotic and geomorphic processes usually occur on small spatial and short temporal scales, many of the mechanisms remain to be investigated. This study provides the first direct evidence of the interaction between biotic burrowing and loess cave formation in the Chinese Loess Plateau (CLP). The study area is the Qingshui Valley in the western CLP, near Lanzhou. We surveyed the target site (with an area of ∼13,367 m2) four times from Jul 2019 to Dec 2020, using an unmanned aerial vehicle (UAV). High resolution UAV images enabled us to determine the temporal and spatial dynamics of biotic burrowing and loess caves. The results show that loess caves tended to develop down valley below collapses, while animal burrows were preferentially located upslope away from collapses. Despite the distinct “topographic niches” for both biotic and abiotic processes, we observed an interaction between the two processes in space when tracking their temporal dynamics. Three out of seven new loess caves were in the process of formation at typical “topographic niches” of animal burrows and there was a significantly high animal burrow density around these three caves before their initiation. These results indicate that the three caves were directly initiated from animal burrows and/or developed under the influence of biotic activities. Therefore, biotic burrowing promotes the spatial heterogeneity of loess cave distribution. We also found significant decreases in animal burrow density surrounding the newly-formed loess caves after their initiation. This may reflect a risk avoidance strategy of animal burrowing, which causes animals to avoid areas of recent mass movement (i.e., collapses and new caves). The formation and expansion of loess caves can dictate the distribution of active areas of biotic disturbance. Our results demonstrate a clear interaction between biotic burrowing and loess cave formation, and they emphasize the role of biological agents as a mechanism for the formation of loess caves, which enrich the understanding of searching fingerprints of life during landscape evolution.

Accuracy of visual inspection of flood defences

Prioritisation of flood defence maintenance is typically based on visual inspection. However, literature shows that the Probability of Detection (PoD) of visual inspection can vary significantly. Here we investigate the PoD for visual inspections of flood defence structures, the consistency of damage classification, and the influence of different variables on the PoD, such as past experience. Four flood defence sections were inspected by 22 different inspectors for a variety of damage types, such as animal burrowing and damage to block revetments. It is found that the PoD varies significantly both per damage type and inspector. Additionally, the estimated severity of damages varies significantly in comparison to the reference situation: over half of the registered damages is assigned a different severity compared to the reference, which potentially leads to incorrect maintenance measures. A likely explanation for the variation in results is the complexity of inspection guidelines and task definitions. Therefore it is advised to simplify inspection guidelines and use more focussed inspections for the most important types of damage. This likely leads to both a reduction of the number of false negatives associated with an increase in flood risk, and better risk-based asset management and maintenance prioritisation in general.

Eocene animal trace fossils in 1.7-billion-year-old metaquartzites

The Paleoproterozoic (1.7 Ga [billion years ago]) metasedimentary rocks of the Mount Barren Group in southwestern Australia contain burrows indistinguishable from ichnogenera Thalassinoides, Ophiomorpha, Teichichnus, and Taenidium, known from firmgrounds and softgrounds. The metamorphic fabric in the host rock is largely retained, and because the most resilient rocks in the sequence, the metaquartzites, are too hard for animal burrowing, the trace fossils have been interpreted as predating the last metamorphic event in the region. Since this event is dated at 1.2 Ga, this would bestow advanced animals an anomalously early age. We have studied the field relationships, petrographic fabric, and geochronology of the rocks and demonstrate that the burrowing took place during an Eocene transgression over a weathered regolith. At this time, the metaquartzites of the inundated surface had been weathered to friable sandstones or loose sands (arenized), allowing for animal burrowing. Subsequent to this event, there was a resilicification of the quartzites, filling the pore space with syntaxial quartz cement forming silcretes. Where the sand grains had not been dislocated during weathering, the metamorphic fabric was seemingly restored, and the rocks again assumed the appearance of hard metaquartzites impenetrable to animal burrowing.

Radon fluxes at four uranium mill tailings disposal sites after about 20 years of service

To evaluate the properties of earthen covers over uranium mill tailings disposal cells after about 20 years of service, we measured Rn-222 fluxes and radon barrier properties at the Falls City, TX, Bluewater, NM, Shirley Basin South, WY, and Lakeview, OR disposal sites in western USA. A total of 115 in-service Rn fluxes were obtained at 26 test pit locations from the top surface of the exposed Rn barrier (i.e., after protective layers were removed by excavation) and 24 measurements were obtained from the surface of the underlying waste after excavation through the Rn barrier layer. Rn-222 concentrations were determined in accumulation chambers using a continuously monitoring electronic radon monitor (ERM) equipped with a solid-state alpha particle detector. Effects of surface features on Rn flux including vegetation, seasonal ponding, and animal burrowing were quantified. Comparison of measured fluxes with values that were measured shortly after the Rn barriers were completed (as-built) show that most measurements fell within the range of the as-built fluxes, generally at very low fluxes. At two sites fluxes were measured that were greater than the highest as-built flux. High fluxes are typically caused by a combination of enhanced moisture removal and preferential pathways for Rn transport, often caused by deep-rooted plants. Such localized features result in a spatially heterogeneous distribution of fluxes that can vary substantially over only a meter or two.

Subsurface condition assessment of critical dam infrastructure with non-invasive geophysical sensing

Recent cases of dam failures indicate that the safe operation and proactive maintenance of critical infrastructure is of significant importance considering the growing number of ageing dams and the increase in intensity and frequency of extreme climatic events. The current procedures to assess the performance of dam infrastructure, usually based on geodetic and geotechnical instrumentation, do not provide repeatable and reliable information with regard to subsurface hazards that evolve within the body of earth-fill dams that could compromise the integrity of the structure. This increases the risk of failure with significant socio-economic impacts and long-term disruption on downstream communities. On the contrary, geophysical methods can provide advanced information about subsurface hazards and can therefore significantly assist to define the safety level of dam infrastructure. This will enable early remedial maintenance and repair actions to be carried out enhancing public safety and eventually reducing costs for asset owners. This study presents for the first time the investigation of the condition of three reservoir dams in Scotland with the application of two complementary non-invasive geophysical methods coupled with visual inspection. Electromagnetic (EM) sensing was initially employed to provide an assessment of the upper soil layers of the crest and downstream shoulder of the dam. Electrical Resistivity Tomography (ERT) arrays were then installed on the crest to assess the subsurface conditions of the dam based on the resistivity signatures. The analysis of the geophysical models identified weak zones within the body of dams associated with high-resistivity patterns associated with potential animal burrowing activity and fissuring on the crest of the dam. The electrical resistivity surveys revealed low-resistivity zones influenced by seepage conditions inside the body of dams but also provided an indication of potential internal erosion areas. Finally, the geophysical models provided an insight of the homogeneity of the fill material and determined the dam foundation characteristics. The geophysical results presented in this investigation provide important baseline measurements and key information about the current condition and on-going performance of dam infrastructure.

Soil Structure and Its Relationship to Shallow Soil Subsidence in Coastal Wetlands

Accelerating sea-level rise poses a threat to mangroves and salt marshes. Sediment accretion on the soil surface and belowground root production is proposed to increase soil elevation enabling these intertidal habitats to maintain their position relative to mean sea level. However, shallow soil subsidence is frequently observed, which may cancel out or even outweigh the positive effects of surface accretion and root production on soil elevation gains. The processes that lead to shallow soil subsidence have not often been investigated. Here, we used computed tomography (CT) imaging to determine the volume of coarse pores in the top 20 cm of 30-cm-deep soil cores collected from mangroves and salt marshes within Moreton Bay, eastern Australia. The four field sites have long-term observations of variation in soil surface elevation gain, surface accretion rate, and shallow subsidence rate using the rod surface elevation table-marker horizon (RSET-MH) method. Over our sites, we found that the rates of shallow soil subsidence were positively related to the volume of soil coarse pores and soil clay and silt content rather than to the volume of fine pores or total porosity or other soil properties. In turn, the volume of soil coarse pores was positively related to the volume of animal burrows and root mass. Fine-pore volume and total porosity of soils were negatively associated with soil bulk density, which was in turn negatively related to soil organic matter content. Our results indicate influences of differently sized soil pores in shallow soil subsidence and suggest that animal burrowing may play a role in shallow soil subsidence.

Investigation of the influence of animal burrowing on the failure of the levee of San Matteo along the Secchia river

Animal burrowing can greatly influence the water pressures in a flood protection embankment and thereby be a cause of breaching of flood defences. However, little guidance and literature is available on this subject. This paper investigates the contribution of badgers, porcupines and foxes to the failure of the levee of San Matteo (Modena, Italy) on 19th January 2014. The proposed method evaluates their influence on the water pressures in the embankment during rainfall and a high water tide. The influence of the burrowing is assessed through a transient FEM flow analysis. Starting from the documented entrances situated in the vadose zone, different scenarios for the internal distribution of tunnels and chambers are proposed. The most likely representative network for the loss of stability of the dike is assessed.

Study of the effect of burrows of European Badgers (Meles meles) on the initiation of breaching in dikes

Levees offer an ideal environment for the diffusion of European Badgers (Meles Meles), whose burrowing activity can be a main cause of breaching in dikes. This paper evaluates the contribution of burrows dug by badgers to the initiation of a dike failure. For example, a breach in a dike near Modena (Italy), where animal burrowing activity was active, took place on the 19th January 2014. While the distribution of the underground system inside the dike is usually unknown, the burrow entrances are easily identified along the slopes. Different scenarios of burrow entrances located along the outer and inner slope are considered and their contribution to sliding of the inner slope, micro-instability and internal erosion is investigated. The most dangerous positions of entrances for the stability of the dike are assessed and presented.

Stabilization of the coupled oxygen and phosphorus cycles by the evolution of bioturbation

Animal burrowing and sediment-mixing (bioturbation) began during the run up to the Ediacaran/Cambrian boundary1, 2, 3, initiating a transition4, 5 between the stratified Precambrian6 and more well-mixed Phanerozoic7 sedimentary records, against the backdrop of a variable8, 9 global oxygen reservoir probably smaller in size than present10, 11. Phosphorus is the long-term12 limiting nutrient for oxygen production via burial of organic carbon13, and its retention (relative to carbon) within organic matter in marine sediments is enhanced by bioturbation14, 15, 16, 17, 18. Here we explore the biogeochemical implications of a bioturbation-induced organic phosphorus sink in a simple model. We show that increased bioturbation robustly triggers a net decrease in the size of the global oxygen reservoir—the magnitude of which is contingent upon the prescribed difference in carbon to phosphorus ratios between bioturbated and laminated sediments. Bioturbation also reduces steady-state marine phosphate levels, but this effect is offset by the decline in iron-adsorbed phosphate burial that results from a decrease in oxygen concentrations. The introduction of oxygen-sensitive bioturbation to dynamical model runs is sufficient to trigger a negative feedback loop: the intensity of bioturbation is limited by the oxygen decrease it initially causes. The onset of this feedback is consistent with redox variations observed during the early Cambrian rise of bioturbation, leading us to suggest that bioturbation helped to regulate early oxygen and phosphorus cycles.

Pedological and geological relationships with soil lichen and moss distribution in the eastern Mojave Desert, CA, USA

Biological soil crusts (biocrusts) are ubiquitous in drylands globally. Lichens and mosses are essential biocrust components and provide a variety of ecosystem services, making their conservation and management of interest. Accordingly, understanding what factors are correlated with their distribution is important to land managers. We hypothesized that cover would be related to geologic and pedologic factors. We sampled 32 sites throughout the eastern Mojave Desert, stratifying by parent material and the age of the geomorphic surfaces. The cover of lichens and mosses on ‘available ground’ (L + Mav; available ground excludes ground covered by rocks or plant stems) was higher on limestone and quartzite-derived soils than granite-derived soils. Cover was also higher on moderately younger-aged geomorphic surfaces (Qya2, Qya3, Qya4) and cutbanks than on very young (Qya1), older-aged surfaces (Qia1, Qia2), or soils associated with coppice mounds or animal burrowing under Larrea tridentata. When all sites and parent materials were combined, soil texture was the most important factor predicting the occurrence of L + Mav, with cover positively associated with higher silt, very fine sand, and fine sand fractions and negatively associated with the very coarse sand fraction. When parent materials were examined separately, nutrients such as available potassium, iron, and calcium became the most important predictors of L + Mav cover.

Geomorphological and sedimentological precautions in radiocarbon dating of eolian and lacustrine sequences in arid Asia

Lacustrine sediments in deep lakes are suitable for establishing radiocarbon chronology. Lacustrine sediments in shallow lakes are not suitable for establishing radiocarbon chronology, simply because younger plant roots can readily penetrate into older lacustrine sediments. Three features are warning signs for shallow-lake sediments: (1) high concentration of salts, (2) abundant vertically-oriented plant residues, and (3) organic matter-enriched sand layer. Field and laboratory investigations of eolian and water-reworked eolian sequences suggest that fluvial addition and fluvial alteration on terraces may produce reversed chronologies. Fluvial layers interbedded within eolian sequences should be avoided in obtaining dating targets, and eolian layers isolated by fluvial or lacustrine layers should be the targeting layers from which dating samples should be obtained. Bulk sediment 14C dates of a paleosol at Yuanbao loess section in the western Chinese Loess Plateau are distinctively older than charcoal dates, suggesting that bulk sediment samples contain older organic carbon that was likely brought upward by animal burrowing. In contrast, bulk sediment dates were found to be systematically younger than snail and charcoal dates at the Romantic section in Eastern Kazakhstan. The younger dates likely resulted from the downward intrusion of plant roots and/or translocation of mobile organic compounds into deeper layers. The only suggestion is to avoid bulk sediments as dating targets in eolian–paleosol sequences. The misleading chronology for the upper loess–paleosol complex at Lujiagou section indicated that even continuous loess deposits may yield reversed chronologies where loess has inherited older organic carbon from deflated floodplains and from loess hills. All kinds of dating targets (including charcoals) may produce unreliable chronologies.

Processes of organic carbon in mangrove ecosystems

In addition to carbon accumulation in plants, processes of organic carbon in mangrove ecosystems include origins of sediment organic carbon, carbon fluxes between mangroves and their adjacent systems (coastal waters and atmosphere), and cycling processes. Sediment organic carbon originates from suspending solids in coastal waters, mangrove plants and benthic algae. In mangroves with low organic carbon content in sediments, tidal seawater is the main origin of sediment organic carbon, while in mangroves with high sediment organic carbon contents, sediment organic carbon mainly originates from mangrove plants. Due to tidal flush, there is large material exchange between mangrove ecosystems and their adjacent coastal waters. In China, exports of organic carbon in litter falls and dissolved organic carbon from mangroves to their adjacent coastal waters have not been documented. Processes of mangrove litter falls, including production, decomposition, export and animal consumption, determine linkages among organic carbon among mangrove plants, secondary production and coastal ocean. Consumers especially benthic animals may influence organic carbon in mangrove ecosystems, because (1) their consumption rates are high, and their selective feeding on some food sources will change the relative quantities of export, bury and mineralization of organic carbon from different origins; (2) their consumption is much more than assimilation, resulting in the changes in sizes, forms and qualities of non-assimilated organic matters, and then the changes in availability of export, consumption or mineralization of organic carbon. Respiration and sulfate reduction are important mineralization processes of organic carbon in mangrove sediments. Mineralization rates of organic carbon in mangrove sediments are influenced by quantities, activities and particle sizes of organic matters, and other factors such as forest ages, root activities and animal burrowing activities. Researches on processes of mangrove organic carbon should be based on open systems, and ecological processes of organic carbon should be coupled with vegetation restoration.

Enhanced photosynthesis and flower production in a sagebrush morphotype associated with animal burrows

Two morphotypes of the evergreen shrub Artemisia tridentata Nutt. ssp. wyomingensis occur in the Shirley Basin of central Wyoming (USA), one of which was associated exclusively with Mima-like mounds generated by animal burrowing activity. Measured on a particularly dry year according to a 34-year precipitation record, plants growing on mounds (M) versus inter-mound locations (IM)were taller with greater leaf biomass and leaf area per unit ground area, and had over 90% of all inflorescences. As a result, the landscape consists of a patchy distribution of reproductive islands (~ 20-40 m-2 in size) separated by a mean distance of ~ 30 m. In addition, greater photosynthesis per unit leaf area occurred for M plants when ephemeral leaves dominated total leaf area in spring and early summer, as well as during short time periods (< 3 days) following sporadic rainfall events in summer when only perennial leaves were present. As a result, estimated total annual carbon gain was 41% greater for M plants from May to mid-June, but was not significantly different from IM plants for the remainder of the season, resulting in a total summer carbon gain that was 14% greater in M plants. Stomatal and nonstomatal conductances to CO2 uptake were also greater for the ephemeral leaves of M plants, along with lower internal CO2 concentrations (193 ± 4 μl l-1 vs. 209 ± 8 μl-1, respectively). M plants also maintained higher xylem water potentials throughout most of the growth season (−1.1 ± 0.1 SD MPa in May, declining to −4.4 ± 0.3 SD MPa in August), along with higher water use efficiencies (photosynthesis/transpiration). M and IM soils did not differ significantly in total organic or nitrate contents, although leaf nitrogen content was higher in M plants when photosynthesis was also greater. Photosynthesis in M plants also responded more positively to afternoon showers greater than about 7 mm compared to IM plants. Thus, improved water and nutrient relations was associated with enhanced photosynthetic carbon gain in M plants, enabling greater flower production. Moreover, morphotypic plasticity coupled with the effects of animal burrows may have substantially increased sexual reproductive success in A. t. wyomingensis.

Bubble growth and rise in soft sediments

The mechanics of uncemented soft sediments during bubble growth are not widely understood and no rheological model has found wide acceptance. We offer definitive evidence on the mode of bubble formation in the form of X-ray computed tomographic images and comparison with theory. Natural and injected bubbles in muddy cohesive sediments are shown to be highly eccentric oblate spheroids (disks) that grow either by fracturing the sediment or by reopening preexisting fractures. In contrast, bubbles in soft sandy sediment tend to be spherical, suggesting that sand acts fluidly or plastically in response to growth stresses. We also present bubble-rise results from gelatin, a mechanically similar but transparent medium, that suggest that initial rise is also accomplished by fracture. Given that muddy sediments are elastic and yield by fracture, it becomes much easier to explain physically related phenomena such as seafloor pockmark formation, animal burrowing, and gas buildup during methane hydrate melting.

Animal burrowing and associated formation of large desiccation cracks as factors of a rapid restoration of soil cover in flooded farmlands

The burrowing activity of annelids controls the spatial pattern and rapid formation of large desiccation cracks in the river flood-derived mud cover in recently inundated farmland areas in northwestern Anatolia, Turkey. The phenomenon is confirmed by laboratory experiments imitating the natural floodplain conditions.

Distinguishing bioturbation and trampling using pottery sherd measures, Tell Fendi, Jordan

In the Levant, the blind mole-rat (Spalax ehrenbergi) is responsible for much disturbance at archaeological sites, but its potential destructiveness is often ignored when cultural remains are interpreted. The effects of mole-rat burrowing on artifact distributions were evaluated through a study of mole-hill contents and by doing a vertical particle-size analysis of ceramic materials drawn from Tell Fendi, a Late Chalcolithic (6600–5500 B.P.) site in the Jordan Valley. While the general effects of animal burrowing are predictable to some degree, stratigraphic units affected by burrowing may not be immediately obvious to the archaeologist. The problem of identification is compounded because other disturbance processes produce similar effects. This study proposes a method for identifying bioturbation layers and for distinguishing these layers from both trampled surfaces and in situ contexts by means of pottery sherd measures. © 2000 John Wiley & Sons, Inc.

Distinguishing bioturbation and trampling using pottery sherd measures, Tell Fendi, Jordan

In the Levant, the blind mole-rat (Spalax ehrenbergi) is responsible for much disturbance at archaeological sites, but its potential destructiveness is often ignored when cultural remains are interpreted. The effects of mole-rat burrowing on artifact distributions were evaluated through a study of mole-hill contents and by doing a vertical particle-size analysis of ceramic materials drawn from Tell Fendi, a Late Chalcolithic (6600–5500 B.P.) site in the Jordan Valley. While the general effects of animal burrowing are predictable to some degree, stratigraphic units affected by burrowing may not be immediately obvious to the archaeologist. The problem of identification is compounded because other disturbance processes produce similar effects. This study proposes a method for identifying bioturbation layers and for distinguishing these layers from both trampled surfaces and in situ contexts by means of pottery sherd measures. © 2000 John Wiley & Sons, Inc.