Black shale is a dark-colored mudrock containing organic matter that may have generated hydrocarbons in the subsurface or that may yield hydrocarbons by pyrolysis. Many black shale units are enriched in metals severalfold above expected amounts in ordinary shale. Some black shale units have served as host rocks for syngenetic metal deposits.

Black shales have formed throughout the Earth's history and in all parts of the world. This suggests that geologic processes and not geologic settings are the controlling factors in the accumulation of black shale. Geologic processes are those of deposition by which the raw materials of black shale are accumulated and those of diagenesis in response to increasing depth of burial.

Depositional processes involve a range of relationships among such factors as organic productivity, clastic sedimentation rate, and the intensity of oxidation by which organic matter is destroyed. If enough organic material is present to exhaust the oxygen in the environment, black shale results.

Diagenetic processes involve chemical reactions controlled by the nature of the components and by the pressure and temperature regimens that continuing burial imposes. For a thickness of a few meters beneath the surface, sulfate is reduced and sulfide minerals may be deposited. Fermentation reactions in the next several hundred meters result in biogenic methane, followed successively at greater depths by decarboxylation reactions and thermal maturation that form additional hydrocarbons. Suites of newly formed minerals are characteristic for each of the zones of diagenesis.

Varieties of kaolin, a rock, may be classified geologically, mineralogically, crystallographically, genetically, texturally, morphologically, by industrial use, and in other ways which are desired. In this paper, the first-order of classification used is geological, i.e., transported and residual, after which other categories are used as subdivisions.

Scan electron micrographs, SEM, of the textures of kaolin show that distinctive textures characterize the several categories of classification. Varieties in texture of kaolin include similarities to those typical of sedimentary, igneous and metamorphic rocks. Because word descriptions of the textures are inadequate in comparison to pictures of them, the reader is referred to the micrographs.

SEM's illustrate differences between kaolins which were transported, formed, or deposited from solution, a colloidal phase, or as orthodox clastic particles. The parent source of kaolin deposited, or “grown,” from solution may be difficult to ascertain. It is suggested that the total role of solution work in kaolin petrology can be more important than has ordinarily been credited.

For snow-avalanche hazard mapping, one needs efficient tools that nevertheless capture the essential physical processes. The code MoT-PSA (Method of Transport – Powder Snow Avalanche) described here is based on the two-layer depth-averaged formulation for mixed snow avalanches developed by Eglit and co-workers in the 1980s but is extended to 3-D terrain and uses a fast numerical scheme based on the method of transport. Compared to previous works, we introduce novel formulations for the suspension and deposition of snow from the dense core. Snow cover and air entrainment are quantified with physics-based models. A sensitivity study of the model parameters on an idealized topography shows that both the dense core and the parameters of the powder snow cloud (PSC) governing particle suspension and settling significantly affect the dynamics. As expected, we observe that snow cover entrainment favours the formation of large PSCs with long runout. The powder-snow avalanche that occurred in Lom (Norway) on 27 February 2020 is back-calculated using MoT-PSA. With plausible parameter values, the model reproduces the dense core stopping at the gully's base and the dilute PSC travelling across the frozen lake for almost 1 km.

The mineralogy and geochemistry of shales reflect the composition of the initially deposited precursor mud, subsequently modified by diagenetic processes. To see if significant geochemical differences exist between shales that mainly owe their present-day composition to either deposition or diagenesis, we compare the published mineralogical, bulk and clay-fraction geochemical, and clay-fraction O-isotopic compositions of 2 shales. One shale is from the Western Canada Sedimentary Basin (WCSB), and its composition mainly reflects primary (depositional) chemical and mineralogical variations (smectitic to illitic illite/smectite) within this unit. The other shale is from the United States Gulf Coast (USGC), and its composition mainly reflects mixed-layer illite/smectite (I/S) diagenesis of deposited smectitic clay material. The chemical and mineralogical trends of WCSB and USGC shales, including one of increasing illite content in I/S with depth or maturity, are essentially indistinguishable, in both bulk shale and clay fraction, despite the contrasting genetic interpretations for the origin of the contained I/S. Thus, similar mineralogical and chemical trends with depth or temperature can result either from inherited depositional compositional heterogeneity of the sediment, from burial metamorphism of shale or a combination of both. Interestingly, the O-isotopic compositions of the clay fractions from the WCSB and USGC are significantly different, a fact that reflects original clay formation from source material and water of quite different isotopic compositions. The discrimination between depositional and diagenetic contributions to shale composition continues to pose challenges, but a combination of bentonite, illite polytype, clay isotopic and trace and rare earth elemental analyses together with illite age analysis holds promise for future work.

The herbicide dicamba has injured millions of hectares of sensitive plant species in the United States since 2017. This injury has coincided with the commercialization of dicamba-resistant soybean [Glycine max (L.) Merr.] and cotton (Gossypium hirsutum L.). We quantified atmospheric deposition and mass flux of dicamba in 12 soybean production regions of Missouri. Dicamba was routinely detected in weekly deposition samples collected during agriculturally intensive spray periods. Observed concentrations were indicative of both local (<1 km) and long-distance transport (>1 km) of airborne dicamba. High-deposition events (>100 µg m−2) occurred annually in southeast Missouri, and peak dicamba deposited at these sites (12.5 to 84.0 µg m−2) was sufficient to injure non–dicamba resistant soybean. Adoption rate of dicamba-resistant crops and atmospheric stability explained much of the variance, and it is difficult for a herbicide product label to address these variables. Overall, these results demonstrated that dicamba was commonly deposited from the atmosphere during the growing season, and observed concentrations and fluxes were strongly related to the timing and magnitude of rainfall events and the amount of dicamba usage near collection sites.

Layered double hydroxides (LDHs) are often used as precursors for mixed-oxide catalysts and the deposition of a LDH layer on supporting materials would be advantageous because of better utilization of active components. The purpose of the present study was to investigate the formation of LDHs on Al2O3/Al supports prepared by the anodic oxidation of aluminum foil in dilute aqueous solutions of Co, Mn, and/or Ni nitrates. The LDH deposition was carried out under hydrothermal conditions at 80–180°C for periods ranging from 8 h to 7 days. In the initial stages of the reaction, a surface alumina hydration was observed. The LDH phase was detected after long-term deposition (3–7 days) at 120–160°C and only a small amount of Mn was incorporated in the LDHs deposited. In solutions containing only Co and Mn cations, scanning electron microscopy (SEM) images show a gradual growth of platy crystals resulting in the formation of discrete bulky aggregates with sizes up to several tens of micrometers. The adhesion of aggregates to the support probably decreased with increasing size and oversized aggregates fell away; none was found in SEM images of the samples obtained after prolonged reaction times. When Ni cations were present in the solution, they were incorporated preferentially into the LDH phase; an homogeneous layer was formed, with single platy crystals oriented perpendicular to the support. After calcination at 500°C, the products formed on Al2O3/Al support exhibited a shift of reduction maxima to higher temperatures in comparison with mixed oxides obtained by thermal decomposition of coprecipitated LDHs.

This study explores the impact that recent Bronze Age hoard finds have had on our understanding of hoarding practices across Britain and Northern Ireland. Changes to the legislation of Treasure and the onset of the Portable Antiquities Scheme in England and Wales have produced a wealth of new information on Bronze Age hoards. Beyond a handful of studies which have focused on specific groups of hoards or the distinction between dryland/wetland deposition, however, many of these more recent finds have been overlooked. Our regional understanding of hoarding practices across Britain is also largely based on studies which are now significantly out of date. This paper aims to address this problem by providing a snapshot of hoards and hoarding practices, based on a substantial dataset of 385 hoards (containing 7210 objects) that were reported on between 1997 and 2021. Broad chronological and spatial trends in the distribution are highlighted, with precedence given to characterising these enigmatic deposits based on their size and the categories of objects within them. This investigation provides fresh insights into the selection of certain object groups – particularly axes – during certain periods and within specific regions, whilst also exploring ideas so that we might better understand the scale of metalwork deposition. This research not only demonstrates how recent hoard finds fit into traditional narratives but also how they have the potential to enhance our understanding of regional hoarding practices, offering new and exciting avenues for future research.

Bronze and Early Iron Age hoards in Poland are the focus of a multi-faceted study combining archival research with laboratory analyses and landscape studies. The diverse dataset is expected to reveal new insights into the phenomenon of metal deposition.

This is the first comprehensive publication of the Knaresborough 1864 hoard of copper-alloy vessels and tools. A consideration of the circumstances of the hoard’s discovery, along with a biographical account of Thomas Gott (the man who deposited the hoard in the Yorkshire Museum), for the first time enables a case to be made for a findspot. A consideration of the vessels and other objects establishes the hoard as one of the most unusual assemblages of its kind from late Roman Britain. pXRF analysis of the vessels sheds light on their composition. Finally, a discussion of the hoard places it within the international context of late Roman deposition practices.

The evolution of midwater sediment plumes associated with deep-sea mining activities is investigated in the passive-transport phase using a simplified advection–diffusion-settling model. Key metrics that characterize the extent of plumes are defined based on a concentration threshold. Namely, we consider the volume flux of fluid that ever exceeds a concentration threshold, the furthest distance from and maximum depth below the intrusion where the plume exceeds the threshold, and the instantaneous volume of fluid in excess of the threshold. Formulas are derived for the metrics that provide insight into the parameters that most strongly affect the extent of the plume. The model is applied to a reference deep-sea mining scenario around which key parameters are varied. The results provide some sense of scale for deep-sea mining midwater plumes, but more significantly demonstrate the importance of the parameters that influence the evolution of midwater plumes. The model shows that the discharge mass flow rate and the concentration threshold play an equal and opposite role on setting the extent of the plume. Ambient ocean turbulence and the settling velocity distribution of particles play a lesser yet significant role on setting the extent, and can influence different metrics in opposing ways.

We develop and investigate an advection–diffusion-settling model of deep-sea mining collector plumes, building on the analysis of midwater plumes in Part 1. In the case of collector plumes, deposition plays a predominant role in controlling the mass of sediment in suspension, and thus on setting the extent of the plume. We first discuss the competition between settling, which leads to deposition, and vertical turbulent diffusion, which stretches the plume vertically and reduces deposition. The time evolution of the concentration at the seabed is found to be a highly nonlinear function of time that depends non-trivially on the ratio of diffusion to settling time scales. This has direct implications for the three extent metrics considered, namely the instantaneous area of the seabed where a deposition rate threshold is exceeded, the furthest distance from the discharge where the plume exceeds a concentration threshold and the volume flux of fluid in the water column that ever exceeds a concentration threshold. Unlike the midwater plume, the particle velocity distribution of the sediment has the greatest influence on the extent metrics. The turbulence levels experienced by the plume also markedly affects its extent. Expected variability of turbulence and particle settling velocity yields orders of magnitude changes in the extent metrics.

There is limited knowledge about the metabolism and function of n-3 very-long-chain PUFA (n-3 VLC-PUFA) with chain lengths ≥ 24. They are known to be produced endogenously in certain tissues from EPA and DHA and not considered to originate directly from dietary sources. The aim of this study was to investigate whether n-3 VLC-PUFA from dietary sources are bio-available and deposited in tissues of rat, fish and mouse. Rats were fed diets supplemented with a natural fish oil (FO) as a source of low dietary levels of n-3 VLC-PUFA, while Atlantic salmon and mice were fed higher dietary levels of n-3 VLC-PUFA from a FO concentrate. In all experiments, n-3 VLC-PUFA incorporation in organs was investigated. We found that natural FO, due to its high EPA content, to a limited extent increased endogenous production of n-3 VLC-PUFA in brain and eye of mice with neglectable amounts of n-3 VLC-PUFA originating from diet. When higher dietary levels were given in the form of concentrate, these fatty acids were bio-available and deposited in both phospholipids and TAG fractions of all tissues studied, including skin, eye, brain, testis, liver and heart, and their distribution appeared to be tissue-dependent, but not species-specific. When dietary EPA and DHA were balanced and n-3 VLC-PUFA increased, the major n-3 VLC-PUFA from the concentrate increased significantly in the organs studied, showing that these fatty acids can be provided through diet and thereby provide a tool for functional studies of these VLC-PUFA.

This paper critically evaluates how archaeologists define ‘grave goods’ in relation to the full spectrum of depositional contexts available to people in the past, including hoards, rivers and other ‘special’ deposits. Developing the argument that variations in artefact deposition over time and space can only be understood if different ‘types’ of find location are considered together holistically, we contend that it is also vital to look at the points where traditionally defined contexts of deposition become blurred into one another. In this paper, we investigate one particular such category – body-less object deposits at funerary sites – in later prehistoric Britain. This category of evidence has never previously been analysed collectively, let alone over the extended time period considered here. On the basis of a substantial body of evidence collected as part of a nationwide survey, we demonstrate that body-less object deposits were a significant component of funerary sites during later prehistory. Consequently, we go on to question whether human remains were actually always a necessary element of funerary deposits for prehistoric people, suggesting that the absence of human bone could be a positive attribute rather than simply a negative outcome of taphonomic processes. We also argue that modern, fixed depositional categories sometimes serve to mask a full understanding of the complex realities of past practice and ask whether it might be productive in some instances to move beyond interpretively confining terms such as ‘grave’, ‘hoard’ and ‘cenotaph’. Our research demonstrates that is it not only interesting in itself to scrutinize archaeological evidence that does not easily fit into traditional narratives, but that the process of doing so also sheds new light on the validity of our present-day categories, enabling deeper insights into how people in the past ordered their material and conceptual worlds. Whilst our main focus is later prehistoric Britain, the issues we consider are potentially relevant across all periods and regions.

A variable proportion of finds from the Neolithic and Chalcolithic of ‘Old Europe’ has come from places outside settlements, cemeteries, production sites, ritual sites, or caves. Such finds tend to be described as ‘chance/isolated/single/stray’ finds or, when in groups, as ‘hoards’. The frequent, modernist cause invoked for these finds is that they were either ‘hidden’ in times of mortal danger, represented a ‘gift to the gods’, or simply ‘lost’. One reason for these explanatory shortcomings is the over-attention to the types of objects deposited in the landscape and the frequent lack of attention to the often-distinctive place of deposition. We believe that we have misnamed, overlooked, or not accurately characterised an entire class of sites, which we term ‘landscape deposition sites’, whose defining feature was the transformation of a place by the deposition of a significant object or group of objects to create a qualitatively different place. The creation of such landscape deposit sites varied in time and space throughout Old Europe, but all sites were affected by this new dimension of the extended cultural domain.

In this article, we consider the interpretations of metal deposition in North-west Europe and the light they shed on an earlier and geographically different region. The primary aim of this paper is an exploration of the variable relationships between landscape deposit sites and the coeval finds made in special deposits in settlements and cemeteries in the 5th and 4th millennia bc, which will lead to proposed new interpretations of landscape deposition sites.

Gas turbine engines for fixed-wing or rotary-wing aircraft are operated in a variety of harsh weather environments ranging from arctic, volcanic zones, to desert conditions. Operation under these degraded conditions leads to the undesired entrainment of complex particulates resulting in drastic performance losses. Hence, there is a critical need to understand the governing mechanisms to inform the development of durable thermal and environmental barrier coatings. The objective of the current work is to present a novel multiscale physics-based approach to study two-phase flows that take into account the underpinning particle transport and deposition dynamics. Sessile droplet models are presented and used to compute the contact angle at high temperatures and compared with experiments. The study also investigates the sensitivity of deposition patterns to the Stokes number and the results identify local vulnerability regions. The analysis suggests that particle size distributions and the initial trajectories of the particles are critically important in predicting the final deposition pattern.

The perforated stone battle-axes and axe-hammers of Early Bronze Age Britain have been used either to interpret the status of individuals they were buried with or have been overlooked; this is especially the case with axe-hammers. Previous understandings have assumed battle-axes were purely ceremonial, while the rougher axe-hammers were neither functional nor prestigious, being too large and too crude to be prestige items. Studies of the 20th century were focused on creating a typology and understanding the manufacture and petrological sources of the stone, concluding that haphazard exploitation of stone was used to create a variety of different shapes of both implements. This paper revisits the question of how these artefacts were used. It presents the results of the first large-scale application of use-wear analysis to British Early Bronze Age battle-axes and axe-hammers, from northern Britain and the Isle of Man. Combining the results of the wear analysis with experimental archaeology and contextual analysis, it is argued that these objects were functional tools, some of which saw prolonged use that might have spanned multiple users. The evidence shows that the few implements found in burial contexts were both functional and symbolic; their inclusion in burial contexts drawing upon relational links which developed through the itineraries of these objects. It is also apparent that use and treatment were similar across all types of battle-axe and axe-hammer, with some regional variation in the deposition of axe-hammers in south-west Scotland. It is concluded that battle-axes and axe-hammers had varied and multiple roles and significances and that it is possible to discover what each artefact was used for by deploying a use-wear analysis methodology.

While Maya public rituals are often assumed to have developed from domestic practices, caches at Ceibal in Guatemala demonstrate the concurrent emergence of distinct domestic and public rituals. During the Middle Preclassic period (c. 1000–350 BC), caches in domestic areas were associated with construction phases—deposited on floors or within construction fills. In the public plaza, however, caches were deposited in intrusive pits. Later, domestic and public ritual practices became more similar. By focusing on deposition processes and deposit context, rather than content, it is possible to recognise distinct ritualised activities that are sometimes obscured by predefined categories such as ‘cache’.

Artificial islets, or crannogs, are widespread across Scotland. Traditionally considered to date to no earlier than the Iron Age, recent research has now identified several Outer Hebridean Neolithic crannogs. Survey and excavation of these sites has demonstrated—for the first time—that crannogs were a widespread feature of the Neolithic and that they may have been special locations, as evidenced by the deposition of material culture into the surrounding water. These findings challenge current conceptualisations of Neolithic settlement, monumentality and depositional practice, while suggesting that other ‘undated’ crannogs across Scotland and Ireland could potentially have Neolithic origins.

The exhumation history of mountain belts can be derived from radiometric dating of detrital mineral grains in proximal and distal post- and synorogenic sediments. The application of single-crystal dating techniques avoids the averaging effect that characterizes multi-grain and whole-rock techniques and allows the identification of populations of grains with distinct thermal histories. Of the major single crystal dating methods available, 40Ar/39Ar dating of detrital K-bearing minerals, in particular white mica, is perhaps the most versatile and widely applied technique. For a closure temperature of Ar of 350–400°C, muscovite 40Ar/39Ar ages record the time a rock mass passed through 8–10 km beneath actively eroding mountain belts. Detrital muscovit ages eroded from orogenic mountain belts have been used extensively to identify the provenance of sediments from source regions with distinct thermal histories, determine the history and rate of exhumation of the source region, and provide an upper limit on the sediment age. Here I review the principles of 40Ar/39Ar dating of detrital muscovite and illustrate the method with examples showing how the provenance and the thermal history of sediment source regions derived from such studies can be used to constrain the exhumation and tectonic history of orogenic belts.