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Together with research teams from around the world, the Anthropocene Working Group (AWG) has been meticulously quantifying and scrutinizing the global stratigraphic imprint of human activities, the results of which are gathered in this thematic collection of papers in The Anthropocene Review. How can such empirical research, which so impressively articulates the end of a relatively stable Earth System in the mid-20th century, inform our ways of understanding and responding to the planetary crisis that the geological samples quietly represent? In this afterword to the collection we report and reflect on the joint undertaking of the AWG, Haus der Kulturen der Welt and the Max Planck Institute for the History of Science to bring geoscientific evidence, cultural experimentation and historical contextualization together in a shared public framework.

We review and compare proposals for 12 reference sections submitted to the Anthropocene Working Group of the International Subcommission on Quaternary Stratigraphy, of which one will be recommended as the Global boundary Stratotype Section and Point (GSSP) to define the base of the Anthropocene as a series within the Geological Time Scale. The sites span five continents and are located in diverse environments, with all but one sampled by coring. Many sites show annually resolved laminae (here considered optimal for GSSP selection) that can be independently dated radiometrically to confirm a complete succession over the critical interval. An extensive range of proxies, documenting profound human modification of the Earth System at around the mid-20th century interval, has been analysed. Airborne signals (e.g. radioisotopes, fly ash, stable carbon and nitrogen isotopes) provide the most widespread and near-isochronous proxies, applicable across most environments. Additional means of correlation include the appearance of microplastics and persistent organic pollutants, and shifts in heavy metal concentrations and lead isotope ratios. Assemblage changes of microfossils (and some macrofossils) in marine, estuarine and lake settings reflect environmental changes and biological introductions. These systematic and comprehensive datasets, with correlation established between sections, provide the basis for a proposal to formalize the Anthropocene.

International audience; The Anthropocene was conceptualized in 2000 to reflect the extensive impact of human activities on our planet, and subsequent detailed analyses have revealed a substantial Earth System response to these impacts beginning in the mid-20 th century. Key to this understanding was the discovery of a sharp upturn in a multitude of global socioeconomic indicators and Earth System trends at that time; a phenomenon termed the 'Great Acceleration'. It coincides with massive increases in global human-consumed energy and shows the Earth System now on a trajectory far exceeding the earlier variability of the Holocene Epoch, and in some respects the entire Quaternary Period. The evaluation of geological signals similarly shows the mid-20 th century as representing the most appropriate inception for the Anthropocene. A recent mathematical analysis has nonetheless challenged the significance of the original Great Acceleration data. We examine this analytical approach and reiterate the robustness of the original data in supporting the Great Acceleration, while emphasizing that intervals of rapid growth are inevitably time-limited, as recognised at the outset. Moreover, the exceptional magnitude of this growth remains undeniable, reaffirming the centrality of the Great Acceleration in justifying a formal chronostratigraphic Anthropocene at the rank of series/epoch.

The human species has deeply impacted the geology of our planet, our current environmental conditions now being very different from the stable interglacial conditions of the Holocene Epoch, in which human civilization flowered. Hence, a new epoch has been proposed, the Anthropocene, starting in tandem with the mid-20th-century Great Acceleration of population, industrialization, and globalization. One of the clearest measures of human impact on our planet is energy use, as reflected by rapidly increasing atmospheric carbon dioxide levels. Through this lens, the large-scale historical patterns of human activity show not gradual change but sudden and massive linked changes to geology and ecosystems. This has been driven by growth of the technosphere, a quasi-autonomous and emergent sphere of human-driven processes that interacts with the other Earth spheres. Consequences include the rapid accumulation of unrecycled waste, increasingly threatening the success of this development and hence of humans too.

A San Francisco Estuary core was analysed at high resolution to assess its component stratigraphic signatures of the Anthropocene in the form of non-native species, Hg, spheroidal carbonaceous particles, δ13Corg, δ15N, radiogenic materials, and heavy metals. Time series analysis of the core using Ti data provides a chronology to depth 167 cm into the 1960s. Below this, to depth 230 cm, the lowermost part of the core may extend to the 1950s or potentially a little earlier. The earliest anthropogenic marker recorded in the core is the excursion in Hg (beginning at 190 cm) which may denote the early 1960s and is the closest stratigraphic marker in the core to the proposed mid-20th century timing for the onset of the Anthropocene. Biostratigraphical signatures of non-native species arriving in the 1970s–1980s are widespread key markers and are significant tools for the correlation of Anthropocene deposits across the estuary. The absence of signals that indicate pre-1950s deposits precludes the use of the core to mark the Holocene–Anthropocene boundary. However, the core provides an important reference section to demonstrate the palaeontological distinctiveness of Anthropocene series deposits.

Merritts et al. (2023) misrepresent Paul Crutzen's Anthropocene concept as encompassing all significant anthropogenic impacts, extending back many millennia. Crutzen's definition reflects massively enhanced, much more recent human impacts that transformed the Earth System away from the stability of Holocene conditions. His concept of an epoch (hence the ‘cene’ suffix) is more consistent with the strikingly distinct sedimentary record accumulated since the mid-20th century. Waters et al. (2022) highlighted a Great Acceleration Event Array (GAEA) of stratigraphic event markers that are indeed diverse and complex but also tightly clustered around 1950 CE, allowing ultra-high resolution characterization and correlation of a clearly recognisable Anthropocene chronostratigraphic base. The ‘Anthropocene event’ offered by Merritts et al., following Gibbard et al. (2021, 2022), is a highly nuanced concept that obfuscates the transformative human impact of the chronostratigraphic Anthropocene. Waters et al. (2022) restricted the meaning of the term ‘event’ in geology to conform with usual Quaternary practice and improve its utility. They simultaneously recognized an evidence-based Anthropogenic Modification Episode that is more explicitly defined than the highly interpretive interdisciplinary ‘Anthropocene event’ of Gibbard et al. (2021, 2022). The advance of science is best served through clearly developed concepts supported by tightly circumscribed terminology; indeed, improvements to stratigraphy over recent decades have been achieved through increasingly precise definitions, especially for chronostratigraphic units, and not by retaining vague terminology., Earth-Science Reviews, 238, ISSN:0012-8252, ISSN:1872-6828

The Mississippi River maintains commercial and societal networks of the USA along its >3700 km length. It has accumulated a fluvial sedimentary succession over 80 million years. Through the last 11,700 years of the Holocene Epoch, the wild river shaped the landscape, models of which have become classic in geological studies of ancient river strata. Studies of the river were led by the need to develop infrastructure and to search for hydrocarbons, through which, these models have become quite sophisticated. However, whilst the models demonstrate how the wild river behaves, a monumental shift in fundamental controls on the entire fluvial system, broadly coinciding with the proposed mid-20th century onset of the Anthropocene Epoch, has generated new geological patterns that are becoming globally ubiquitous, and which the Mississippi River typifies. As such, whilst classic Holocene river models may be compared to human-modified systems such as the Lower Mississippi River (and others worldwide), locally the models may now only directly apply to its fossilized components preserved in the sub-surface. Such river models need adapting to better understand the present dynamics, and future evolution of these landscapes.

This chapter focuses on the possibilities of restoring nature. It shows possibilities of cohabitation between the numerous human and rapidly shrinking wild ape populations, such as with the Orangutan Foundation preserving habitat, releasing orphaned orangutans in protected reserves, and promoting education and livelihoods for the locals. Rewilding and restoration need concerted efforts to accommodate natural landscapes and wild animal and plant populations, and to avert a mass extinction. The chapter explores, too, the possibility of building mutualistic ‘garden’ cities and rebuilding marine ecosystems such as those of mangrove and seagrass. For a sustainable future, the human and natural worlds need sensitive and imaginative rebalancing.

This chapter focuses on changing human understanding of life on Earth. It traverses the exploration of the Moon, the extinction of Neanderthals, and the hegemony achieved by Homo sapiens. Through observations ranging from Stone Age cave art to the Colosseum’s blood-drenched spectacles, the chapter discusses how human relations to animals seem to have evolved, with increasingly pervasive exploitation of animals and plants for food, power, and pleasure. The chapter then charts how scientific ideas of life of life have developed in biology and geology, from the early ideas of Aristotle and Lucretius, through Buffon and Humboldt, to the development of modern ideas of the biosphere through Vladimir Vernadsky and James Lovelock. Life is recognized as the key ingredient of the complex, self-regulating planet we call Earth.

This chapter looks into the geographic patterns of animals and plants. It highlights how the Wallace Line and other major biogeographical boundaries were discovered, as marking fundamental divisions between the animal and plant communities of Earth. It describes examples in Earth’s geological past when major communities mixed, as when North and South America joined. And it shows how these fundamental divisions are now dissolving worldwide, on the land and in the oceans, as neobiota or ‘introduced species’ have been transported by human activities, or have followed humans on their globe-trotting travels. This homogenization of life on Earth has reset the trajectory of Earth’s biological history, though also in some instances may help ecosystems cope better with the effects of climate change.

This chapter focusses on how energy intersects with life. The energy of sunlight has sustained life on Earth for billions of years, converted by plants into chemical energy, which in turn, is distributed through Earth’s myriad organisms. Now, humans have become adept at controlling energy sources for their own benefit, both by directing biological production towards themselves through crops and domesticated animals, and by opening up new sources of energy, including the fossilized sunlight of hydrocarbon fuels. One major development was the Haber-Bosch process, to fix (at great energetic cost) nitrogen from the air for the increased biological production that now keeps something like half the world’s population alive, via programmes like the Green Revolution. The Earth’s rapidly growing cities are now enormous energy sinks quite out of balance with natural systems, and the chapter concludes by discussing how they may be brought more into balance with nature.

This title explores the abundance and complexity of life on Earth, which—as we discover more of other planets—appears as a true oasis in the cosmos. Despite its diversity, life forms little more than a veneer on the planet, albeit one that has hugely influenced its climate and environment. Earth and its biosphere have profoundly changed through more than four billion years of time, undergoing a succession of transformations. Now, we are living through the latest of these, in which humans have become extraordinarily numerous at the expense of other living creatures, not least our kindred ape species that are in severe decline. A critical development is the technology upon which advanced human societies utterly depend, from which has emerged a technosphere that now rivals the biosphere in scale and power, and that is evolving with terrific speed. Among its unwanted side-effects are enormous and ongoing changes to the atmosphere, climate, land, and cycling of key elements for life. The biosphere is on the cusp of another transformation, and this book concludes by exploring ways in which we can influence this process for the better.

This chapter explores the diversity of life, introducing this through the teeming life found in soil. It traces the history of life, from the origin of all species as the Last Universal Common Ancestor (LUCA), some three to four billion years ago. This was a springboard to an astonishing diversity of microbes, revealed by Carl Woese who uncovered their genetic signatures. The much later diversification of multicellular organisms in the sea, and its yet later expansion on to land, have been revealed by palaeontologists, and interpreted through the revolutionary studies of Jack Sepkoski, Stephen Jay Gould, and Mike Benton; possible reasons for their very different patterns of diversification are outlined.

This chapter explores the livestock living on Earth through the phenomenon of fast-food chains and hamburgers across the world. Cattle, sheep, pigs, goats, and other domesticated animals now far outweigh the Earth’s wild animals, while the many billions of chicken consumed by humans are by far the Earth’s most numerous bird. This unprecedented distortion of the Earth’s food web extends to the oceans, as overfishing has decimated fish populations, and aquaculture—with its own ecological costs—spreads rapidly across the world. The chapter ends by exploring means of relieving this intense ecological pressure, with potential solutions, ranging from eating less meat, to technological solutions for growing more food.

This chapter discusses the development of technology and how it intersects with the biosphere. Technology was originally ingenious and artisanal, but limited for want of energy and resources. Then, coal, oil, and gas became energy sources. Technology mushroomed into a planet-spanning technosphere, currently parasitizing and diminishing the biosphere, with ballpoint pens and Swan lightbulbs among a myriad of rapidly evolving technospecies. While, as the technosphere develops and proliferates, it now begins to include living machines such as xenobots. The technosphere, while now similarly sized to the biosphere, is far more wasteful of resources. If its evolution is not to cause the Earth to become one giant landfill site, it must quickly become much better at recycling.

This chapter opens with Earth’s gigantic animals, many of which we only know from museum specimens, not only because of ancient extinction events, but because the megafauna of the Ice Ages were among the first to be widely exterminated by human hunting. This has had profound impacts on the Earth’s ecosystems because of these animals’ important role in controlling vegetation patterns. Island extinctions are covered too, both on land with examples such as the Rodrigues Solitaire bird, and increasingly beneath the sea, with seamount communities now threatened by plans for deep-sea mining. The patterns of the great prehistoric mass extinction events are explored, and it is shown how some extinctions—of the rare velvet worms, for instance—might have an evolutionary impact belying their small numbers. The chapter ends by discussing how some of these worrying trends might be halted, at large scales with rewilding, and also at smaller scales, in our own gardens.

Event stratigraphy is used to help characterise the Anthropocene as a chronostratigraphic concept, based on analogous deep-time events, for which we provide a novel categorization. Events in stratigraphy are distinct from extensive, time-transgressive ‘episodes’ – such as the global, highly diachronous record of anthropogenic change, termed here an Anthropogenic Modification Episode (AME). Nested within the AME are many geologically correlatable events, the most notable being those of the Great Acceleration Event Array (GAEA). This isochronous array of anthropogenic signals represents brief, unique events evident in geological deposits, e.g.: onset of the radionuclide ‘bomb-spike’; appearance of novel organic chemicals and fuel ash particles; marked changes in patterns of sedimentary deposition, heavy metal contents and carbon/nitrogen isotopic ratios; and ecosystem changes leaving a global fossil record; all around the mid-20th century. The GAEA reflects a fundamental transition of the Earth System to a new state in which many parameters now lie beyond the range of Holocene variability. Globally near-instantaneous events can provide robust primary guides for chronostratigraphic boundaries. Given the intensity, magnitude, planetary significance and global isochroneity of the GAEA, it provides a suitable level for recognition of the base of the Anthropocene as a series/epoch. Contributing authors are members of the Anthropocene Working Group (AWG), of the Subcommission on Quaternary Stratigraphy (SQS), a component body of the International Commission on Stratigraphy (ICS). The paper was inspired by a publication by Gibbard et al. (2021), which initiated our critical enquiry into the Anthropocene as a geological event. The authors thank the anonymous referees and editor, Alessandra Negri, whose comments helped improve this manuscript. We are also grateful to Lucy E. Edwards for alerting us at the proof stage to the NASC requirements for defining episodes formally

As part of an international effort to evaluate potential replacement sections for the current Aeronian GSSP, the stratigraphy of the Rheidol Gorge section (central Wales, UK) is being restudied. A total of 28 samples from the Rhuddanian-Aeronian boundary interval at Rheidol Gorge were studied for chitinozoans. This famous Welsh Basin section, its stratigraphy rooted in the work of O.T. Jones and M. Sudbury, comprises a series of laminated black shales with abundant graptolites, alternating with grey mudstone intervals, deposited in anoxic to dysoxic/oxic seafloor conditions, respectively. The exposed section of c. 20 m spans the middle part of the upper Rhuddanian Pernerograptus revolutus Biozone through the lower Aeronian Neodiplograptus magnus Biozone of the lower to mid-Llandovery Series (Cwmere and Derwenlas formations). Our chitinozoan analysis yielded an assemblage of over 2300 specimens distributed approximately uniformly throughout the entire succession. A total of 16 different taxa are identified, of which 12 remain in open nomenclature, reflecting the poor to moderately intact preservation of the specimens. Based on the presence of key species such as Spinachitina maennili and Conochitina iklaensis, the Rheidol Gorge section is referred to the Spinachitina maennili Biozone. This observation is in perfect alignment with the typical signature of other Rhuddanian-Aeronian boundary successions in the Welsh Basin and in other parts of the world.

The Anthropocene as a concept originated in 2000, suggested by Paul Crutzen in an Earth System science context. Only later was it considered as a putative geological series, including in GTS2012 (Zalasiewicz et al. 2012). This was barely three years after the establishment of the Anthropocene Working Group (AWG), tasked by the Subcommission on Quaternary Stratigraphy to examine the Anthropocene for potential inclusion in the GTS and to formulate a definition. In GTS2012 a likely generalised stratigraphic signature was postulated to comprise: a) lithostratigraphic signals, both direct modification of the landscape and indirect influences on sedimentary facies through rapidly modifying drivers; b) sequence stratigraphic signals due to modern sea-level rises, envisaging a near-future marine transgression; c) biostratigraphic signals through increased extinction rates, range changes especially through unprecedented rates of species invasions; and d) chemostratigraphic signals including inorganic and organic contaminants, isotopic shifts of carbon and nitrogen and fallout from nuclear bomb testing. By the time of GTS2020 (Zalasiewicz et al. 2020), not only could specific examples of temporal variations in many of these proxies be demonstrated, but also numerous new proxies, such as inorganic crystalline mineral-like compounds, microplastics, fuel ash and black carbon had been demonstrated and more information was available on the scale of human terraforming of landscape and anthropogenic modification of river systems. Further, the intervening eight years had seen a strengthening of the evidence of climate warming, sea-level rise and ocean acidification.In GTS2012, three levels for the beginning of the Anthropocene were considered: the Early Holocene; the onset of the Industrial Revolution; and the mid-20th century, and only the first option was definitively excluded. GTS 2020 was able to report the findings of the AWG that the Anthropocene represented “geological reality”, was best considered at epoch level, should be linked with the plethora of proxies that initiate or show marked perturbations at around the 1950s and is best defined using a GSSP. In GTS2020, the ongoing task of researching potential GSSP candidate sections for the Anthropocene Series was also outlined and this work is anticipated to be completed by 2022. The eleven current sites encompass diverse environments that will best preserve the extensive range of proxies suitable for characterising the prospective Holocene–Anthropocene transition. All sections will be in borehole/drill cores, most showing annually resolved laminations that can be independently dated radiometrically to confirm a complete succession extending back to pre-Industrial times. The strengths and weaknesses of distinct environments are discussed in GTS2020 for lake deposits, marine anoxic basins, estuaries and deltas, speleothems, glacial ice, coral reefs, trees and peat. The evidence collected already suggests that the Anthropocene may be widely recognised and delineated as a sharply distinctive chronostratigraphic unit reflecting major Earth System change that will have geologically lasting consequences.Zalasiewicz, J., Crutzen, P.J. & Steffen, W. 2012. Chapter 32: The Anthropocene. The Geologic Time Scale 2012. https://doi.org/10.1016/B978-0-444-59425-9.00032-9 Zalasiewicz, J., Waters, C. & Williams, M. 2020. Chapter 31: The Anthropocene. The Geologic Time Scale 2020. https://doi.org/10.1016/B978-0-12-824360-2.00031-0

The Middle Pleistocene Subseries and Chibanian Stage were officially defined in 2020 through ratification of the Global Boundary Stratotype Section and Point (GSSP) at Chiba, Japan (Suganuma et al., in press). Their shared base at 774.1 ka represents the approximate midpoint of the Early–Middle Pleistocene transition, a 1.4–0.4 ka interval marked by a progressive increase in the amplitude of climate oscillations and shift towards a quasi-100 ky frequency. They currently both extend to the base of the Upper Pleistocene Subseries dated provisionally at ~129 ka (Head et al., in press). Global stages have not traditionally been employed for the Quaternary owing to the long use of global subseries and regional stages. Global stages are nonetheless required for formal subdivision of the International Chronostratigraphic Chart, and their acceptance in subdividing both the Holocene and Pleistocene Series has become increasingly evident. The Middle Pleistocene Subseries and Chibanian Stage are currently identical in extent. With this in mind, we consider the possibility of subdividing the Middle Pleistocene by introducing a second stage, which would shorten the duration of the Chibanian and increase its utility. There has been increasing recognition of the ‘Mid-Brunhes Event’ (Jansen et al., 1986) more recently termed the ‘mid- Brunhes Transition’ (Yin, 2013; Barth et al., 2018), an abrupt step-change to increased amplitude of the quasi-100 kyr cycles and warmer interglacials from MIS 11 onwards. The base of this new stage would reasonably be placed around the MIS 12–MIS 11 transition (Termination V, ~420 ka), a level clearly recognised in the marine record. This level appears to approximate the bases of the Holsteinian, Hoxnian, Likhvinian, and Zavadivian regional stages across northwestern and central Europe, the Russian Plain, and the Ukrainian Loess Plain; and can be traced across the Chinese Loess Plateau (Cohen and Gibbard, 2020). The possibility of a second stage will initially be explored by publication of a position paper. If this attracts sufficient support, a Working Group of the International Subcommission on Quaternary Stratigraphy will be established to analyse the case more formally.Barth, A.M., Clark, P.U., Bill, N.S., He, F., Pisias, N.G., 2018. Climate evolution across the Mid-Brunhes Transition. Climate of the Past 14, 2071–2087.Cohen, K., Gibbard, P., 2020. Global chronostratigraphical correlation table for the last 2.7 million years v.2019 (Poster version), Mendeley Data, V3, doi: 10.17632/dtsn3xn3n6.3Head, M.J., Pillans, B., Zalasiewicz, J.A., in press. Formal ratification of subseries/subepochs for the Pleistocene Series/Epoch of the Quaternary System/Period. Episodes.Jansen, J.H.F., Kuijpers, A., Troelstra, S.R., 1986. A mid-Brunhes climatic event: Long-term changes in global atmosphere and ocean circulation. Science 232, 619–622.Suganuma, Y., Okada, M., Head, M.J. et al., in press. Formal ratification of the Global Boundary Stratotype Section and Point (GSSP) for the Chibanian Stage and Middle Pleistocene Subseries of the Quaternary System: the Chiba Section, Japan. Episodes.Yin, Q., 2013. Insolation-induced mid-Brunhes transition in Southern Ocean ventilation and deep-ocean temperature. Nature 494: 222–225.

The Holocene and Pleistocene series/epochs have each long been divided into Early, Middle and Late subseries/subepochs, although their formalization had been complicated by the hitherto absence of this rank from the International Chronostratigraphic Chart. On 14th June 2018, the Holocene was formally subdivided into the Greenlandian, Northgrippian and Meghalayan stages/ages and their corresponding Lower/Early, Middle, Upper/Late subseries/subepochs, each defined by a Global Boundary Stratotype Section and Point (GSSP). The GSSP for the lowermost stage, the Greenlandian, is that of the Holocene as previously defined in the NGRIP2 Greenland ice core, and dated at 11,700 yr b2k (before 2000 CE). The GSSP for the Northgrippian is in the NGRIP1 Greenland ice core, and dated at 8236 yr b2k, whereas that for the Meghalayan is located in a speleothem from Mawmluh Cave, Meghalaya, northeast India with a date of 4250 yr b2k (Walker et al., 2018). The Pleistocene Series/Epoch of the Quaternary System/Period has been divided unofficially into three subseries/subepochs since at least the 1870s. On 30th January 2020, two proposals were ratified: 1) the Lower Pleistocene Subseries, comprising the Gelasian Stage and the superjacent Calabrian Stage, with a base defined by the GSSP for the Gelasian Stage, the Pleistocene Series, and the Quaternary System, and currently dated at 2.58 Ma; and 2) the term Upper Pleistocene, at the rank of subseries, with a base currently undefined but provisionally dated at ~129 ka. The Middle Pleistocene and its corresponding Chibanian Stage/Age had meanwhile been formalized on January 17, 2020 with a GSSP in the Chiba section, Japan. The GSSP is placed 1.1 m below the directional midpoint of the Matuyama–Brunhes Chron boundary, at the base of a regional lithostratigraphic marker, the Ontake-Byakubi-E tephra bed, in the Chiba section. The GSSP has an astronomical age of 774.1 ka and is placed just below the top of Marine Isotope Substage 19c. These ratifications nominally complete the official division of the Quaternary into subseries/subepochs, although the Upper Pleistocene and its corresponding stage remain to be defined by GSSP. The Anthropocene is currently an unofficial unit, while analysis of potential candidate GSSP locations is progressing in preparation for a formalization proposal. If approved, it would terminate the Holocene at around the year 1952, assuming it is defined at series/epoch rank.Head, M.J., Pillans, B., and Zalasiewicz, J.A., in press. Formal ratification of subseries/subepochs for the Pleistocene Series/Epoch of the Quaternary System/Period. EpisodesSuganuma, Y., Okada, M., Head, M.J., et al., in press. Formal ratification of the Global Boundary Stratotype Section and Point (GSSP) for the Chibanian Stage and Middle Pleistocene Subseries of the Quaternary System: the Chiba Section, Japan. EpisodesWalker, M., Head, M.J., Berkelhammer, M. et al., 2018. Formal ratification of the subdivision of the Holocene Series/Epoch (Quaternary System/Period): two new Global Boundary Stratotype Sections and Points (GSSPs) and three new stages/subseries. Episodes 41(4): 213–223.

Modification of ecosystems through the introduction of non-native species (neobiota) is one part of the major human impact on the biosphere. Neobiota are now present worldwide and often significantly outnumber native fauna and flora. In many places they have left a distinctive biostratigraphic record of anthropogenic changes to the biosphere in the 20th century. Few ecosystems have been as severely affected by the arrival of neobiota as San Francisco Bay. Some 234 introduced species comprising up to 97% of individuals and in some places up to 99% of the biomass are known to be present in the bay (Cohen and Carlton, 1998). Among the multitude of neobiotic species established are Trochammina hadai, a benthic foraminifer that is native to Japan and was introduced in 1983 (McGann 2008), and Potamocorbula amurensis, a bivalved mollusc native to the Amur River region of East Asia that was introduced in 1986 (Carlton et al. 1990). Here we present sediment core data showing the arrival and proliferation of T. hadai and P. amurensis in addition to three introduced ostracod species, Spinileberis quadriaculeata, Eusarsiella zostericola and Bicornucythere bisanensis. The introduction of T. hadai is thought to have occurred through ballast water exchange from trans-Pacific shipping, and has produced a major perturbation to the foraminiferal record of San Francisco Bay. Pb-210 radiometric dating has established a high-resolution chronology for the core and analysis of fly ash particles (Rose 2015) emitted from coal-fired power stations allow time horizons, and the chronologies they define, to be correlated to a further 18 cores collected across the bay. This quantifies both the temporal and spatial extent of a human-induced biostratigraphic assemblage of neobiota, one that is correlatable with a biostratigraphic record of changes to ecosystems across the world in the late 20th century. Carlton, J.T., Thompson, J.K., Schemel, L.E. and Nichols, F.H. 1990. Remarkable invasion of San Francisco Bay (California, USA), by the Asian clam Potamocorbula amurensis. I. Introduction and dispersal. Marine Ecology Progress Series, 81-94.Cohen, A.N. & Carlton, J.T. 1998. Accelerating invasion rate in a highly invaded estuary. Science 279, 555-558.McGann, M. 2008. High-resolution foraminiferal, isotopic, and trace element record from Holocene estuarine deposits of San Francisco Bay, California. Journal of Coastal Research 24, 1092-1109.Rose, N.L. 2015. Spheroidal carbonaceous fly ash particles provide a globally synchronous stratigraphic marker for the Anthropocene. Environmental Science & Technology 49, 4155-4162.

Two new graptolite assemblages are identified from discrete intervals within the Phu Ngu Formation, Na Ri District, Bac Kan Province, north-east Vietnam. The graptolites occur in laminated mud/siltstones thought to be distal turbidite deposits. A low-diversity diplograptid sensu lato assemblage occurs in mud-rich layers that are interlaminated with silty and sandy horizons containing the dendroid graptolite Dictyonema sp. This level also contains orthoconic nautiloids and conulariids. A few metres stratigraphically above, a second more diverse graptolite assemblage comprises a single Dicellograptus, tentatively identified as D. flexuosus, together with Climacograptus dorotheus and Orthograptus truncatus pauperatus in mud and silt laminae that also yield brachiopods, orthoconic nautiloids, conulariids, fragmentary trilobites, and ostracods. The ostracods include the first East Asian occurrence of the typically Baltic genus Kinnekullea, and we describe the new species Kinnekullea gaia. The graptolites suggest a Late Ordovician Katian age, most probably in the Dicranograptus clingani Biozone, this being older than previous biostratigraphical constraints on the Phu Ngu Formation.

International audience; The term Anthropocene initially emerged from the Earth System science community in the early 2000s, denoting a concept that the Holocene Epoch has terminated as a consequence of human activities. First associated with the onset of the Industrial Revolution, it was then more closely linked with the Great Acceleration in industrialization and globalization from the 1950s that fundamentally modified physical, chemical, and biological signals in geological archives. Since 2009, the Anthropocene has been evaluated by the Anthropocene Working Group, tasked with examining it for potential inclusion in the Geological Time Scale. Such inclusion requires a precisely defined chronostratigraphic and geochronological unit with a globally synchronous base and inception, with the mid-twentieth century being geologically optimal. This reflects an Earth System state in which human activities have become predominant drivers of modifications to the stratigraphic record, making it clearly distinct from the Holocene. However, more recently, the term Anthropocene has also become used for different conceptual interpretations in diverse scholarly fields, including the environmental and social sciences and humanities. These are often flexibly interpreted, commonly without reference to the geological record, and diachronous in time; they often extend much further back in time than the mid-twentieth century. These broader conceptualizations encompass wide ranges and levels of human impacts and interactions with the environment. Here, we clarify what the Anthropocene is in geological terms and compare the proposed geological (chronostratigraphic) definition with some of these broader interpretations and applications of the term "Anthropocene," showing both their overlaps and differences. Plain Language Summary The Anthropocene concept, that modern human impacts on Earth have been sufficient to bring in a new geological epoch, is only two decades old. In that short time, its use has grown explosively, not only in the Earth sciences but also far more widely to spread through the sciences generally, to spill over into the social sciences, arts, and humanities. This has led to welcome discussions between diverse scholarly communities, though also to some very different interpretations of the Anthropocene, when interpreted through different disciplinary lenses. Notably, the geological ZALASIEWICZ ET AL.

‘Hidden volcanoes’ highlights ancient volcanoes, which offer crucial perspectives that would not be clear from the study of modern volcanoes alone. Exhumed (uplifted and dissected) volcanoes provide vital glimpses deep inside a volcano, including how they work. They are windows showing what really happens when hot magma interacts with bedrock, ice-sheets, lakes, and deep oceans. Ancient volcanoes also reveal how volcanic processes vary with time. They have enabled us to discover new and awesome styles of eruption. Examples are described, from the highest mountain in Wales, Yr Wyddfa, or Snowdon, which was an explosive caldera volcano that emerged from shallow seas. Also described are ‘Large igneous provinces’, diamond-bearing volcanoes, and the most ancient volcanism on Earth.

‘The making of magma’ discusses the formation of magma. Volcanism is driven by prodigious amounts of heat from deep inside the Earth that partly melts rock to form magma, which accumulates and evolves deep underground, and may drive powerful eruptions that expel ash and lava on to the surface, creating a volcano. This process can be studied by inferences based upon volcano behaviour, seismic information, chemical tracers in volcanic materials, experimentation, and other clues. From enormous, diffuse networks deep in the Earth, the magma rises and gathers together in the crust as a complex system of interconnected fractures, reservoirs, and conduits. These magma reservoirs can be detected by seismic imaging.

‘How do volcanoes explode?’ examines how volcanoes explode, looking at the anatomy of an explosive eruption. It studies pumice-forming rhyolitic eruptions. One of the first things a volcanologist may do on arrival at a volcano is to figure out how the volcano has behaved in the past: what sort of eruptions, how large, and how frequent. Basaltic explosivity can be compared with rhyolitic and andesitic explosivity. Phoenix plumes rise from pyroclastic currents and contain mostly fine ash.

‘Volcanoes beyond Earth’ highlights volcanoes on other planets. There are many more volcanoes on Venus than there are on Earth, and many remain active. In the absence of plate tectonics and the kind of tectonic forces that raise Earth-style mountain belts, and of streams, rivers, and shorelines, it is volcanism and volcanic products that dominate the surface of this planet. Fossil volcanism occurs in the Moon, Mercury, and Mars; Io, the hypervolcanic moon of Jupiter; and the ice volcanoes of the Solar System. There is potential for volcanism on exoplanets within distant planetary systems.

Volcanoes: A Very Short Introduction explains how volcanoes work and how volcanologists forensically decipher the processes involved. Volcanic eruptions are amongst the most dramatic expressions of the powerful tectonic forces at work in the Earth beneath our feet. However, volcanism encompasses much more than just volcanoes themselves. On a planetary scale, it is an indispensable heat release mechanism; shaping landscapes, releasing gases into the atmosphere, and allowing the conditions for life on Earth. Thus, this VSI also considers how volcanoes interact with other physical processes on the Earth, with life, and with human society.

‘Making and breaking volcanoes’ addresses how volcanoes are constructed and denuded and explains the shape of volcanoes and their internal architecture, including the differences between scoria cones, tuff rings, maars, and dome fields, shield volcanoes, and stratocones. Some volcanoes (‘monogenetic’ volcanoes) erupt just once, whereas others (‘polygenetic’ volcanoes) may continue erupting intermittently for millions of years. When sufficient magma is rapidly expelled from the shallow reservoirs beneath the volcano the overlying ground is left unsupported and collapses, creating a large topographic basin known as a caldera. As the caldera founders, its steep sides, formed so abruptly, are unstable and collapse inwards as a series of landslides. Tall volcanoes tend to collapse sideways in giant landslides, then grow and collapse again. Rain and meltwater also wears away volcanoes, forming lahars and floods, and choking drainage systems.

‘Volcanoes, climate, and the biosphere’ explores how volcanism has perturbed both climate and the complement of living organisms on Earth, both locally and globally. Volcanic outbursts, depending on their nature and scale, may cause global warming or global cooling. In the historical record, even geologically modest eruptions have had dramatic repercussions. Volcanoes can affect local weather. It is possible that climate change can, in turn, affect volcanism.

‘What have volcanoes done for us?’ outlines how humans have benefited from volcanoes. Volcanism has helped make the planet as it is today, by contributing to the chemical composition of the atmosphere and oceans. Volcanoes provide rich, fertile environments for wildlife and agriculture. Ultimately, volcanoes have been essential for the evolution of the biosphere, the emergence of humanity and human civilization, and for the flowering of culture. However, volcanoes across the world are increasingly being exploited for tourism, quarrying, deforestation, and urbanization. They also pose a hazard, one that increases as burgeoning human populations encroach ever closer. The chapter then looks at methods of monitoring and mitigating volcanic hazards.

‘Volcanoes and water’ assesses how water affects the behaviour of volcanoes. When rising hot magma encounters groundwater, as in a water-saturated sandstone, the pore water in the sandstone next to the magma flashes to steam, and the force of the expanding steam within the rock tears the sand grains apart from each other, and streams them away as it escapes. Peperite, ‘phreatic’ (steam) eruptions, phreatomagmatic eruptions, submarine eruptions, emergent Surtseyan eruptions, and ‘phreatoplinian’ eruptions are thought to be the most violent on Earth. Glacial volcanoes, and catastrophic watery ‘lahars’ accompany many eruptions.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.