Paolo Tarolli
email: paolo.tarolli@unipd.it

Wenfang Cao

Giulia Sofia

Damian Evans

Erle C Ellis

From features to fingerprints: A general diagnostic framework for anthropogenic geomorphology

Keywords: Geomorphology, Anthropocene, landscapes, society, earth, humans, history, archaeology, remote sensing

Human societies have been reshaping the geomorphology of landscapes for thousands of years, producing anthropogenic geomorphic features ranging from earthworks and reservoirs to settlements, roads, canals, ditches and plough furrows that have distinct characteristics compared with landforms produced by natural processes. Physical geographers have long recognized the widespread importance of these features in altering landforms and geomorphic processes, including hydrologic flows and stores, to processes of soil erosion and deposition. In many of the same landscapes, archaeologists have also utilized anthropogenic geomorphic features to detect and analyse human societal activities, including symbolic formations, agricultural systems, settlement patterns and trade networks. This paper provides a general framework aimed at integrating geophysical and archaeological approaches to observing, identifying and interpreting the full range of anthropogenic geomorphic features based on their structure and functioning, both individually and as components of landscape-scale management strategies by different societies, or "sociocultural fingerprints". We then couple this framework with new algorithms developed to detect anthropogenic geomorphic features using precisely detailed three-dimensional reconstructions of landscape surface structure derived from LiDAR and computer vision photogrammetry. Human societies are now transforming the geomorphology of landscapes at increasing rates and scales across the globe. To understand the causes and consequences of these transformations and contribute to building sustainable futures, the science of physical geography must advance towards empirical and theoretical frameworks that integrate the natural and sociocultural forces that are now the main shapers of Earth's surface processes.

Introduction

Before humans left their first footprints on African landscapes, Earth's terrestrial surface was shaped solely by the natural geophysical processes of climate, tectonic uplift, volcanism and the erosion, transport and deposition of sediments, modified only by the ecosystem engineering activities of microbes, plants and animals [START_REF] Erwin | Macroevolution of ecosystem engineering, niche construction and diversity[END_REF]. While these processes continue to operate, human societies have increasingly gained the capacity to act as a novel force of geomorphic change, both adding to and interacting with pre-existing natural biogeophysical forces in shaping landscapes through activities ranging from the clearing of land using fire and the tillage of soils for agriculture, to the construction of settlements, dams, mines, canals, roads and other infrastructures [START_REF] Brown | The geomorphology of the Anthropocene: Emergence, status and implications[END_REF][START_REF] Cuff | Anthropogeomorphology[END_REF][START_REF] Dixon | Ozymandias in the Anthropocene: The city as an emerging landform[END_REF][START_REF] Edgeworth | The relationship between archaeological stratigraphy and artificial ground and its significance in the Anthropocene[END_REF][START_REF] Edgeworth | Diachronous beginnings of the Anthropocene: The lower bounding surface of anthropogenic deposits[END_REF][START_REF] Ellis | Ecology in an anthropogenic biosphere[END_REF][START_REF] Ellis | Earth science in the Anthropocene: New epoch, new paradigm, new responsibilities[END_REF][START_REF] Foley | Lithic landscapes: Early human impact from stone tool production on the Central Saharan Environment[END_REF][START_REF] Goudie | The human impact in geomorphology -50 years of change[END_REF][START_REF] Goudie | Geomorphology in the Anthropocene[END_REF][START_REF] Guthrie | The catastrophic nature of humans[END_REF][START_REF] Hooke | Land transformation by humans: A review[END_REF][START_REF] Kirch | Archaeology and global change: The Holocene Record[END_REF][START_REF] Lewis | Geological evidence for the Anthropocene[END_REF][START_REF] Sauer | The morphology of landscape[END_REF][START_REF] Tarolli | High-resolution topography for understanding Earth surface processes: Opportunities and challenges[END_REF][START_REF] Tarolli | Humans and the Earth's surface[END_REF][START_REF] Tarolli | Human topographic signatures and derived geomorphic processes across landscapes[END_REF][START_REF] Tarolli | Terraced landscapes: From an old best practice to a potential hazard for soil degradation due to land abandonment[END_REF][START_REF] Tarolli | The geomorphology of the human age[END_REF][START_REF] Waters | The Anthropocene is functionally and stratigraphically distinct from the Holocene[END_REF][START_REF] Zalasiewicz | Scale and diversity of the physical technosphere: A geological perspective[END_REF]. As a result, a complete assessment and understanding of the formation and evolution of Earth's current landforms requires a robust theoretical understanding of the anthropogenic processes that have assisted in shaping them.

The science of physical geography and that of geomorphology, in particular, requires new tools and frameworks capable of identifying and interpreting anthropogenic geomorphic features together with the sociocultural processes that have shaped them [START_REF] Ellis | Physical geography in the Anthropocene[END_REF]. The goal here is to help advance such a framework by connecting existing theories on human sociocultural processes with the observational techniques needed to identify the full spectrum of geomorphic products of these processes, both as individual "anthropogenic features" and their diagnostic interpretation as the geomorphic "sociocultural fingerprints" produced across landscapes by specific human societies. To do this, we integrate archaeological, ecological and geophysical frameworks around theory on sociocultural niche construction [START_REF] Ellis | Ecology in an anthropogenic biosphere[END_REF][START_REF] Ellis | Evolving the Anthropocene: Linking multi-level selection with long-term social-ecological change[END_REF], building on existing published work on anthropogenic geomorphology [START_REF] Brown | The geomorphology of the Anthropocene: Emergence, status and implications[END_REF][START_REF] Goudie | Geomorphology in the Anthropocene[END_REF][START_REF] Johnson | An observational and theoretical framework for interpreting the landscape palimpsest through airborne LiDAR[END_REF][START_REF] Li | A review on anthropogenic geomorphology[END_REF]Szabo, 2010;[START_REF] Tarolli | Human topographic signatures and derived geomorphic processes across landscapes[END_REF][START_REF] Tarolli | The geomorphology of the human age[END_REF].

Anthropogenic landscapes are sociocultural palimpsests

While many species alter their environments, humans are Earth's ultimate ecosystem engineers, engaging in a broader range of more potent environment-modifying behaviours than any other species [START_REF] Smith | Niche construction and the behavioral context of plant and animal domestication[END_REF][START_REF] Smith | The onset of the Anthropocene[END_REF]. By engineering environments using fire, tools of increasingly complex design and domesticated species, and by harnessing non-human energy to accomplish these modifications, human niche construction practices have radically enhanced the adaptive fitness of human individuals, social groups and societies, enabling human societies to increase in scale and to extend their reach across Earth's terrestrial surface [START_REF] Ellis | Ecology in an anthropogenic biosphere[END_REF][START_REF] Ellis | Evolving the Anthropocene: Linking multi-level selection with long-term social-ecological change[END_REF]. Most importantly, human capacities to engineer environments are not biological, but sociocultural, and these sociocultural capacities have evolved and accumulated over time together with human capacities for cooperation and social learning [START_REF] Ellis | Ecology in an anthropogenic biosphere[END_REF][START_REF] Ellis | Evolving the Anthropocene: Linking multi-level selection with long-term social-ecological change[END_REF] (Figure 1).

Human sociocultural niche construction has diversified, scaled up and utilized increasing amounts of energy over millennia, from the first use of fire to clear land (for greater success in hunting and foraging), to the construction and management of agricultural landscapes using animal labour, to urban settlements powered by fossil fuels, to the global networks of exchange infrastructure that have made contemporary human societies the most interdependent in history and have made humanity a global force of nature (Figure 1).

Human modification of landscapes has tended to increase in scale and complexity together with the scale and complexity of human societies [START_REF] Ellis | Ecology in an anthropogenic biosphere[END_REF]. By the Late Pleistocene, opportunistic use of naturally occurring fire was supplemented by technologies of fire maintenance and fire-making [START_REF] Sandgathe | Fire and the genus Homo: An introduction to supplement 16[END_REF], amplifying the ability of humans to transform ecosystems and the erosive and hydrologic processes accompanying land clearing over extensive areas, either intentionally or unintentionally. The construction of settlements by sedentary hunter-gatherers and early farmers left more robust geomorphic evidence due to the systematic and deliberate reconfiguration of landscapes, often reflecting distinctive patterns in social behaviour and material culture [START_REF] Fletcher | Low-density, agrarian-based urbanism: A comparative view[END_REF]. As societies scaled up over time, into the first agricultural, urbanized and then industrial societies, their ecosystem engineering also increased in scale, complexity, durability and in the sheer amounts of material moved (Figure 1). Ellis, 2015, Figure 3 andEllis et al., 2018, Figure 1). Even more significant complexity in anthropogenic landforms has emerged over time, as the geomorphic features engineered in support of one society have come to be inherited by, overlaid by, overwritten and reconstructed by later societies, such that the anthropogenic features and landforms of regions with sustained human occupation represent not the directed efforts of a single society, but rather the complex sociocultural palimpsests of multiple diverse societies [START_REF] Bailey | Time perspectives, palimpsests and the archaeology of time[END_REF]. Moreover, given that natural geomorphic processes continue to act during and after societal processes, the landform palimpsests of anthropogenic landscapes represent the sustained interplay of sociocultural and biogeophysical processes over time [START_REF] Johnson | An observational and theoretical framework for interpreting the landscape palimpsest through airborne LiDAR[END_REF].

Anthropogenic features and sociocultural fingerprints

Individual anthropogenic features, as specific human modifications of land surfaces such as an individual graves, buildings or roads, show a wide variety of forms. In aggregate, however, the anthropogenic features produced by a given society may evince a degree of consistency within a given sociocultural milieu, as illustrated in Figure 1. Thus, as archaeologists have long recognized, the material cultures of different societies pattern the surface of Earth in specific ways that produce distinctive and recognizable sociocultural fingerprints [START_REF] Butzer | Accelerated soil erosion: a problem of man-land relationships[END_REF]1982;[START_REF] David | Handbook of Landscape Archaeology[END_REF]. Anthropogenic landforms have tended to increase in scale and complexity in parallel with the scale and complexity of the societies that produce them. Composed of individual land surface modifications, or "anthropogenic features", these are the products of socially and culturally directed efforts by individuals and social groups, increasingly assisted by animal labour, fossil-fuelled machinery and other non-human energy, to remove, transfer, introduce and reshape elements of the physical environment to achieve the goals of these individuals, social groups and entire societies. This social production of space generates a virtually endless variety of physical forms. We must therefore acknowledge at the outset the difficulties in dividing such myriad diversity of physical forms into neat categories according to their perceived function or meaning. Elements of material culture can, of course, be multifunctional, and polysemic, in ways that are arbitrary, unknowable and subject to variability over time. We argue, however, that there is practical and heuristic value in structuring the complexity of these physical forms into a generalized ontology of anthropogenic features, as in Figure 2: symbolic (e.g. graves and monuments), habitation (e.g. housing, villages, cities), transport and exchange (e.g. roads, canals), subsistence (e.g. plough furrows, irrigation networks), mining, refuse disposal and warfare (forts and battlements), among others.

Individual anthropogenic features are readily detectable on Earth's surface (or below) through observations made on their geometric forms, and possibly through a range of other physical or chemical attributes. Smaller scale societies, such as those of the first farmers, tend to produce a relatively narrow range of anthropogenic features. However, even small-scale societies produce a diversity of distinctive anthropogenic features on the landscape within the framework of their material culture. For example, a horticultural society produces building and settlement structures, hand-tilled fields, waste middens and graves, while the material culture of more complex societies is characterized by large-scale urbanism, ploughed fields, irrigation systems, mines and quarries, roads, monuments, cemeteries and many other anthropogenic features. These individual features are the fundamental elements of material culture at the landscape scale and, considered in aggregate, it is possible to identify the distinctive spatial patterning of a society elaborated across time and space on the surface of Earth: the sociocultural fingerprints of societies and cultures. The layering of these sociocultural fingerprints over landscapes over time, and their interactions with each other and the natural geomorphic processes that simultaneously shape them, combine to produce the landforms that cover most of Earth's terrestrial surface today.

Understanding the socioeconomic and sociocultural drivers of anthropogenic landscape evolution

To understand the socioeconomic and sociocultural forces that shape landscapes, it is first necessary to recognize that these operate at the scale of the societies engaging in them [START_REF] Ellis | Ecology in an anthropogenic biosphere[END_REF]. Human societies have long shaped terrain at local and regional scales. Now, human societies numbering in the billions are reshaping landforms globally through global-scale processes enabled by interconnected systems of economic, social, material and energy exchange, increasing levels of technological innovation and rapid socioeconomic development [START_REF] Fox | Engineering the Anthropocene: Scalable social networks and resilience building in human evolutionary timescales[END_REF][START_REF] Zalasiewicz | Scale and diversity of the physical technosphere: A geological perspective[END_REF]). Yet, even while the anthropogenic features and fingerprints generated by societies have tended to extend spatially across their areas of influence, their distributions are usually highly heterogeneous within and across these areas. Societal demands for food, minerals, settlements, economic exchange, symbolic communications and other needs are generally expressed unevenly across societal areas of influence to access the distribution of opportunities afforded by natural patterns of resource-use potential, such as fertile soils, level terrain, access to water and other societally perceived patterns defining their suitability for different uses, and also based on pre-existing social structures, such as settlements, transport infrastructures and areas of symbolic significance that define their value and accessibility for societal use (Butzer,1982b;[START_REF] Ellis | Ecology in an anthropogenic biosphere[END_REF].

The economic and social demands of global-scale societies are now met through processes that engage with social and environmental differences around the world at regional scales -where land, resources and labour are less expensive and more accessible. As a result, as socioeconomic demands and exchange processes have scaled up, some world regions are experiencing rapid increases in anthropogenic modification caused by deforestation and tillage to meet far-away food demands, road-building to interconnect global supply chains or dam construction to supply energy, while at the same time other regions are experiencing rapid decreases in such modifications and even complete abandonment by human populations [START_REF] Meyfroidt | Globalization of land use: distant drivers of land change and geographic displacement of land use[END_REF]. While uneven spatial patterns of anthropogenic landscape modification are just as common in small-scale societies, they tend to be produced by very different socioeconomic and sociocultural processes. In general, the forms, extents and distributions of anthropogenic landscape modifications must all be seen as variable across and within societies as a function of both pre-existing natural patterns, largely related to terrain and climate, and to preexisting sociocultural patterns, largely related to the cultural and technological capacities and patterns of social structures in space, and the varying interactions of different societies with these conditions (Butzer, 1982b;[START_REF] Ellis | Ecology in an anthropogenic biosphere[END_REF]. Anthropogenic landscape modifications are therefore a combination of cultural forms, technologies and natural environmental patterns, and can involve anthropogenic interventions that accelerate or delay natural geomorphological processes, producing hybrid anthropogenic/ natural features, or engineer entirely distinct anthropogenic features with purely cultural functions. For this reason, anthropogenic landforms vary widely in form and function, in the degree to which they are distinct in their spatial patterning from natural landforms and in the degree to which they may be recognized as the product of a specific cultural milieu. Whereas natural mass flows generally move from high to low positions or from upstream to downstream under the influence of natural forces, and their capacity to move dissipates over distance, landforms engineered through direct human agency are shaped primarily by social and cultural imperatives that produce landforms distinctly different from natural physical processes. Anthropogenic landscape engineering often represents elaborate attempts to subvert natural processes in culturally specific ways -by damming floodplains and diverting sedimentladen floodwaters into walled field systems, for example -which can in turn feed back into natural systems and generate consequential changes within them. To understand human modifications of landscape evolution across multiple scales of time and space, a basic framework for describing and classifying anthropogenic landforms is needed, together with an understanding of the underlying generative principles that produce them, and the nature and degree of their ability to alter the functioning of landscapes.

The diversity of anthropogenic geomorphic features

In this work we use the following categories to establish a basic, working framework for the classification of anthropogenic features: (i) symbolic; (ii) habitation; (iii) transport/ exchange; (iv) subsistence; (v) mining; (vi) water infrastructure; (vii) waste disposal; (viii) warfare. These heuristic categories encompass signatures of social functions in space and time. Features identified within these categories cover different spatio-temporal extents, and are affected differently by time-varying processes. As a consequence, the anthropogenic features described within these categories exist across a spectrum of scales in space and time, and also reflect a huge range of societal scales and complexities, from hearth pits to highway networks. The landscapes within which these features are embedded are also a function of spatio-temporal scale, depending on the overall area encompassed by a society (its extent in space) and its historical development (extent in time). When viewed at larger spatial scales, combinations of these features represent fingerprints of societal functions, from agriculture and settlements to industrial development, transport infrastructure and other functions.

Even at the level of individual features, which range from small (<1 m) to large (>1 km) in size, it can also be possible to identify specific societies directly from their anthropogenic landforms and features (Figure 2).

Symbolic

The first symbolic features of human societies are likely burial sites [START_REF] Belmonte | On the orientation of early bronze age tombs in ancient Magan[END_REF]. Entombments in ancient times have included caves and underground burials with different designs relating to the wealth and status of the deceased [START_REF] Cuezva | Composition, uses, provenance and stability of rocks and ancient mortars in a Theban Tomb in Luxor (Egypt)[END_REF]. As societies evolve, so have burial practices, from ground and cave burials to more elaborate constructions [START_REF] Sidebotham | Religion and burial at the Ptolemaic-Roman Red Sea emporium of Berenike, Egypt[END_REF][START_REF] Tomczyk | Anthropological analysis of the osteological material from an ancient tomb (Early Bronze Age) from the middle Euphrates valley, Terqa (Syria)[END_REF]. In many cultural contexts these funerary structures represent massive investments in reconfiguring the natural landscape, and their sheer size makes them relatively resistant to natural weathering and degradation [START_REF] Guthrie | The catastrophic nature of humans[END_REF]. In some instances, for example with geoglyphs, it is clear that landscape-scale transformations of the natural environment have been undertaken in order to encode meaning in geometric patterns (Briones-M, 2006;[START_REF] Tapete | Prospection and monitoring of the archaeological heritage of Nasca, Peru, with envisat asar[END_REF][START_REF] Tapete | Contextualising archaeological models with geological, airborne and terrestrial LiDAR data: The Ice Age landscape in Farndon Fields, Nottinghamshire, UK[END_REF]. Geoglyphs can play a role in mortuary practices as well as aiding in the trapping of migratory animals, and serving as cleared areas for camps, houses and animal enclosures [START_REF] Kennedy | The 'Works of the Old Men' in Arabia: Remote sensing in interior Arabia[END_REF]. They are formed of durable materials such as soil, stones, clastic rocks, live trees, gravel and earthworks [START_REF] Sparavigna | Geoglyphs of Titicaca as an ancient example of graphic design[END_REF].

Prehistoric agricultural societies, especially in parts of Europe, also produced large stone structures, or megaliths, including large single standing stones, as part of buildings, as portal dolmens, rotundas and passage graves, as well as henges, all of which served diverse but essential societal functions [START_REF] Beck | Landscape archaeology, paganism, and the interpretation of megaliths[END_REF][START_REF] Fleming | Phenomenology and the megaliths of Wales: A dreaming too far?[END_REF][START_REF] Fleming | Megaliths and post-modernism: The case of Wales[END_REF][START_REF] Holtorf | The life-histories of megaliths in Mecklenburg-Vorpommern (Germany)[END_REF][START_REF] Midgley | Monuments and monumentality: The cosmological model of the world of megaliths[END_REF]. Historical and contemporary societies also produce a wide variety of symbolic landscape features in parks and gardens, including stylized berms incorporated into artworks, and many shaped to mimic stylized natural landforms, such as those of central park in New York City [START_REF] Portal | The artificial mountain: a new form of "Artialization" of Nature?[END_REF].

Habitation

Early human encampments relied on rock shelters formed by natural processes, such as caves [START_REF] Farrand | Archaeological sediments in rockshelters and caves[END_REF][START_REF] Judson | Rockshelter archaeology and geoarchaeology in the Bighorn Mountains, Wyoming[END_REF][START_REF] Simms | Tur Imdai Rockshelter: Archaeology of recent pastoralists in Jordan[END_REF], whose natural and anthropogenic deposits offer details on human activities, natural environments inside such caves and their dynamic interactions over time [START_REF] Courty | The microstratigraphic record of abrupt climate changes in cave sediments of the Western Mediterranean[END_REF][START_REF] Farrand | Archaeological sediments in rockshelters and caves[END_REF]. With the rise of sedentary societies, especially those sustained by agriculture, people began to build more permanent shelters and to concentrate these in ever larger settlements, from seasonal encampments, to villages, towns, cities and ultimately into interlinked complexes of urban and rural landscapes sustaining large-scale social formations, or states [START_REF] Goudie | Geomorphology in the Anthropocene[END_REF].

As settlements grew in scale, these came to include not only housing but also specialized buildings for governance, crafts production, temples and other cultural needs, water infrastructure, road networks and boundary walls or fortifications [START_REF] Beranek | Stable Unstable? Structural Consolidation of Ancient Buildings[END_REF][START_REF] Campbell | The past at the precipice[END_REF][START_REF] Van Der Spek | The making of the ancient Greek economy. Institutions, markets, and growth in the city-states[END_REF]. Many early cities prospered, dwindled and disappeared, such as the Mesopotamian city of Ur, in ruins by 450 BCE [START_REF] Azara | Neolithic village of the SyroMesopotamian city[END_REF][START_REF] Launderville | The Book of Ezekiel and Mesopotamian City Laments[END_REF]. Other ancient cities have survived to the present, such as Jericho, one of the oldest inhabited cities in the world, well-known for its protective walls [START_REF] Issar | A tale of two cities in ancient Canaan: How the groundwater storage capacity of Arad and Jericho decided their history[END_REF]. As with Jericho, defensive enclosures are one of the most easily recognizable components of the archaeological record [START_REF] Boyce | Concrete connections? Articulation, homology and the political geography of boundary walls[END_REF][START_REF] Cassel | The Great Wall: A cultural history[END_REF][START_REF] Rojas | The Great Wall: A Cultural History[END_REF]. Other urban forms include the largescale urban complexes and hydraulic systems that evolved in densely forested landscapes in Asia and Amazonia [START_REF] Evans | Uncovering archaeological landscapes at Angkor using lidar[END_REF][START_REF] Liu | Earliest hydraulic enterprise in China, 5,100 years ago[END_REF][START_REF] Roberts | The deep human prehistory of global tropical forests and its relevance for modern conservation[END_REF]. The production of built structures, from walls to housing and those for other specialized purposes, induces a variety of geomorphic processes ranging from concentrated excavation to the intensive transport, deposition and restructuring of materials, to the creation of new artificial landforms. All of these intentional structuring processes tend to further enhance other geomorphic processes, including water accumulation, the deposition of waste materials in excavated areas, destabilizing of new landforms and underground structures, intensified erosion and other environmental consequences [START_REF] Courty | The microstratigraphic record of abrupt climate changes in cave sediments of the Western Mediterranean[END_REF][START_REF] Farrand | Archaeological sediments in rockshelters and caves[END_REF].

Transport/exchange networks

Urban development is also accompanied and facilitated by the development of transport networks composed of paths, unimproved and improved roads, railways and waterways connecting rural resources and people to distant markets and population centres [START_REF] Bell | Transportation Network Analysis[END_REF][START_REF] Kara | Designing a road network for hazardous materials transportation[END_REF][START_REF] Morriss | The Archaeology of Railways[END_REF][START_REF] Morriss | Roads: Archaeology and Architecture[END_REF][START_REF] Ruiz | Modern road archaeology: Identification and classification proposal[END_REF][START_REF] Snead | Landscapes of Movement: Trails, Paths, and Roads in Anthropological Perspective[END_REF]. Roads are ubiquitous features of landscapes and different shapes of road network represent the different evolution of civilization at different times [START_REF] Strano | Elementary processes governing the evolution of road networks[END_REF]. Road networks can reflect the central or decentralized organization of countries, and provide important pathways for mobility, migration and demographic change. They induce the rural to urban migrations as well as the massive emigration. In addition, since the Industrial Revolution, railroads have been an important form of transportation [START_REF] Li | Geography of railroads[END_REF][START_REF] Morriss | The Archaeology of Railways[END_REF], shaping not only cities and economic growth [START_REF] Hanedar | Transportation Infrastructure and Economic Growth in a Dissolving Country: (Ir)relevance of Railroads in the Ottoman Empire[END_REF][START_REF] Nerlove | Railroads and American economic growth[END_REF], but also landscape processes [START_REF] Bell | Transportation Network Analysis[END_REF]Blanton andMarcus, 2009, 2013;[START_REF] Kumar | Connectivity structure of the Kosi megafan and role of rail-road transport network[END_REF][START_REF] Martinović | Rainfall thresholds as a landslide indicator for engineered slopes on the Irish Rail network[END_REF]).

Railways, for example, can induce selective disclosure of the countryside [START_REF] Antrop | Landscape change and the urbanization process in Europe[END_REF]. Villages that received a station in some cases (but not always) developed rapidly into urban-like centres and their surrounding landscape changed accordingly. Developed road networks could also affect new urban development in tourist resort areas that once were remote rural regions with limited access [START_REF] Petrov | Urban land use scenarios for a tourist region in Europe: Applying the MOLAND model to Algarve, Portugal[END_REF]. The development of both networks (road and rail) is also accompanied by the use or even reshaping of the geomorphologic and topographic setting to create new infrastructure, tunnelling and bridges [START_REF] Booth | Tracks Through Time: The Archaeology of the Channel Tunnel Rail Link[END_REF][START_REF] Buchanan | The Baimoral Bridge of I[END_REF][START_REF] Day | Telford's Aberdeenshire bridges[END_REF][START_REF] Pratesi | Mapping interactions between geology, subsurface resource exploitation and urban development in transforming cities using InSAR Persistent Scatterers: Two decades of change in Florence, Italy[END_REF][START_REF] Watson | London Bridge: 2000 Years of a River Crossing[END_REF]. More recently, the development of underground tunnels for transport has created extensive subterranean networks in many large cities [START_REF] Zalasiewicz | Human bioturbation, and the subterranean landscape of the Anthropocene[END_REF].

Subsistence

Together with deposits of stone tools, hearths and other evidence of controlled fire for cooking, warmth and protection from predators are likely the earliest evidence of human transformation of geophysical environments [START_REF] Roebroeks | On the earliest evidence for habitual use of fire in Europe[END_REF][START_REF] Smith | Niche construction and the behavioral context of plant and animal domestication[END_REF][START_REF] Wrangham | Catching Fire: How Cooking made us Human[END_REF]. The earliest intentionally built fires were little more than controlled burns of woody and other flammable organic materials, but these evolved into hearths constructed of stones and earth, and ultimately into ovens, kilns and other larger scale fire containing structures. A typical hearth pit of the past formed a bowlshaped soil discoloration less than 1 m in diameter and less than 0.5 m deep, with evidence of soil or rock exposure to high temperatures (Wandsnider,1997), with differences in hearth-pit size and shape indicating different functions [START_REF] Crombé | Mesolithic hearth-pits: Fact or fantasy? A reassessment based on the evidence from the sites of Doel and Verrebroek (Belgium)[END_REF][START_REF] Pearson | The Archaeology of Death and Burial[END_REF]. Human engineering of environments for food production begins in the late Pleistocene with hunter-gatherer modification of landscapes to concentrate and trap game and the use of fire to clear and enhance vegetation growth, followed by the rise of agriculture in the early Holocene, involving the digging of holes for planting, soil tillage and the construction of livestock pens and fencing, activities continuing to the present day [START_REF] Ellis | Ecology in an anthropogenic biosphere[END_REF][START_REF] Ellis | Used planet: A global history[END_REF][START_REF] Smith | Modifying landscapes and mass kills: Human niche construction and communal ungulate harvests[END_REF][START_REF] Smith | The onset of the Anthropocene[END_REF]. Soil tillage leaves especially clear and widespread geomorphic signatures across landscapes in terms of anthropogenic soils and erosive deposits [START_REF] Certini | Anthropogenic soils are the golden spikes for the Anthropocene[END_REF][START_REF] Ellis | Anthropogenic transformation of the terrestrial biosphere[END_REF][START_REF] Tarolli | High-resolution morphologic characterization of conservation agriculture[END_REF]. The need to exploit steep lands for agriculture also introduced the construction of terraces [START_REF] Chase | Ancient Maya regional settlement and inter-site analysis: The 2013 West-Central Belize LiDAR survey[END_REF][START_REF] Tarolli | Terraced landscapes: From an old best practice to a potential hazard for soil degradation due to land abandonment[END_REF][START_REF] Vogel | Terrace farming in Yemen[END_REF]. Geomorphic features produced by livestock management include animal pens with soils altered by trampling and manure deposits, their surrounding fencing, sometimes constructed using rocks, earth and other durable materials, and the extension of fencing and animal paths across landscapes, often associated with water and shelter, including induced the deposition of stones and earth near fences, soil compaction and erosion from paths and disturbance and vegetation removal caused by overgrazing (Amy and [START_REF] Robertson | Relationships between livestock management and the ecological condition of riparian habitats along an Australian floodplain river[END_REF][START_REF] Mwendera | The effect of livestock grazing on surface runoff and soil erosion from sloping pasture lands in the Ethiopian highlands[END_REF][START_REF] Tarolli | Recognition of surface flow processes influenced by roads and trails in mountain areas using high-resolution topography[END_REF][START_REF] Wu | Grazing exclusion by fencing non-linearly restored the degraded alpine grasslands on the Tibetan Plateau[END_REF][START_REF] Yong-Zhong | Influences of continuous grazing and livestock exclusion on soil properties in a degraded sandy grassland, Inner Mongolia, northern China[END_REF][START_REF] Zhang | Vegetation and soil property response of short-time fencing in temperate desert of the Hexi Corridor, northwestern China[END_REF].

Mining

Although mining is as old as the manufacture of stone tools and leaves clear geomorphic signatures, it occupies a relatively small surface area worldwide [START_REF] Tarolli | Human topographic signatures and derived geomorphic processes across landscapes[END_REF]. Mining activity has been driven by a wide variety of objectives, including obtaining materials for making items such as tools, utensils, weapons, ornaments, decoration and currency [START_REF] Timberlake | New ideas on the exploitation of copper, tin, gold, and lead ores in Bronze Age Britain: The mining, smelting, and movement of metal[END_REF]. Mining of clay for bricks is also widespread and continues globally [START_REF] Aa | Manufacturing of bricks in the past, in the present and in the future: A state of the art review[END_REF]. Further mining drivers have been the need for structures, and machinery, and obtaining resources for energy, electronics, nuclear fission [START_REF] Hartman | Introductory Mining Engineering[END_REF][START_REF] Herrington | Road map to mineral supply[END_REF] and for low-carbon energy production [START_REF] Vidal | Metals for a lowcarbon society[END_REF]. As a consequence, various so-called "mining landscapes" have emerged all over the world since the 19th century. They are characterized by unique excavated, accumulated and planed landforms [START_REF] Dávid | Quarrying and other minerals[END_REF] that bear the signature of the material sought. Such signatures can be broadly separated into two classes: surface and underground, although combinations of the two may occur in time and space [START_REF] Mossa | Impacts of mining on geomorphic systems[END_REF]. The main characteristic is the persistence in time of the landform itself [START_REF] Chen | Open-pit mining geomorphic feature characterization[END_REF][START_REF] Hooke | Land transformation by humans: A review[END_REF][START_REF] Xiang | Open-pit mine geomorphic changes analysis using multitemporal UAV survey[END_REF] and of the related effects on the environment [START_REF] Kircher | Remote sensing observation of mining induced subsidence by means of differential SAR-interferometry[END_REF][START_REF] Mossa | Impacts of mining on geomorphic systems[END_REF][START_REF] Rivas | Geomorphic consequences of urban development and mining activities: An analysis of study areas in Spain and Argentina[END_REF][START_REF] Toy | Geomorphology and Reclamation of Disturbed Lands[END_REF].

Water infrastructure

Although several forces beyond water management combine to shape societies, the availability of water strongly influenced the trajectory of past societies [START_REF] Scarborough | The hydraulic lift of early states societies[END_REF]. As humans began to settle as farmers during the Neolithic, water wells and water infrastructures began to rise [START_REF] Angelakis | Evolution of Water Supply throughout the Millennia[END_REF][START_REF] Kollyropoulos | Urban planning and water management in Ancient Aetolian Makyneia, Western Greece[END_REF][START_REF] Tegel | Early Neolithic water wells reveal the world's oldest wood architecture[END_REF]. These features leave a distinctive topographic signature that can still be identified on the landscape today, thousands of years later [START_REF] Yevjevich | Water and civilization[END_REF]. An example of this would be Qanat, which are gently sloping underground channels designed to transport water from an aquifer or water well to the surface for irrigation and drinking [START_REF] Wessels | Qanats and Water Cooperation for a Sustainable Future[END_REF], originating in the first century and distributed mainly in the Iranian plateau and east of Xinjiang Province in China [START_REF] Goes | Karez (qanat) irrigation in the Helmand River Basin, Afghanistan: A vanishing indigenous legacy[END_REF][START_REF] Harandi | An appraisal of the qualifying role of hydraulic heritage systems: A case study of Qanats in central Iran[END_REF][START_REF] Luo | Automated extraction of the archaeological tops of qanat shafts from VHR imagery in google earth[END_REF]. Another example is the famous hydraulic infrastructure of Pont du Gard in southern France [START_REF] Dumas | The Fight at Pont du Gard[END_REF][START_REF] Vrancic | Pont Du Gard Pearl of the architectural heritage[END_REF]. Ditches provide further water infrastructure for reclamation purposes, irrigation and drainage alongside roadways or fields [START_REF] Terry | Drainage of excess water-Why and how[END_REF]. As well, canals provide water conveyance, navigation and water storage [START_REF] Swamee | General principles of canal design[END_REF]. Along water infrastructures, especially in floodplains, humans built embankments, levees and scarps. These infrastructures not only offer protection from floods, but they also change the flood frequency and create disconnectivity between the river landscape and its floodplain [START_REF] Chin | Urbanization and river channels[END_REF][START_REF] Gregory | The human role in changing river channels[END_REF][START_REF] Overeem | Impacts of humans on river fluxes and morphology[END_REF][START_REF] Thoms | Floodplain-river ecosystems: Fragmentation and water resources development[END_REF].

Another example of water control measures is provided by dams and reservoirs, which have increased dramatically in number and scale globally since the 1950s [START_REF] Chao | Anthropogenic impact on global geodynamics due to reservoir water impoundment[END_REF], to the point that water impounded in artificial reservoirs since the 1950s is by far the most significant anthropogenic hydrological change in terms of water volume [START_REF] Vörösmarty | Anthropogenic sediment retention: Major global impact from registered river impoundments[END_REF][START_REF] Vörösmarty | Human transforming the Global Water System[END_REF].These structures are built for irrigation purposes, water for human consumption, agricultural use, power generation, land drainage and reclamation, flood mitigation and recreational use [START_REF] Castelletti | Water reservoir control under economic, social and environmental constraints[END_REF]FAO, 2001;[START_REF] Meentemeyer | Effects of dam operation and land use on stream channel morphology and riparian vegetation[END_REF][START_REF] Hall | Temporal and spatial displacement: Evidence from a high-use reservoir and alternate sites[END_REF][START_REF] Le | The combined impact on the flooding in Vietnam's Mekong River delta of local man-made structures, sea level rise, and dams upstream in the river catchment[END_REF]. These functions are, however, accompanied by environmental changes, including subsequent impacts on lowland rivers and coastal systems, climate-changing greenhouse gases emissions, changes in the temperature regime, sedimentation, water pollution and destruction of ecosystems due to the reservoir effect on downstream environmental flows and sediment supply [START_REF] Dević | Environmental impacts of reservoirs[END_REF]. Artificial wetlands have also become ubiquitous in recent decades, and are a distinctive form of water management system created for the purpose of treating municipal or industrial wastewater, greywater or stormwater, to act as a biofilter and remove pollutants from the water and for land reclamation after mining, refineries or other ecological disturbances [START_REF] Elzein | Constructed wetlands as a sustainable wastewater treatment method in communities[END_REF][START_REF] Vymazal | The use of HF Constructed Wetlands in the World[END_REF][START_REF] Zhang | Constructed wetlands in China[END_REF]. Some of the most dramatic anthropogenic transformations of Earth's surface occur at the interface between terrestrial and aquatic environments, which include massive and elaborate mechanisms for displacing and managing water. Recent advances in engineering technology have allowed for extensive land reclamation and the creation of artificial islands to provide new spaces for development and to achieve political and strategic objectives [START_REF] Goudie | Geomorphology in the Anthropocene[END_REF][START_REF] Martín-Antón | Review of coastal land reclamation situation in the world[END_REF].

Refuse disposal

Middens are among the first and most prominent examples of physical remnants of resource exploitation activities in the archaeological record, with potential consequences for a range of related physical and chemical characteristics, for example increased soil alkalinity, and in particular increases in levels of nitrogen, calcium, potassium and manganese [START_REF] Cook-Patton | Ancient experiments: Forest biodiversity and soil nutrients enhanced by Native American middens[END_REF]. Middens offer an important archive of information about human dispersal and group diversification because they can be created either at the household level or the community level [START_REF] Trebsche | Does form follow function? Towards a methodical interpretation of archaeological building features[END_REF]. They preserve records that are particularly valuable for the development of interdisciplinary approaches in investigating human-environment interaction, social relations and the role of resource exploitation in the developmental trajectory of human groups [START_REF] Álvarez | Shell middens as archives of past environments, human dispersal and specialized resource management[END_REF][START_REF] Rick | From pleistocene mariners to complex huntergatherers: The archaeology of the california channel islands[END_REF]. They are also suitable for radiocarbon dating [START_REF] Brady | Contemporary indigenous relationships to archaeological features: Agency, affect, and the social significance of rock art[END_REF]. Another widespread remnant of past resource exploitation survives in the form of tells, artificial features (mounds) formed from the accumulation of refuse over millennia of settlement activities [START_REF] Portal | The artificial mountain: a new form of "Artialization" of Nature?[END_REF]. Their size and shape carry the fingerprint of diverse cultures and, in most cases, they are representative of the earliest settlement systems, beginning in the Neolithic period [START_REF] Menze | Detection of ancient settlement mounds[END_REF]. In modern times, middens and tells evolved as landfills used for waste management and processing waste material in the most costefficient way [START_REF] Stirling | The modern midden: Visualising waste through information design[END_REF]. The physical structure of landfills embodies diverse input characteristics, such as aspects of terrain, existing land use, aesthetic value, government regulations and public opinion about the sites themselves [START_REF] Sharma | Introduction to Process Geomorphology[END_REF].

Warfare

Landform features have also been created for warfare or deface. These features include not only artificial structures, such as fortifications [START_REF] Matos-Machado | Great War archaeo-geomorphology: Exploring the links between conflict-induced landforms and archaeological records in the battlefield of Verdun (Northeastern France)[END_REF][START_REF] Ilyés | Military activities: Warfare and defence[END_REF][START_REF] Moss | Forts, refuge rockes, and defensive sites: The antiquity of warfare along the North Pacific Coast of North America[END_REF], trenches [START_REF] Baer | Trench warfare, 19141918: The live and let live system[END_REF][START_REF] Houx | Trench warfare alternative trenching methods help with speed and efficiency[END_REF][START_REF] Power | Trench warfare under Grant and Lee: Field fortifications in the overland campaign[END_REF], improvised explosive device (IED) command wires [START_REF] Mcdonald | Use of ground-based LiDAR for detection of IED command wires on typical desert surfaces[END_REF], bunkers and missile silos, among others, but also existing underground terrain [START_REF] Eastler | Studies in Military Geography and Geology[END_REF] or rock defences [START_REF] Moss | Forts, refuge rockes, and defensive sites: The antiquity of warfare along the North Pacific Coast of North America[END_REF]). The most famous example of trench warfare is the Western Front World War I, which has become the classic example of stalemate, attrition and futility in modern conflict [START_REF] Baer | Trench warfare, 19141918: The live and let live system[END_REF]. However, this class of features also includes direct geomorphological evidence, such as bomb and mine craters [START_REF] Hupy | Introducing "bombturbation", a singular type of soil disturbance and mixing[END_REF][START_REF] Kiernan | Nature, severity and persistence of geomorphological damage caused by armed conflict[END_REF], uranium mining [START_REF] Blustain | Military Geosciences and Desert Warfare[END_REF] or landscape modification due to military structures [START_REF] Yatsko | Military development and geographic change on San Diego Bay[END_REF]. Clearly, conflicts leave a significant topographic signature on the landscapes, and they also result in long-term landscape modifications [START_REF] Bothe | Military activities and the protection of the environment[END_REF], with impacts on remoteness and naturalness, or on physical phenomena such as geodiversity (geology, landforms, soils and the natural processes that give rise to them) [START_REF] Kiernan | Nature, severity and persistence of geomorphological damage caused by armed conflict[END_REF].

The contribution of remote sensing

Remote sensing is increasingly used for the analysis of landform changes, both contemporary and historical. The concept of anthropogenic landscapes as sociocultural palimpsests composed of the overlapping sociocultural fingerprints of multiple societies provides a theoretical framework through which this growing body of remotely sensed data can be used to detect and interpret anthropogenic geomorphic features, landforms and landscapes. The necessary first stage of this interpretation is the identification and labelling of these features. In the last decade, a range of new remote sensing techniques has led to a dramatic increase in terrain information, providing new opportunities for a better understanding of Earth surface processes based on geomorphic signatures [START_REF] Tarolli | High-resolution topography for understanding Earth surface processes: Opportunities and challenges[END_REF].

These techniques have spurred renewed interest in the role of social-ecological systems in shaping Earth's surface [START_REF] Johnson | An observational and theoretical framework for interpreting the landscape palimpsest through airborne LiDAR[END_REF], ranging from studies of "archaeological topography" among social sciences [START_REF] Canuto | Ancient lowland Maya complexity as revealed by airborne laser scanning of northern Guatemala[END_REF][START_REF] Evans | Uncovering archaeological landscapes at Angkor using lidar[END_REF][START_REF] Opitz | Interpreting Archaeological Topography: 3D Data, Visualization and Observation[END_REF] to the study of "geomorphometry" among geoscientists [START_REF] Pike | Geomorphometry Diversity in quantitative surface analysis[END_REF]Sofia et al., 2016b). Technologies such as LiDAR (see [START_REF] Tarolli | High-resolution topography for understanding Earth surface processes: Opportunities and challenges[END_REF], for a review), satellite [START_REF] Purinton | Validation of digital elevation models (DEMs) and comparison of geomorphic metrics on the southern Central Andean Plateau[END_REF] and structure from motion -SfM -(see [START_REF] Eltner | Image-based surface reconstruction in geomorphometrymerits, limits and developments of a promising tool for geoscientists[END_REF][START_REF] Fonstad | Topographic structure from motion: a new development in photogrammetric measurement[END_REF][START_REF] James | Straightforward reconstruction of 3D surfaces and topography with a camera: Accuracy and geoscience application[END_REF], for reviews) have opened avenues for the analysis of anthropogenic signatures and processes [START_REF] Tarolli | High-resolution topography for understanding Earth surface processes: Opportunities and challenges[END_REF]. In this context, one of the actual challenges is the ability to model the anthropogenic morphologies, quantify them and analyse the links between anthropogenic elements and geomorphic processes. In the following sections, a few examples are provided on how remote sensing data can be used to extract and analyse anthropogenic features and quantify anthropogenic changes on the surface.

Extraction from imagery

Despite the limitation due to shadowing, angle of incidence or lack of topographic information under vegetation cover [START_REF] Mostafa | Shadow identification in high resolution satellite images in the presence of water regions[END_REF][START_REF] Quartulli | A review of EO image information mining[END_REF][START_REF] Sowmya | Modelling and representation issues in automated feature extraction from aerial and satellite images[END_REF], archaeologists have made use of radar and satellite images to reveal differences in texture, roughness, moisture content, topography and geometry of features and surfaces related to human activities, for example [START_REF] Evans | A comprehensive archaeological map of the world's largest preindustrial settlement complex at Angkor, Cambodia[END_REF][START_REF] Fowler | Satellite remote sensing and archaeology: A comparative study of satellite imagery of the environs of Figsbury Ring[END_REF][START_REF] Holcomb | Imaging radar and archaeological survey: An example from the Gobi Desert of Southern Mongolia[END_REF][START_REF] Holcomb | Imaging radar in archaeological investigations: An image processing perspective[END_REF][START_REF] Moore | Spaceborne and airborne radar at Angkor: Introducing new technology to the ancient site[END_REF][START_REF] Ricketson | An archeological reconnaissance by air in Central America[END_REF]. More recently, images from satellites have been used not only in relation to anthropogenic features in the context of urban studies (see [START_REF] Ghanea | Building extraction from high-resolution satellite images in urban areas: recent methods and strategies against significant challenges[END_REF], for a review), for cadastral boundary extraction [START_REF] Crommelinck | Review of automatic feature extraction from high-resolution optical sensor data for UAVbased cadastral mapping[END_REF][START_REF] Wassie | A procedure for semi-automated cadastral boundary feature extraction from high-resolution satellite imagery[END_REF] and oil spill detection [START_REF] Brekke | Oil spill detection by satellite remote sensing[END_REF], but also to identify target features in ongoing and posthumanitarian crisis scenarios [START_REF] Witharana | Who does what where? Advanced earth observation for humanitarian crisis management[END_REF][START_REF] Witharana | Evaluating remote sensing image fusion algorithms for use in humanitarian crisis management[END_REF]. In analyses of this type, image analysis techniques, such as wavelets and fusion algorithms, or texture analyses, can enhance and localize patterns related to human activities, and they can be used to extract features of interest, such as not only buildings, but also shelters and war/flood/earthquake damaged structures. To illustrate this point we show in Figure 3 a Pleiades satellite image. The study area is spatially stratified in environmentally similar land units (Figure 3(d)) using image analysis techniques (Figures 3(b) and (c)) and, thus, it is possible to identify those areas that are most likely to present anthropogenic landscapes (Figure 3(e)). Feature extraction from satellite images is, however, limited by shadows [START_REF] Mostafa | Shadow identification in high resolution satellite images in the presence of water regions[END_REF] and other technical issues, such as angle of incidence [START_REF] Quartulli | A review of EO image information mining[END_REF][START_REF] Sowmya | Modelling and representation issues in automated feature extraction from aerial and satellite images[END_REF]. Satellite images, furthermore, cannot be used to extract ground features under vegetation cover. [START_REF] Haralick | 18 Image texture survey[END_REF]; (d) iterative optimization clustering procedure implemented by the commercial software ArcGis® [START_REF] Ball | ISODATA, a Novel Method of Data Analysis and Pattern Classification[END_REF][START_REF] Richards | Remote Sensing Digital Image Analysis: An Introduction[END_REF]; (e) extracted buildings.

Extraction from three-dimensional surfaces

A further step in feature extraction is allowed by the availability of three-dimensional (3D) models (Digital Terrain Models -DEMs). When DEMs are available, the most straightforward approach to anthropogenic feature analysis is visualization, namely the use of hillshade or shaded-relief maps (Figure 4(a)), for example [START_REF] Bennett | A comparison of visualization techniques for models created from airborne laser scanned data[END_REF][START_REF] Chase | Ancient Maya regional settlement and inter-site analysis: The 2013 West-Central Belize LiDAR survey[END_REF][START_REF] Deforce | Selective woodland exploitation charcoal production. A detailed analysis of charcoal kiln remains (ca. 1300-1900 AD) from Zoersel (northern Belgium)[END_REF][START_REF] Doneus | Archaeological prospection of forested areas using fullwaveform airborne laser scanning[END_REF][START_REF] Golden | Environmental lidar data for archaeology: Mesoamerican applications and reanalyzing implications[END_REF][START_REF] Harmon | LiDAR for archaeological landscape analysis: A case study of two eighteenth-century Maryland plantation sites[END_REF]Johnson andOuimet, 2016, 2018;[START_REF] Menze | Detection of ancient settlement mounds[END_REF]Risbøl et al., 2013;[START_REF] Tapete | Contextualising archaeological models with geological, airborne and terrestrial LiDAR data: The Ice Age landscape in Farndon Fields, Nottinghamshire, UK[END_REF]. This approach simulates lights and shadows to enhance the presence of features captured by the input dataset. Slightly more advanced techniques, based on compound approaches, have been also developed, such as the sky view factor (Figure 4(b)) [START_REF] Bennett | A comparison of visualization techniques for models created from airborne laser scanned data[END_REF][START_REF] Devereux | Visualisation of LiDAR terrain models for archaeological feature detection[END_REF][START_REF] Kennelly | Terrain maps displaying hill-shading with curvature[END_REF][START_REF] Štular | Visualization of lidar-derived relief models for detection of archaeological features[END_REF] or advanced analysis of hillshades (O 'Neal, 2012). The advanced use of topographic parameters directly derived from the DEMs allows not only for the visualization, but also for the classification of anthropogenic features. The most direct and straightforward approach is offered by the so-called "detrending" techniques. Data are filtered using "low pass" filters, resulting in a smoothed surface to subtract from a LiDAR DEM (Figure 4(c)), for example [START_REF] Cazorzi | Drainage network detection and assessment of network storage capacity in agrarian landscape[END_REF][START_REF] Hesse | LiDAR-derived Local Relief Models A new tool for archaeological prospection[END_REF][START_REF] Howey | Detecting precontact anthropogenic microtopographic features in a forested landscape with lidar: a case study from the upper great lakes region, AD 1000-1600[END_REF][START_REF] Luscombe | What does airborne LiDAR really measure in upland ecosystems?[END_REF][START_REF] Schindling | LiDAR as a tool for archaeological research: A case study[END_REF]Sofia et al., 2014c). As the z values in the detrended data represent the height difference from a smoothed surface, peak values in either the positive or negative domain (depending on the approach) highlight the microtopographic element in the landscape, such as drainage features or pits, or walls. Further useful topographic parameters can be used, such as slope (Figure 4(d)), (e.g. [START_REF] Mccoy | Airborne lidar survey of irrigated agricultural landscapes: an application of the slope contrast method[END_REF][START_REF] Riley | Lidar Surveyor: A Tool for Automated Archaeological Feature Extraction from Light Detection and Ranging (LiDAR) Elevation Data[END_REF], slope and also exposure under a water surface [START_REF] Cappucci | Detection of natural and anthropic features on small Islands[END_REF] and curvature (Figure 4(e)), [START_REF] Drăguţ | Automated classification of landform elements using object-based image analysis[END_REF]Sofia et al., 2014a;[START_REF] Tarolli | Terraced landscapes: From an old best practice to a potential hazard for soil degradation due to land abandonment[END_REF]. Recent literature has highlighted how image processing local filters can also be applied to a DEM to detect high-frequency variations (e.g. Laplacian -Figure 4(f), Sobel's filters, SLLAC -Slope Local Length of Correlation) (Sofia et al., 2014b(Sofia et al., , 2016;;[START_REF] Stal | Kemmelberg (Belgium) case study: Comparison of DTM analysis methods for the detection of relicts from the First World War[END_REF][START_REF] Štular | Visualization of lidar-derived relief models for detection of archaeological features[END_REF]. These enhancing techniques can be the basis to segment and detect anthropogenic patterns and features using GEOBIA (GEOgraphic-Object-Based Image Analysis) (see [START_REF] Blaschke | Geographic object-based image analysis Towards a new paradigm[END_REF][START_REF] Cerrillo-Cuenca | An approach to the automatic surveying of prehistoric barrows through LiDAR[END_REF][START_REF] Diaz-Varela | Automatic identification of agricultural terraces through object-oriented analysis of very high resolution fDSMsg and multispectral imagery obtained from an unmanned aerial vehicle[END_REF][START_REF] Eckert | Identification and classification of structural soil conservation measures based on very high resolution stereo satellite data[END_REF][START_REF] Hay | Geographic Object-Based Image Analysis (GEOBIA): A new name for a new discipline[END_REF] or automatic thresholding (e.g. Figure 5).

Quantitative assessment of features

Extractions carried out with thresholding or object-oriented approaches, although able to detect the two-dimensional (2D) location of anthropogenic elements, are not able to quantify whether or not they are continuous features in the landscape. Nevertheless, they can offer the basis for further evaluations of lengths, densities and volumes, for example (Sofia et al., 2014c;[START_REF] Sofia | Hydrological response to 30 years of agricultural surface water management[END_REF][START_REF] Sofia | On the linkage between runoff generation, land drainage, soil properties, and temporal patterns of precipitation in agricultural floodplains[END_REF], or the extent of 2D features. In addition, high-resolution DEMs can offer the basis to measure the shape and sizes of anthropogenic elements directly in the digital realm [START_REF] Johnson | Physical properties and spatial controls of stone walls in the northeastern USA: Implications for Anthropocene studies of 17th to early 20th century agriculture[END_REF]Sofia et al., 2016a). A further step in anthropogenic features characterization is offered by change detection techniques or time-series data analysis, which has gained significant attention due to its capability of providing volumetric and extent measures in time (see Qin et al., 2016, for a review). These techniques rely on the availability of multitemporal datasets, real or simulated, to be used to compare anthropogenic features in time [START_REF] Haas | Quantification and analysis of geomorphic processes on a recultivated iron ore mine on the Italian island of Elba using longterm ground-based lidar and photogrammetric SfM data by a UAV[END_REF]Prosdocimi et al., 2015;[START_REF] Wróżyński | Ground volume assessment using 'Structure from Motion' photogrammetry with a smartphone and a compact camera[END_REF][START_REF] Xiang | Open-pit mine geomorphic changes analysis using multitemporal UAV survey[END_REF][START_REF] Yucel | Areal change detection and 3D modeling of mine lakes using highresolution unmanned aerial vehicle images[END_REF]. Figure 6 shows an example of geomorphic change detection evaluated considering the [START_REF] Wheaton | Accounting for uncertainty in DEMs from repeat topographic surveys: Improved sediment budgets[END_REF] approach. For this area, multitemporal orthophotos (Figures 6(a) and(d)) andLiDAR DEMs (Figures 6(b) and(e)) are freely available (Institut Cartografic De Catalunya (ICC), 2005, 2008) for the years 2005 and 2008. From these maps, it is possible to compute a volumetric difference (Figure 6(c)), taking into account the errors that might be present in the DEMs themselves (see [START_REF] Lane | Estimation of erosion and deposition volumes in a large, gravel-bed, braided river using synoptic remote sensing[END_REF], for specification on the method).

Limits and merits

Improvements in spectral, spatial and temporal resolution are revealing more and more rich and detailed information to decipher landscape palimpsests. The synoptic view offered by compound analyses integrating satellite, airborne and photogrammetry enable integrated landscape investigations across scales in terms of resolution and coverage, from small features to entire regions, and comparisons across and within regions, and long time series allow monitoring and diachronic analysis of changes in landforms. Recent availability of wide-area, high-resolution LiDAR is revolutionizing these efforts, owing to its unique capability to penetrate vegetation canopies and identify earthwork features at high spatial resolutions even under dense vegetation cover.

Challenges remain for using these data to detect anthropogenic features and their distributions across landscapes and regions. A better understanding of the representation of anthropogenic features within the data itself will be critical, combined with improvements in processing techniques that make analyses of vast quantities of data more manageable. Moreover, each study presents its own challenges. For example, traces of ancient ruins and infrastructures might lie below relatively modern roads, buildings and agricultural fields, or ancient structures might be made of the same material that underlies a whole study area. A further impediment to reliable feature identification is that long-term exposure to natural environmental processes, such as erosion and sediment deposition, can make anthropogenic features extremely difficult to distinguish from natural ones [START_REF] Liu | Earliest hydraulic enterprise in China, 5,100 years ago[END_REF]. A clear example of this is the effect of natural weathering processes on landfills or tells: ancient mounds nowadays might resemble natural hillslopes, and modern landfills will, over time, tend to smooth out to the same level as the surrounding land surface. Developments in computer science and statistics offer a wide range of powerful tools to augment the detection and interpretation of anthropogenic features, and potentially the sociocultural fingerprints of entire societies across large regions. These tools include advanced systems for geographic information systems (GISs), 3D modelling, predictive modelling, visualization, simulations and machine learning (e.g. [START_REF] Guyot | Detecting Neolithic burial mounds from LiDAR-derived elevation data using a multi-scale approach and machine learning techniques[END_REF]. Ironically, however, there remains no standard ontological framework within which to classify and understand anthropogenic landscapes and the features within them, despite their coverage of the vast majority of Earth's terrestrial surface [START_REF] Ellis | Used planet: A global history[END_REF]. By developing standardized frameworks for feature and fingerprint detection and interpretation, and ultimately by automating these, rapidly expanding Earth coverage by high-resolution 3D remote sensing can be utilized to examine Earth's global geomorphic transformation by human societies, together with a wide range of other useful societal applications [START_REF] Tarolli | Mapping the topographic fingerprints of humanity across Earth[END_REF].

Decoding palimpsest: From features to fingerprints

Few existing landforms are formed solely through natural or anthropogenic geomorphic processes operating within a single discrete time period. By and large, landforms tend to incorporate multiple interwoven and entangled layers of materials, both natural and anthropogenic, generated by different processes at different times, written and rewritten repeatedly by various combinations of natural and anthropogenic processes: landscapes are palimpsests [START_REF] Johnson | An observational and theoretical framework for interpreting the landscape palimpsest through airborne LiDAR[END_REF]. In any given region, therefore, complex overlapping topographic signatures can be observed. Some landform features might be very young because they are currently being shaped, but they may also bear the signature of historical modifications under specific social conditions or natural geomorphic processes that are no longer present in that region. Some other features may be entirely "relictual" because they were formed at some point in the past when social conditions, processes or environments were substantially different or operated at a different magnitude to those of the present time.

While remote sensing together with algorithmic methods enable the detection and identification of anthropogenic and other features, researchers are rarely able to observe or interpret these features across the scales of time or space in which the societies that formed them operated, although reconstructions of these long-term changes have long been a major focus of archaeological research (e.g. Butzer, 1982b;[START_REF] Dincauze | Environmental Archaeology: Principles and Practice[END_REF]. This remains the central challenge of anthropogenic geomorphology: to interpret anthropogenic features as diagnostic fingerprints of the societies and social processes that formed them, both locally and across the entirety of the regions where these societies were located. To meet this challenge requires an integrated social-geophysical approach combining the theories, frameworks and methods of geomorphology, archaeology and ecology.

General principles of sociocultural landscape formation

The first principle of anthropogenic geomorphology is that the sociocultural processes that form anthropogenic landforms are fundamentally different to natural processes like erosion or deposition.

Even though natural and anthropogenic geomorphic features may share real similarities in form and even function (Figure 7), the processes forming them are fundamentally different. Unlike the forces of gravity, hydrology and geophysics, which have not changed since the formation of this planet, the forces of landscape change generated by human societies can and have changed dramatically over time, together with societies themselves (Figures 1 and8).

The first step towards a process-based understanding of anthropogenic geomorphology is therefore the development of a timeline of known sociocultural changes across the landscape of interest, with the aim of understanding the historical layering of anthropogenic features, together with a timeline of major natural environmental changes and events, including major changes in precipitation, floods, tectonic and volcanic activity that have interacted with anthropogenic processes in forming the landscape under observation. This basic timeline should include a catalogue of the types of anthropogenic features created by different societies, including any geometric, symbolic or other cultural identifiers that can assist in reconstructing the layers of anthropogenic features produced across landscapes during specific periods of time. By combining social-geomorphologic timelines with detailed spatial data on landform structure, the spatial patterning of anthropogenic features and landforms may be understood in terms of the sociocultural and natural processes that have formed them. While the full range of sociocultural patterns, processes and dynamics observed across human societies (Figure 1) is far larger than those occurring within any particular landscape, Figure 1 illustrates that anthropogenic geomorphic practices can be completely different in different societies, and that larger, more complex societies tend to engage in a larger number of different types of anthropogenic geomorphic practices and that the size of geomorphic features is also associated with societal scales (larger scale societies are generally capable of producing larger scale features). As the features of earlier societies can be added to by societies that come later, the total number of different types of anthropogenic features should be expected generally to increase over time, although the removal, destruction and overwriting of earlier features by later societies can erase or reduce the accumulation of landform complexity, as can erosion and other natural processes.

A second principle of anthropogenic features and landforms is that their constituent materials may differ dramatically from those found naturally within a specific landscape or region [START_REF] Zalasiewicz | Scale and diversity of the physical technosphere: A geological perspective[END_REF]. The presence and composition of these materials, from stone, wood and other materials distinct from local materials and transported from other areas, to bricks, concrete, steel and other materials produced exclusively by human societies, and the presence and spatial organization of anthropogenic materials can be diagnostic of anthropogenic geomorphology -and detectable using remote sensing. The use of anthropogenic materials also enables the construction of anthropogenic features without natural analogues, from buildings to highway overpasses. As with feature types and sizes, the number of different types of materials utilized in feature construction also tends to increase with societal scale, with larger scale societies generally deploying a greater number of novel materials across anthropogenic landscapes. A third principle of anthropogenic geomorphology is that within the regions influenced by a given society, the sociocultural functions that create anthropogenic features are not homogeneous, but rather differ across space in relation to both social and natural patterns. For example, within agrarian societies, there are often distinct clusters of connected by paths and roads, with agricultural fields and irrigation systems in the flatter lands in between, with less used areas on hillslopes. Larger scale urban societies show similar social patterns, but these may operate at much larger scales, and even globally at the present time. These patterns are aligned with the broader model of human sociocultural niche construction [START_REF] Ellis | Ecology in an anthropogenic biosphere[END_REF], as modified and illustrated by the state equation: Anthropogenic landforms = f(biome, terrain, societies, centrality, time). This model describes the anthropogenic landforms produced in a given location in terms of its general biogeophysical conditions (biome, e.g. desert, savannah, rainforest), the specific terrain (terrain, e.g. floodplain, hillslope, mountain top), the societies that have operated at the location, the social position within the societies' operating spaces (social centrality, i.e. the travel distance from social centres, such as villages, towns and cities, the opposite of remoteness) and the amount of time over which the anthropogenic processes have operated. Based on this simple conceptual model, the types of features present within a specific location are contextualized both within the social space of the societies operating across a given site or region, with anthropogenic features produced by habitation expected to occur at high frequencies in areas of high social centrality, with transport features interconnecting these, while subsistence, mining, refuse, water infrastructure and other anthropogenic features are distributed in relation to suitable terrain and distance from social centres.

In smaller scale societies, these functions and features tend to be tightly clustered in space, sometimes with the exception of symbolic and mining features, while larger scale societies tend to distribute these functions and features more widely, even globally. By combining these general principles of sociocultural landscape formation in relation to underlying biogeophysical conditions, the spatial patterning of anthropogenic features and landforms can be understood as the sociocultural fingerprints of the societies that have constructed them.

From features to fingerprints

Although anthropogenic features can increasingly be detected through remote sensing and distinguished from natural features as a function of their shape and material composition, a separate process of anthropogenic landscape interpretation is needed to understand their sociocultural and functional identity and their relation to the sociocultural processes that formed them -the basis both for feature classification and labelling and for the interpretation of features across landscapes and regions to identify the sociocultural fingerprints of societies. Automated feature classification is now increasingly capable of identifying classes of relatively homogeneous 3D entities (Figure 3(d)), but without further understanding of their sociocultural functions, such as habitation, symbolic culture or water infrastructure, these classifications remain purely geometric, and feature shape can at times be an unreliable indicator of function. Nevertheless, there is growing technological capacity for defining feature templates describing the geometry of specific anthropogenic feature classes, thereby enabling automated feature function identification and labelling using template matching [START_REF] Schneider | A Templatematching approach combining morphometric variables for automated mapping of charcoal kiln sites[END_REF], object-oriented techniques [START_REF] Blaschke | Geographic object-based image analysis Towards a new paradigm[END_REF] and/or machine learning approaches [START_REF] Valentine | An introduction to learning algorithms and potential applications in geomorphometry and earth surface dynamics[END_REF]. There is great promise in using these and other methods, including supervised feature classification leveraging spectral and geometric signatures developed by archaeologists and physical geographers with knowledge of the social-geomorphic timeline of a given landscape and its associated anthropogenic features, to train automated procedures to identify specific functional forms of anthropogenic features, such as buildings (Figure 3(e)). Caution is necessary, however, as natural landforms can have similar shapes to anthropogenic features: for example, a hearth-pit, a bomb crater and a karstic sinkhole might all have very similar geometry.

The confusion of natural and anthropogenic patterns across landscapes can present similar challenges to the automated analysis of sociocultural fingerprints. A wide variety of natural spatial features have been shown to be statistically self-similar over many scales, suggesting that fractal patterns are a signature of natural geomorphic patterns [START_REF] Goodchild | The fractal nature of geographic phenomena[END_REF][START_REF] Rodriguez-Iturbe | Fractal River Basins: Chance and Self-Organization[END_REF][START_REF] Tarboton | The fractal nature of river networks[END_REF]. For example, road networks can assume dendritic forms very similar to those of river networks (Figure 7), and agricultural terraces can resemble river terraces.

Yet, built-up environments may also possess similar structures at several different scales [START_REF] Batty | The size, scale, and shape of cities[END_REF][START_REF] Batty | Fractal Cities: A Geometry of Form and Function[END_REF][START_REF] Frankhauser | The Dynamics of Complex Urban Systems[END_REF][START_REF] Thomas | The morphology of built-up landscapes in Wallonia (Belgium): A classification using fractal indices[END_REF]. Road networks, for example, are inherently fractal [START_REF] Liu | Relationships between fractal road and drainage networks in Wuling mountainous area: Another symmetric understanding of human-environment relations[END_REF]. Nevertheless, patterns of statistical self-similarity may yet prove capable of identifying differences between natural geomorphology and sociocultural fingerprints by developing rule-based systems for the classification of spatial-scale dependence of largescale geomorphic patterns [START_REF] Jiang | A fractal perspective on scale in geography[END_REF]. The automated detection of larger scale patterns by aggregate assessment of feature composition and configuration across space through deep learning algorithms offers a clear way forward, analogous to progress with automated fingerprint detection in forensics [START_REF] Schmidhuber | Deep learning in neural networks: An overview[END_REF].

A way forward

The future of anthropogenic geomorphology will depend on a level of integration between theory and methodology that goes far beyond what we have presented here. Nevertheless, the way forward is clear, requiring a focus on the broader sociocultural, spatial and temporal contexts of anthropogenic landscape formation, rather than the mere presence or absence of specific anthropogenic features.

Analysing the spatial structuring of features across landscapes in relation to the sociocultural and material systems that have shaped them can be essential to determine whether features have originated naturally, have anthropogenic origins or have emerged through the interplay of social and natural processes. One example of this broader focus on sociocultural fingerprints is the differential patterning of urban landscapes around the world (Figure 8). Centuriation (Figure 8 Other examples of sociocultural fingerprints include the spatial patterning of waste disposal sites from informal middens to the regionally planned systems of larger scale societies [START_REF] Sharma | Introduction to Process Geomorphology[END_REF], the integration of green spaces into cities, the development of "agro-urban landscapes" integrating traditional agrarian landscape patterns within contemporary urban/ industrial developments [START_REF] Cavallo | Mapping and assessing urban agriculture in Rome[END_REF][START_REF] Evans | Airborne laser scanning as a method for exploring long-term socio-ecological dynamics in Cambodia[END_REF][START_REF] Seto | Quantifying spatiotemporal patterns of urban land-use change in four cities of China with time series landscape metrics[END_REF] and the spread of road networks [START_REF] Corcoran | Analysing the growth of OpenStreetMap networks[END_REF][START_REF] Strano | Elementary processes governing the evolution of road networks[END_REF]. Even more detailed understanding of the functional roles of anthropogenic geomorphology can even enable the detection of specific cultivation practices. For example, different patterns of ditch networks (Figures 5(c) and (f)) support different cultivation practices (e.g. tobacco (Figure 5(a) and corn Figure 5(d)), and identifying these patterns requires a deeper understanding of the sociocultural practices of the societies that formed and/or operated them. Such an understanding, formed through careful reconstructions of the material cultures of societies across sites, is at the core of much archaeological research (Butzer, 1982b;[START_REF] David | Handbook of Landscape Archaeology[END_REF]. As the spatial and social scale of societies has increased, so have their capacities to reshape landforms locally, regionally and globally. Evidence already supports the hypothesis that anthropogenic transformations of land surface processes now move more of Earth's surface than any pre-existing natural process [START_REF] Wilkinson | The impact of humans on continental erosion and sedimentation[END_REF][START_REF] Zalasiewicz | Scale and diversity of the physical technosphere: A geological perspective[END_REF]). Yet, these broad estimates of anthropogenic global change demand to be assessed with the greater precision and spatial context made possible by highresolution reconstructions of anthropogenic geomorphic changes at local and regional scales. These measurement capabilities, for example the computation of volumetric changes caused by anthropogenic reshaping of landforms (e.g. Figure 6(c)), are only increasing as a result of advances in sensor systems, computational technology and large-scale data sharing, making the prospect of quantifying processes of anthropogenic geomorphic change globally over the long term a real possibility [START_REF] Tarolli | Mapping the topographic fingerprints of humanity across Earth[END_REF]. The prospect of global assessment of anthropogenic geomorphology is illustrated in Figure 9, examining a suite of sites around the world in which anthropogenic geomorphology has been mapped using satellite and LiDAR data available to the public as free opendata or as samples. Given that different uses of land are expected to shape different landforms differently (e.g. Sofia et al., 2014b), stratifying these observations in relation to global patterns of land use, such as the anthropogenic biomes (Figure 9), may offer a general sampling framework for the global mapping and quantification of anthropogenic geomorphic change.

Anthropogenic geomorphology forms just one of many layers of the evolving geomorphic palimpsests that now cover most of Earth's dynamic terrestrial surface. Through a systematic assessment of anthropogenic geomorphology around the world and across time periods, it may yet be possible to develop a more general framework, perhaps even a predictive theory, on the geomorphological niche of societies, uniting the analysis of distinct geomorphic features to assess the evolving sociocultural fingerprints of societal change.

Concluding remarks

Human societies, across millennia, have reshaped Earth's geomorphology, producing distinctive anthropogenic landforms that now cover the vast extent of Earth's surface. These anthropogenic patterns directly and indirectly alter Earth surface processes while reflecting the sociocultural conditions of the societies that produced them. As a result, both archaeological and contemporary assessments of Earth's surface morphology reveal a wealth of diverse anthropogenic geomorphic features that can serve as diagnostic signatures or "sociocultural fingerprints" of the societies that formed them, including their interaction and communication with other societies. This paper offers a general framework aimed at integrating geophysical and archaeological approaches to observe, identify and interpret anthropogenic geomorphic features, based on their societal structure and functioning. By introducing the concept of "sociocultural fingerprints", we connect the novel Earth system processes introduced by the emergence and evolution of human societies with their continuous shaping and reshaping of Earth's geomorphology from the deep past into the foreseeable future. Building on this concept, we underline the opportunity to recognize the geomorphic signatures of sociocultural fingerprints across Earth's land surface using high-resolution remote sensing approaches combined with an empirical and theoretical framework that integrates the natural and sociocultural forces that have and will shape the landscapes of the Anthropocene. By engaging these frameworks together, the long-term dynamics of anthropogenic landscapes can be more effectively investigated and understood, towards more sustainable management of the Earth system, including its hydrosphere and lithosphere, into the deep future.

Figure 1 .

 1 Figure 1. Conceptual diagram of long-term changes in sociocultural systems, cultural inheritances, societal scale, energy use and anthropogenic geomorphic features. Different societies combine different sets of anthropogenic geomorphic features, including both pre-existing and novel, to produce their sociocultural fingerprints across landscapes (this figure expands on

Figure 2 .

 2 Figure 2. Examples of anthropogenic geomorphic features, their sociocultural functions, and derived fingerprint on topography. From top to bottom: hearth-pit (Shahack-Gross et al., 2014); West Kennet Long Barrow in Avebury, Wiltshire (UK), one of the largest and most impressive Neolithic graves in Britain (3650 BC) (ph: © Skyscan Balloon Photography; LiDAR: Survey Open Data UK); The Long Man of Wilmington on South Downs in Sussex, UK (ph. Steve Slater, LiDAR: Survey Open Data UK); rock shelter (ph. Bernard Gagnon); Stonehenge (UK) (LiDAR: Survey Open Data UK); building in Lugo (Spain) (ph. Luis Miguel Bugallo Sánchez; LiDAR: © Centro Nacional de Información Geográfica); El Tolmo (Spain), archaeological site showing a continuous time record of ancient civilizations from 3500 yr BP onwards (ph. Laclac; LiDAR: © Centro Nacional de Información Geográfica); El Tolmo (Spain), archaeological site showing a continuous time record of ancient civilizations from 3500 yr BP onwards (ph. Laclac; LiDAR: © Centro Nacional de Información Geográfica); Roman wall of Lugo (Spain) (ph Xosema; ; LiDAR: © Centro Nacional de Información Geográfica); mountain road(ph. Chell Hill, LiDAR:

Figure 2 .

 2 Figure 2. (Continued). OpenTopography Facility); shell middens at Mound Key (Florida) (http://www.flpublicarchaeology.org/blog/crc/tag/soil-core/; LiDAR: NOAA National Oceanic Atmospheric Association website); cow trails (ph. Herzi Pinki, LiDAR: LiDAR Laserscanning-Geodaten Kanton Zürich, Amt für Raumentwicklung Geoinformation GIS-Produkte); rice terraces in the Philippines (University of the Philippines TCAGP); Bingham Canyon copper mine, UT, USA (ph. Spencer Musick; LiDAR: MNTOPO®); agricultural ditch in the Netherlands (ph. Tup Wanders, LiDAR: Dutch National Spatial Data Infrastructure -PDOK-); the Mittellandkanal, the longest artificial waterway in Germany (LiDAR: Geschaftsstelle des IMA GDI Nordrhein-Westfalen); riverbank in Italy (Google ©2017; LiDAR: Italian Ministry of Environment); Leech Lake Minnesota (LiDAR: MNTOPO®); constructed wetland in Northern Italy (Ph Adige Euganeo; LiDAR: Italian Ministry of Environment); Nagià Grom war trenches in northern Italy (ph. Kevin1971; LiDAR: Autonomous Province of Trento).

Figure 3 .

 3 Figure 3. Example of satellite image, derived texture parameters and classification: (a) Pleiades 0.5 m satellite image; (b) local range of values (max-min); (c) local standard deviation of values within a 11 x 11 neighbourhood[START_REF] Haralick | 18 Image texture survey[END_REF] (d)

Figure 4 .

 4 Figure 4. WWI trenches and terraces: (a) hillshade; (b) sky-view factor; (c) detrended Digital Terrain Model (DEM); (d) slope; (e) curvature; (f) Laplacian filtered DEM.

Figure 5 .

 5 Figure 5. Agricultural practices in northeastern Italy ((a) tobacco; (d) corn). Detrended Digital Terrain Model (REA, Cazorzi et al., 2013) (b), (e) and ditches derived automatically by applying a statistical threshold (standard deviation of Relative Elevation Attribute (REA)) (c), (f).

Figure 6 .

 6 Figure 6. Example of change of detection from LiDAR Digital Terrain Model (DEM). Ortophotos for the year 2005 (a) and 2008 (c), LiDAR DEM in 2005 (b) and 2008 (e) and derived change of detection in m (c).

Figure 7 .

 7 Figure 7. Example of similarity between anthropogenic and natural features: (a) local road network; (b) flowlines in Pennsylvania (USA).

Figure 8 .

 8 Figure 8. Different patterns (a), (d) highlight different cultural settings. Roman centuriation of an area near Padua (Italy (b)) and Valencia (Spain (c)), and modern residential areas in Milton Keynes (UK (e)) and Boulder (USA (f)).

Figure 9 .

 9 Figure 9. Local-scale percentage of anthropogenic geomorphology, as compared to anthropogenic biomes (Ellis and Ramankutty, 2008). Dataset credit: (a) Minnesota Geospatial Information Office (MnTOPO®); (b) Halifax Regional Municipality -Canada; (d) Autonomous Province of Trento (Provincia Autonoma di Trento, Italy); (e) Department of Environment, Food and Rural Affairs, UK; (f) Sturelsen for Dataforsyning og Effektivisering; (g) National Land Survey Finland; (h) Sample data by the Lantmäteriet (Sweden); (c), (i), (j), (k), (l) data from CNES© Distribution Airbus DS; (m) TERN© AusCover; (n) OpenTopography Facility with support from the National Science Foundation under NSF Award Numbers 0930731 & 0930643 FAPESP grant 2009/17675-5

  (a)) is typical of regions historically conquered by Romans (such as Italy (Figure 8(b) and Spain Figure 8(c)). In such cases, the city/agriculture follows a grid traced by extending the ancient Roman roads (Cardo Maximus and the Decumanus Maximus of the ancient cities) into the surrounding agricultural land. Parallel secondary roads were then traced on both sides of the initial axes, dividing the territory into square areas. Residential areas within modern cities present a different structure (Figure 8(d)), where similar patterns are produced by street geometry adapted to exclude traffic at the local street level and facilitate flow at the collector and arterial levels. In such systems, major internal roads run between communities, rather than through them, and they create grid squares where the road network uses cul-de-sac streets complemented by (for example) bike and footpaths that connect the entire sector and beyond.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship and/ or publication of this article: This work has been supported by the University of Padova grant 60A08-5455/15 "the analysis of the topographic signature of anthropogenic processes", by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No 639828), and by the Fondazione Cassa di Risparmio di Padova e Rovigo (CARIPARO) Visiting Professorship at the Department of Land, Environment, Agriculture and Forestry (TESAF) of the University of Padova. ORCID iD Paolo Tarolli https://orcid.org/0000-0003-00435226 Damian Evans https://orcid.org/0000-0003-03204319 Erle C Ellis https://orcid.org/0000-00022006-3362

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.