A biostratigraphical signature for the Anthropocene
The base of the Cambrian System is recognized by a characteristic (marine) trace fossil suite assigned to the Treptichnus pedum Biozone, which signals increasing complexity of animal behaviour and demarcates the Cambrian from the (older) Ediacaran System (Proterozoic Eonathem). Ichnotaxa of the T. pedum Biozone are not the earliest trace fossils, and are preceded in the latest Proterozoic by a progressive increase in the diversity of trace-producing organisms and the communities they comprised, the structural and behavioural complexity of the trace fossils, and even the depth of burrowing in sediments. Parallels can be drawn with the increasing complexity of subsurface structures associated with human cities, which also reflect evolution of an increasingly complex community. Before the nineteenth century, these structures were limited and simple, but beginning with the development of London in the mid-nineteenth century as the world’s first megacity, subsurface structures have become increasingly complex, reflecting the technology-driven behaviour of twentieth- and twenty-first-century humans.
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A Stratigraphical Basis for the Anthropocene
Humankind has pervasively influenced the Earth’s atmosphere, biosphere, geosphere, hydrosphere and cryosphere, arguably to the point of fashioning a new geological epoch, the Anthropocene. To constrain the Anthropocene as a potential formal unit within the Geological Time Scale, a spectrum of indicators of anthropogenically-induced environmental change is considered, and shown as stratigraphical signals that may be used to characterize an Anthropocene unit, and to recognize its base. This volume describes a range of evidence that may help to define this potential new time unit and details key signatures that could be used in its definition. These signatures include lithostratigraphical (novel deposits, minerals and mineral magnetism), biostratigraphical (macro- and micro-palaeontological successions and human-induced trace fossils) and chemostratigraphical (organic, inorganic and radiogenic signatures in deposits, speleothems and ice and volcanic eruptions). We include, finally, the suggestion that humans have created a further sphere, the technosphere, that drives global change.