Landscapes of extinction and evolution: Earth surface processes in the late Palaeozoic

The role of life in the long-term shaping of the planetary surface needs to be understood to ascertain whether Earth is singular among known rocky planets, and to frame predictions of future changes to the biosphere: the sedimentary rock record is a valuable archive that reveals how Earth surface processes evolved in line with organisms, and the turbulent interval of the late Palaeozoic is an ideal case study to interrogate this question.

Sedimentary and geomorphic processes occur in the same theatre as the majority of life on Earth, and biological shaping of physical processes and form is important at the present day. Different organisms aggregate or disaggregate sediment; erode, mix, bind, or stabilize sediment piles; and can induce turbulence in, concentrate, or dampen the movement of fluids that transport sediment. Through physical-biological feedback, these processes shape the Earth as we know it today, determinign sediment type and the morphology of landforms such as dunes and river channels. If we are to fully understand how significant these processes are, we need focussed investigation of geological intervals when they first came into play. The late Palaeozoic is a perfect interval to study how these processes have created the landscapes of planet Earth. The interval post-dates the evolution of many agents of terrestrial landscape engineering (e.g., trees, burrowing organisms), but was affected by major upheavals in the Earth system: equatorial aridification and the collapse of the rainforests at the end of the Carboniferous, a major ice age, and the biggest mass extinction in Earth history.

Ancient landscape evolution is archived in the sedimentary record, as individual successions host facies and lithological attributes that identify past environments. A holistic view of these environments, from a 90 Ma interval of major turbulence in the Earth system, will demonstrate the feedback on landscapes and sedimentation that are imparted when different groups of organisms are stressed or advantaged by global changes. The project will focus on the interval of the late Carboniferous (c. 310 Ma) through to the mid Triassic (c. 290 Ma). This interval witnessed major episodes of extinction and habitat destruction (e.g., Kasimovian rainforest collapse; the P-T mass extinction), and climate change (e.g., LP ice age; Permian desertification in Euramerica; the Carnian pluvial episode). The project will evaluate how landscapes and sedimentation responded and recorded these system shifts

The student will follow a series of work packages that have previously been shown to be successful in assessing global changes related to life evolution (namely, the impact of land plant evolution on fluvial form, and the consequences of the invasion of the land by animals). The project will identify a suite of suitable case studies, from the UK and worldwide, where detailed sedimentary geological models will be constructed from original field data, to ascertain landscapes in similar tectonic and climatic settings, from intervals before and after major events. This will be coupled with the construction of a major database, which will identify secular characteristics of non-marine facies from delineated intervals within the late Palaeozoic. This combined approach of detailed sedimentary geology fieldwork case studies, and an atlas of evolving seidment character through time, will firmly address how the Earth's landscapes responded to what was one of the most turbulent periods of the planet's pre-modern history.