by The surface of the earth is the “living skin” of our planet – it connects the physical, chemical and biological systems. Over geologic time, landscapes change as this surface evolves, regulating carbon and nutrient cycling as rivers carry sediment into the oceans.
All of these interactions have far-reaching effects on ecosystems and biodiversity – the many living things that inhabit our planet.
Therefore, reconstructing how Earth’s landscapes evolved over millions of years is a fundamental step in understanding the changing shape of our planet and the interaction of things like climate and tectonics. It can also give us clues about the evolution of biodiversity.
In collaboration with scientists in France (French National Center for Scientific Research, ENS University of Paris, University of Grenoble and University of Lyon), our team at the University of Sydney has now published a detailed geological model of Earth surface changes in the prestigious journal Science.
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Our model is the first dynamical model – a computer simulation – of the last 100 million years with a resolution of up to 10 kilometers (6.2 miles).
In unprecedented detail, it shows how the Earth’s surface has changed over time and how this has affected the way sediments move and settle.
Our model is divided into frames of one million years and is based on a framework that incorporates plate tectonic and climatic forces with surface processes such as earthquakes, weathering, changing fluxes and more.
Three years in the making
The project started about three years ago when we started developing a new global-scale landscape evolution model capable of simulating changes over millions of years.
We’ve also found ways to automatically add other information to our framework, such as paleogeography—the history of Earth’s landscapes.
For this new study, our framework used state-of-the-art plate tectonic reconstructions and simulations of past climates on a global scale.
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Our advanced computer simulations used Australia’s National Computational Infrastructure running on hundreds of computer processors. Each simulation took several days to create a complete picture to reconstruct the last 100 million years of Earth’s surface evolution.
All of this computing power has resulted in global high-resolution maps showing the highs and lows of Earth’s landscapes (elevation) and the fluxes of water and sediment.
All of this fits well with existing geological observations. For example, we combined data from contemporary river sediments and water flows, catchment areas, seismic surveys, and long-term local and global erosion trends.
Our main results are available as time-based global maps at five million year intervals from the Open Science Framework.
Water and sediment flow through space and time
One of the fundamental surface processes on Earth is erosion, a slow process by which materials such as soil and rock are worn away and carried away by wind or water. This leads to sediment flows.
Erosion plays an important role in the Earth’s carbon cycle – the endless global circulation of one of the essential building blocks of life, carbon.
Studying the ways in which sedimentary flows have changed through space and time is crucial to our understanding of how Earth’s climate has changed in the past.
We found that our model reproduces the key elements of Earth’s sediment transport, from the catchment dynamics that represent river networks over time to the slow changes of large-scale sedimentary basins.
From our results, we also found several inconsistencies between existing observations of rock strata (strata) and predictions of such strata. This shows that our model could be useful for testing and refining reconstructions of past landscapes.
Our simulated landscapes of the past are fully integrated with the various processes, particularly the hydrological system – the movement of water – and offer a more robust and detailed view of the Earth’s surface.
Our study reveals more details about the role that the ever-evolving Earth’s surface has played in moving sediments from mountain peaks to sea basins, ultimately regulating Earth’s carbon cycle and climate variability through deep time.
By examining these results along with the geological record, we will be able to answer long-standing questions about various crucial features of the Earth system – including how our planet recycles nutrients and gave rise to life as we know it has.
Tristan Salles, Lecturer, University of Sydney
This article was republished by The Conversation under a Creative Commons license. Read the original article.
