The first high-resolution model of the evolution of the earth’s surface

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Climate, plate tectonics, and various surface processes, especially the transport and accumulation of sediment from land to the oceans, continue to shape the Earth over time. University of Sydney researchers, in collaboration with French researchers, are now offering a highly detailed geological model of how our planet’s surface has evolved over the past 100 million years. This new model could help predict how the Earth will change in the face of climate change.

Geomorphology is the discipline that studies the relief of land and all the processes that form it. Understanding how landscapes have evolved in the past and the various factors that come into play can help predict future changes. “To predict the future, we need to understand the past. But our geological models have provided only a partial picture of how the recent physical features of our planet were formed,” says Dr. Tristan Salles, a researcher at the University of Sydney School of Geosciences and the first author of the study.

He and his collaborators are presenting to Science the results of a high-resolution surface physiography model that provides insights into how today’s geophysical landscapes were created and how millions of tons of sediment entered the oceans over the past 100 million years. This is the first high resolution global computer simulation of the continuous interaction between river basins, erosion and sedimentation. For Dr. Salles, this is an important step forward in helping scientists understand and predict the future.


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Towards a Better Understanding of the Marine Environment

The processes that formed the earth’s surface in time are “recorded” in nature in different ways. Geological scientists are particularly interested in sediments because their contributions are closely related to environmental factors; precipitation or snowfall, for example, affects the formation of sediments by erosion and their movement across the landscape. Tectonics also play an important role, creating more or less deposits depending on the direction of uplift.

Erosion also plays an important role in the Earth’s carbon cycle. Thus, it is important to fully understand all of these processes and their contribution to surface physiography, because in addition to changing landscapes, they also have a significant impact on ecosystems and biodiversity, notes Dr. Halls in The Conversation. How sediment flows have changed over time can help us understand how Earth’s climate has changed in the past.

Using a framework that combines tectonic and climatic forces with surface processes (earthquakes, weathering, river evolution, etc.), the team developed a new dynamic model showing the evolution of the earth’s surface over the past 100 million years at high resolution (up to ten kilometers!), sliced ​​into frames in one million years. The following animation shows the “hot spots” of sediment transport and deposition.

This unprecedented high resolution model gives geologists a more complete view of geodynamics. It highlights sediment transport dynamics that scientists have not been able to understand before and that may help improve our understanding of modern ocean chemistry. “Because ocean chemistry is rapidly changing due to anthropogenic climate change, a more complete picture could help our understanding of the marine environment,” said Dr. Salles.

Predict the evolution of the earth’s surface

This model is the result of almost three years of research. The team started by developing a new model of landscape evolution on a global scale, capable of simulating changes over millions of years. Then they managed to gradually integrate other information into this model. For their new study, they used state-of-the-art tectonic reconstructions and past climate modeling. The global maps generated by the model, which show heights as well as water and sediment flows, are in good agreement with geological observations.

Maps of the 100 highest river sediment flows 50 and 25 million years ago. © Tristan Salles

This model sheds light on how terrestrial sediment transport has regulated the planet’s carbon cycle and thus climate fluctuations over millions of years. But the simulation results also revealed some inconsistencies between existing observations of rock layers (layers) and predictions. “This shows that our model can be useful for testing and refining landscape reconstructions of the past,” says Dr. Salles.

Scientists now have a dynamic and detailed context to test various hypotheses about how the Earth’s surface will respond to future climate changes and tectonic forces.

But that’s not all ! This new geological model may also shed light on the origin of life on Earth. “By examining these findings, along with geological data, we can answer long-standing questions about various critical features of the Earth system, including how our planet recycles nutrients and gives rise to life as we know it,” the expert concludes. .

T. Salles et al., Science.

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