The earth’s surface is the “living skin” of our planet—it connects physical, chemical, and biological systems. Over time, landscapes change as this surface develops, controlling the carbon cycle and nutrient circulation as rivers carry sediment to the oceans.
All of these interactions have far-reaching effects on ecosystems and biodiversity—the many living things that inhabit our planet.
As such, reconstructing how Earth’s landscapes evolved over millions of years is a key step toward understanding the changing shape of our planet, and the interaction of things like climate and tectonics. It can also give us clues to the evolution of biodiversity.
Working with scientists in France (French National Center for Scientific Research, ENS Paris university, University of Grenoble, and University of Lyon), our team at the University of Sydney has now published a detailed geological model of Earth’s surface changes in prestigious journal Science.
Ours is the first dynamic model—a computer simulation—of the last 100 million years at a high resolution of up to ten kilometers. In unprecedented detail, it shows how the Earth’s surface has changed over time, and how this has affected the way sediment moves and settles.
Broken down into one-million-year frames, our model is based on a framework that integrates plate tectonics and climatic forces with surface processes such as earthquakes, climate change, changing rivers, and more yet.
Three Years in the Making
The project started about three years ago when we started building a new one global-scale model of landscape evolution, capable of simulating millions of years of change. We 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 an innovative method plate tectonic reconstructions and simulation of past climates on a global scale.
Our advanced computer simulations used Australia National Computational Infrastructure, running on hundreds of computer processors. Each simulation lasted several days, building a complete picture to reconstruct the past 100 million years of evolution on Earth’s surface.
All this computing power has resulted in global high-resolution maps that show the heights and lows of Earth’s landscapes (elevation), as well as water and sediment flows.
All of this fits well with existing geological observations. For example, we combined data from the present river sediment and water flowdrainage basin areas, seismic surveys, and long-term local and global erosion trends.
Our primary outputs are available as time-based global maps at five million year intervals from the Open Science Framework.
Water and Sediment Flux Through Space and Time
One of the main processes on Earth’s surface is erosion, a slow process in which materials such as soil and rock are broken down and carried away by wind or water. This results in sediment flows.
Erosion plays an important role on Earth carbon cycle—the endless global circulation of one of life’s essential building blocks, carbon. Investigating the way sediment flow has changed in space and time is important for our understanding of how Earth’s climates have varied in the past.
We find that our model reproduces key elements of Earth’s sediment transport, from catchment dynamics that describe river networks over time to slow changes of large sedimentary basins.
From our results, we also found some inconsistencies between existing observations of rock layers (strata), and predictions of such layers. This shows that our model can be useful for testing and refining reconstructions of past landscapes.
Our simulated past landscapes are fully integrated with the various processes at play, especially the hydrological system—the movement of water—providing a more robust and detailed view of the Earth’s surface.
Our study sheds more detail on the role played by Earth’s ever-evolving surface in the movement of sediments from mountain peaks to ocean basins, ultimately controlling the carbon cycle and the Earth’s climate changes in deep time.
As we explore these results alongside the geological record, we can answer long-standing questions about various important features of the Earth system—including how our planet cycles nutrients, and gave rise to life as we know.
This article was republished from The conversation under a Creative Commons license. Read the original article.
Photo Credit: Sander Lenaerts in Unsplash