Earth’s Interior

Earth’s Interior 

1. How does Earth’s interior work, and how does it affect the surface? 

As planets age and cool off, their internal and surface processes gradually change. Manifestations of changes within Earth’s interior—such as the development of mountains and volcanoes—have a huge influence on the nature of Earth’s surface and atmosphere. Scientists know that much of the rock in the Earth’s mantle (the thick layer between the core and crust), which is under extreme pressure and very high temperature, behaves like a viscous liquid. This vast interior, however, is largely inaccessible to direct study. For over a century, seismic wave, geomagnetic, and gravity measurements made at the surface have been improving understanding of Earth’s internal structure. Despite continuing advances, however, scientists are only beginning to explore the connections between Earth’s core, magnetic field, mantle, and surface and to investigate why Earth differs from other planets, or how it may change in the future.

2. Why does Earth have plate tectonics and continents? 

 A major focus of Earth science has been on deciphering the nature of the continents—the features that make Earth habitable for land-dwelling life. How and when did the continents form? How have they changed? Why do the Atlantic coastlines of South America and Africa look like pieces of a puzzle? Plate tectonics—the description of Earth’s outermost layers in terms of a small number of large rigid plates in relative motion—has offered many breakthrough insights since it became a central paradigm for geology nearly 40 years ago. The motion of tectonic plates and interactions at their boundaries are now known to be a driving force behind earthquakes, volcanic eruptions, the formation of mountains, and the slow drift of continents over Earth’s surface. Although plate tectonic theory explains many of Earth’s surface features, it is not known why Earth has plates or what the relationships are between plate tectonics and Earth’s abundant water, continents, and the existence of life. Answering such questions will require improved models, studies of modern plate boundaries, and comparisons with other planets. 

3. How are Earth processes controlled by material properties?

 It’s the little things that make all the difference. Scientists now recognize that large-scale processes on Earth, such as plate tectonics, are driven by the nature of the materials that make up the planet—down to the smallest details of their atomic structures. The high pressures and temperatures of Earth’s interior, the enormous size of the planet and its structures, the long expanse of geological time, and the vast diversity of materials present challenges to studying Earth materials. Breakthroughs in this area are now at hand, however; new analytical tools and advanced computing capabilities are improving the study and simulation of Earth materials at the atomic level and promise to improve predictions of how these material properties will affect planetary processes.