4. Deep Earth geology

Abstract

The distance from the Earth’s surface to the centre of its core is 6,370 kilometres. Humans have penetrated—with difficulty, and the help of sophisticated technology—to a little more than 4 kilometres below ground; and to a depth of 12 kilometres, probing with boreholes. That does not even get us through the Earth’s crust, so what lies in the gigantic realm of the Earth’s depths? ‘Deep Earth geology’ considers the different areas of study of the Earth’s interior, including petrology—the study of igneous, metamorphic, and sedimentary rocks—and magma studies that provide the tangible evidence of the Earth’s history. It also discusses seismology, geophysics, magnetism, and structural geology.