For over a century, the Geophysical Laboratory of the Carnegie Institution of Washington has witnessed exciting discoveries and ingenious research, made possible by the scientific freedom granted to members of the department. For the most part, this research has involved laboratory experimentation on the physics and chemistry of rock-forming minerals at high temperature and pressure. This third volume in a series of five histories of the Carnegie Institution documents the contribution made by the members of the Geophysical Laboratory to our understanding of the Earth, from mineral formation deep below the surface, to the search for the origins of life, and out into space to study the chemical evolution of the interstellar medium. Field work has taken researchers from active volcanoes to ships collecting ocean sediments, and geological mapping expeditions around the world. Contemporary photographs throughout illustrate the evolution of the department and its research.