Lecture, three hours; discussion, one hour. Requisites: Mathematics 33A, Physics 1A, 1B, and 1C (or 1AH, 1BH, and 1CH). Recommended: course 1 or 8. Crust-to-core tour of Earth and physics used to explore it. Isostasy, plate tectonics, mantle convection, and geodynamo as discovered with tools of elasticity, seismology, fluid mechanics, and thermodynamics. P/NP or letter grading.