This manual is about structures that occur within the Earth’s crust. Structures are the features that allow geologists to figure out how parts of the Earth have changed position, orientation, size and shape over time. This work requires careful observation and measurements of features at the surface of the Earth, and deductions about what’s below the surface. The practical skills you will learn in this course form the foundation for much of what is known about the history of the Earth, and are important tools for exploring the subsurface. They are essential for Earth scientists of all kinds.