Earth's core is the most remote part of our planet, recognized as a compositionally distinct region little more than a century ago. It remains the final frontier of our knowledge about Earth. Advances in seismology, computational and experimental mineral physics, geodynamics, geomagnetism, paleomagnetism, and geochemistry have made core research into a truly multidisciplinary effort.

First we must put some boundaries around our topic, to contain it as far as possible in space and time. For space, I consider largely the areas shown in Figures 1.1 and 1.2. Looking at the geological map, we see a central region, running from Cockermouth in the NW to Kendal in the SE, which is divided into three main geological regions. This forms the main area of mountains, the central part of the threefold division being the most mountainous. (The southern section is hilly rather than mountainous.) To the west, there are large masses of pink crystalline rock, near Ennerdale and Wastwater, and somewhat similar rock is found on the eastern side at Shap. Dark crystalline rock is found at the northeastern edge of the mountains at Caldbeck Fell, and also round the northern edge of the hills. There is a 'frame' of sandstones, coals and limestones right round the mountain region.

Earth is a very small part of a vast universe, but it is our home. It provides the resources that support our modern society and the ingredients necessary to maintain life. Knowledge of our physical environment is critical to our well-being and vital to our survival. A basic geology course can help a person gain such an understanding, and can also take advantage of the interest and curiosity many of us have about our planet—its landscapes and the processes that create and alter our physical environment.

The past decades have witnessed a tremendous improvement in our ability to precisely measure deformation of the earth’s crust. Prior to the advent of space-based geodetic systems, crustal strains were measured by triangulation, leveling, and following the advent of lasers, Electronic Distance Meters (EDM). Very Long Baseline Interferometry (VLBI) was the first system to determine relative motion of sites at intercontinental distance scales and thus measure contemporary rates of platemotion.