1. What is geology?

Geology is a little like having the world’s biggest and best time machine at one’s disposal. The field of enquiry is the whole Earth, its 4.54-billion-year history, and everything that has formed on our planet over that time. ‘What is geology?’ explains that the geological record is a record of ancient worlds, of dynamic and evolving landscapes and submarine-scapes. Geology is a science encompassing virtually all the other sciences—chemistry, physics, biology, geography, oceanography, and many others—and involves or impinges upon many of the humanities and arts, and day-to-day life. It involves looking deep into the Earth’s structure, but also extends to the observation of other planets and moons.

7. Geology for resources

Humans have been practical geologists since even before our own species, Homo sapiens, walked the Earth. The exploitation of rock-bound resources required a level of understanding of rock composition and structure that remains impressive today. The mining of metals, the extraction of building stone, the engineering of waterways, developed over the centuries. Today, geological materials have become utterly pervasive within our lives. ‘Geology for resources’ considers how geologists seek out these resources from within the crust of our planet, focusing on fossilized hydrocarbons used as energy resources (coal, oil, and gas); the metal extraction process from metal ores; industrial mineralogy; phosphates, essential nutrients in agriculture; and hydrogeology, the study of underground water resources.

6. Geological fieldwork

The rare, exotic, and wonderful has been one of the great attractions of geology, often being the ‘hook’ that initially attracted the attention of many a geological enthusiast. Dating back to at least Greek and Roman times, explorers went in search of mammoth and dinosaur bones, and prospectors targeted precious gems and metal ores. ‘Geological fieldwork’ explains, though, that systematically working out the total geology of a landscape requires a very different approach. It outlines the work of William Smith, who from the late 18th century produced the first geological maps of Great Britain, and describes some of the new technology used in modern geological fieldwork.

9. A very brief history of the Earth

Our planet is ancient—at 4.6 billion years—and over that time it has changed enormously. ‘A very brief history of the Earth’ describes how the Earth and Moon were created in the Chaotian Eon from the collision of two planets: Tellus and Theia. It outlines the heavy meteorite bombardment of the Hadean Eon; the Archean Eon (c.3.8 billion years ago) when rocks were first preserved; the arrival of oxygen in Earth’s atmosphere and explosion of organic life in the Proterozoic Eon; and the Phanerozoic Eon, in which we still live. The various eras of this eon are described: the Palaeozoic Era, the Mesozoic Era, and the Cenozoic Era.

2. Geology: the early days

‘Geology: the early days’ provides a brief history of ideas on the Earth and its processes. Among the earliest recorded scientific speculations on the Earth were those of the ancient Greeks, such as Anaximander of Miletus and Pythagoras. Other cultures that independently developed ideas include the Vedic Period of India (c.1300–300 bc) and the Song Dynasty of China (960–1279 ad). Huge strides were made during the Enlightenment period, and the key contributions of figures such as Georges-Louis Leclerc, Comte de Buffon, James Hutton, Baron Georges Cuvier, Mary Anning, William Buckland, Charles Lyell, Abraham Gottlob Werner, and Adam Sedgwick are discussed, with the creation of the Geological Time Scale.

8. Geology for society and the environment

Geology is involved, somehow or another, in most of the resources that sustain us. Equally, it is a significant factor in many of the hazards that threaten us, and geology is often involved in devising means of avoiding, or counteracting, or simply of living with, these hazards as sensibly as possible. ‘Geology for society and the environment’ considers both Earth-generated hazards, such as volcanoes, earthquakes, and tsunamis, and human-made geological hazards, including the rise in carbon release fuelling climate change and the ever-increasing volume of waste materials and pollutants. It looks at how geology is used to help devise the best means for society to deal with these hazards.

5. Earth surface geology

‘Earth surface geology’ considers the particular conditions created by the water cycle governing the distinctive surface geology of Earth. It looks at the efficiency of the rock cycle: the breakdown of ‘primary’ igneous rocks into sediments, which are buried and lithified to produce sedimentary rock, which in turn becomes metamorphosed as heat and pressure increase, finally ending in melting and magma production. It also looks at the ways that geological time has been subdivided using biostratigraphy (the tracking of species’ evolution through fossils) and tracing chemical changes in the rocks. Earth’s evolution has included regular and gradual influences, with episodes of sudden massive change from more or less random events.

3. Modern breakthroughs and revolutions

The early geologists built a detailed relative history of the Earth, much of which holds true today, but they had no idea of how long that history was in years. ‘Modern breakthroughs and revolutions’ explains that the ability to measure Earth time transformed geology. With the discovery of radioactivity in 1896, radiometric dating of rocks became a possibility. This numerical dating, when combined with the relative dating provided by fossils, provided a means to calibrate the long and eventful history of our planet. The study of ocean floor geology and the birth of the revolutionary plate tectonics concept explained the patterns of mountain ranges, volcanism, and earthquakes.

4. Deep Earth geology

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.