Practical Geology

Reading rock samples like the pages of a book, Professor Cotter recounts the stories they tell of change across vast stretches of time. He presents three key concepts that will open your mind to the fun and fascination of practical geology. Then he focuses on the idea of deep time, noting that humans have been around for only an infinitesimal fraction of Earth’s 4.6-billion-year geologic drama.

Geomorphology is the study of landscapes and their individual landforms. Learn the five major influences on landscape formation. Use this background to tour the United States, which is a remarkable laboratory of geomorphology with features such as the Appalachian and Rocky Mountains, the Grand Canyon and Channeled Scablands, and more.

Go outside and find an outcrop—a roadcut, cliff face, or other site where rocks are exposed. These are ideal places for practicing field geology. Professor Cotter gives tips on safety, maps, tools, and techniques. A notebook and record-keeping are essential. Amateur geologists can make important discoveries, so field geology is your chance to advance knowledge while enjoying the outdoors.

Rivers are the key to understanding why many landscapes look the way they do. Study how rivers form, how they sculpt the land, how water and sediment move in a river, and how rivers change course over time. Rivers also create habitats for plants and animals, both of which influence the landscape. Finally, signs of vanished rivers tell the story of geologic events in the deep past.

Visit the beach with a geologist’s eyes and see how the interaction of waves, ocean currents, and winds lead to the ebb and flow of sediments and blending of landforms. Consider the four types of waves and what they reveal about the ocean floor just offshore. Also, zero in on individual grains of sand, identifying their minerals and tracing their origin. Reflect on why beaches are sandy at all.

Sedimentary rocks make up a substantial majority of rocks at Earth’s surface. In this episode, focus on clastic rocks, which are composed of broken fragments of pre-existing rocks. The fragments can vary in size from clay particles to silt, sand, gravel, and larger pieces. Learn how these rocks form and the rich stories they tell about the past.