We live in the Ottawa valley, a lowland traversed by the Ottawa River and its tributaries, and bordered by the rugged terrain of the Canadian Shield. Over geological time, this area has experienced mountain building and erosion, tropical and temperate seas, thick ice sheets, and erosion by rivers. The greater Ottawa-Gatineau area is underlain by soil, sediment, and rock that have been, and still are being, shaped by earth processes, yielding a geological landscape, or geoscape. Understanding how our geoscape works is essential to the wise use of the land.