What is the term for the bottom material in which soil horizons form?

The bottom material in which soil horizons form is referred to as parent material. It serves as the foundational layer from which soil develops over time through the processes of weathering and organic activity. Parent material can consist of weathered rock or sediment and influences the characteristics of the soil, such as its mineral content, texture, and nutrient availability. Through time, as organic matter accumulates and biological activity occurs, the soil horizons develop, but they are fundamentally based on the properties of the parent material beneath them. Understanding this concept is crucial for grasping soil formation processes and the overall soil profile.