Answer:
Parent rocks
Step-by-step explanation:
The minerals are the essential elements present in the soil that increases its productivity. The minerals include iron, calcium, potassium, sulfur, magnesium and many more. They are also comprised of humus that is formed from the decayed organisms. These minerals are typically formed from the weathering of the parent rock materials. The parent rocks undergo the physical, chemical and biological type of weathering as a result of which the rocks break down and form these smaller particles, that eventually give rise to the formation of various minerals.
In a soil profile, the parent rocks are present at the bottom and the much finer soil particles comprised of different minerals are present at the top, forming the topsoil and the subsoil in a vertical order.