Complete the following paragraph to describe soil profiles. Soil profiles are vertical sections of the ground that range from the topmost layers to the bottommost unaltered rock below. Within a soil profile, each layer is referred to as a(n) soil horizon. The uppermost layer is typically humus, or decaying organic matter and all living organisms within it. This layer, also called the layer, should have the most ; however, they are often leached away. The second layer contains little or no , but does often contain soluble nutrients that were leached away from upper layers. This layer is referred to as the layer. The bottommost layer is typically that is shattered or weathered and is referred to as the layer. .